2011 FORMULA ONE GUIDE By Pat Symonds Who’s innovative, who’s conservative: technical analysis of this year’s contenders
Driving Technology Into Pole Position March 2011 Issue No. 125 UK £4.95 USA $9.99
I N T E R N A T I O N A L
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F1’s launch trickery How teams bluff rivals with their new designs
INNOVATE OR FADE AWAY, WARNS FORMER GOVERNMENT MINISTER
HOW TO DESIGN A RACE ENGINE PART 4 DESIGNING THE BRAKE SYSTEM
THE RACECAR THAT LURED FOR OUR 750FORMULA BUILD LOTUS BACK TO LE MANS SPECIAL REPORT ON BRAKE TECHNOLOGY COVERS 125 v4b.indd 1
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March 2011 CONTENTS Issue 125
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COVER STORY - Page 16 Legend has it that when teams used to test at Mugello, thermal imaging devices were hidden in the vans of the hot-dog vendors”
F1 2011
Pat Symonds guides us through 2011’s F1 contenders, plus lifts the lid on the subterfuge used by teams to trick rivals INDUSTRY NEWS
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“Time to rethink the approach to rulemaking,” urges F1 and Le Mans designer; privateer takes up Le Mans hybrid challenge; McLaren to supply NASCAR’s fuel injection; Opel contemplates DTM comeback
Volume 18 Issue 5
THE CAR THAT LURED LOTUS BACK TO LE MANS
Published March 2011 The next issue will be published
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in early April 2011
We chart the development of a GT racer that puts Lotus on a collision course with endurance racing’s most successful manufacturers
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Lord Paul Drayson, former UK government minister and now a Le Mans team owner and successful entrepreneur, set the theme for Race Tech’s World Motorsport Symposium: how will motorsport embrace its future?
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ENGINE TECHNOLOGY
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Former F1 engine designer John Lievesley uses camshaft positioning to illustrate a technique he favours, plus proposes an experiment that could well damage your marriage!
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John Coxon concludes his guide to oil systems by considering the intricacies of dry sump technology
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SPECIAL REPORT 58
8,9,10,11,13,14,15,16,17,18,19,20,21,22,23,
We report on a number of companies that have ripped up their own rulebook to continue the motorsport brake industry’s pursuit of excellence
24,25,26,27,28,29,30,31,32,33,35,36,37,38,
PRACTICAL RACER
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Graham Templeman and Rod Hill set to work designing the brake system for their 750Formula racecar
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RACE EQUIPMENT DIGEST
99,100,101,102,103,104,105,106,107,108,109, 110,111,112,113,114,115,116,117,118,119,
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A look at the latest products launched in the motorsport sector
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INTRODUCTION ISSUE 125
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EDITOR William Kimberley
ASSISTANT EDITOR Chris Pickering
FUEL RATIONING ON THE HORIZON?
CONTRIBUTING EDITORS Pat Symonds John Coxon Steve Bridges Graham Templeman Matt Youson
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T IS coming up to 40 years ago that the Arab-Israeli war of 1973 led to fuel rationing and a restriction on its use. I remember being issued with coupons that were actually printed for the petrol rationing in World War Two while some countries adopted a policy of even-odd in which drivers could only go into a filling station on even days if their car’s licence plate was an even number or on odd days if the licence plate was an odd number. Torrid at the time, fortunately things came back to normal after a relatively short time.
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Unfortunately, though, fuel rationing is coming back on the agenda. However, rather than as a stopgap to get through a particular crisis, it is being seen as a long-term policy goal. A report by a panel of lawmakers that was recently published in the UK has suggested that the country may be heading for fuel rationing in the next 10 years. This is not simply due to oil running out but a question of the country being able to meet its carbon emission targets by 2050. The idea is that every adult is given an equal free entitlement of tradeable energy quotas (TEQ) every week but which can be traded at a single national price that would rise and fall in line with demand. Along with financial payments, they would be used to purchase any form of energy, all fuels and electricity carrying a “carbon rating” in units, each one representing one kilogram of carbon dioxide – or the equivalent in other greenhouse gases – released in the fuel’s production and use.
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that runs through society at large. The fall of a dictator here and there, catastrophic natural disasters and terrorist outrages will never go away, but the underlying fears about global warming and that oil is going to run out are going to grow and grow – and the motorsport industry needs to be seen to reflect that. For quite some time now, the UK government has had in place a taxation system for cars whereby the higher the CO2 emissions, the more annual tax is paid on that vehicle. In so doing, it has manipulated consumers’ demands which the car companies have responded to by producing vehicles that are more attractive from a taxation point of view. Sergio Rinland, the highly respected and senior motorsport engineer who has been round the block a few times, has suggested the sport’s governing bodies should adopt a similar strategy as you will read in the main news story. Instead of directing engineers on how they should build their cars and engines, he argues that the outcome should be specified, in other words, the engine’s output and the car’s downforce at a particular speed and he goes into the mechanics of how this is achievable. This, he says, will clear the way for engineers to innovate and come up with solutions that might be more useful to the world at large. It might even lead to a diverse grid of cars rather than the clones that we tend to have nowadays.
So what you might say. Is it not just a political wish list and that such a scheme will be impossible to implement?
At the moment, we take it as a fundamental right that fuel is freely available but we cannot assume that it is going to last. Motorsport needs to be seen as an active contributor to finding alternative solutions before it too finds itself rationed out of existence.
Whether that is the case or not, there is no doubt that the use of energy in whatever form is going to continue to be the underlying concern
William Kimberley EDITOR
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XFORD, UK: “It’s time to rethink the rulebook.” These were the words of Sergio Rinland, a man who has engineered Formula One and Le Mans cars for more than three decades, in his presentation at the Race Tech World Motorsport Symposium in Oxford. His challenge for the governing bodies was to be proactive and not reactive in their rule-making. “What I am proposing are proactive regulations, what pilots call being ahead of the power curve,” said Rinland. “If you think about it, the rulemakers are always following the lead of the motorsport engineers by restricting them in whatever way possible,” he said. “When it comes to aerodynamics, they have tried to limit downforce but time and again they have been outsmarted by the designers in a short
ABOVE “time to rethink the rulebook”
TIME TO RETHINK THE APPROACH TO RULEMAKING By William Kimberley
time. This is because they are always reactive, looking at historic data, things that have happened in the past and reacting to them rather than predicting what might happen in the future. Twenty years ago it would take the teams two to three years to catch up with the regulations as the technology wasn’t available. Now, though, with the amount of CFD and wind tunnel time that the teams are using, they are able to catch up in six months which means that the rulemakers are then back to square one. Furthermore, this can only get worse from their point of view to the point where the teams will be able to react instantly to any regulation changes and outsmart the regulators even faster. “So there needs to be a different approach to regulations and regulation changes. In my view rather than go through the cat and mouse scenario of rulemaker versus team, why not just regulate the downforce of a car at a specified speed? “With all the tools that we have today, it
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would be simple to tune these regulations and even kill any flexible components on the car because it is possible that stress analysis and vehicle dynamics can be done at the same time as CFD. It means that every element of the car can be controlled but having said that, all that would be regulated is the outcome.” Rinland also said that the same philosophy can also be applied to the engine by using a torque sensor on the driveshaft and an energy consumption restriction. “It would mean that the engine configuration could then be opened up,” he said. “Inline four or V10, blown or unblown, diesel or ethanol, hybrid or even electric – the only criteria would be the specified power output and the energy to be consumed and if that was exceeded during a race meeting, then the team using it would face draconian punishment such as being put on a four-race ban. “It’s the same thing in aerodynamics. The downforce would be regulated to limit the cornering speed which is the danger zone
but drag being left untouched as that is deemed to be efficient, so the teams would be allowed to be creative in this area. “My concept is that the governing body would build a virtual car that’s run on a simulator until the desired lap time is reached with the required amount of downforce and power; that information then being passed onto the teams. So they know the amount of downforce they are allowed but the rest, especially drag, is free. If it’s reduced, then we are doing something that’s relevant. It will lead to people fighting for efficiency and being innovative, resulting in different answers and therefore different cars. If it was found that they were coming too fast for any track the following year, then the simple answer would be to reduce the power. The end result is a virtuous circle of efficiency with the car running at the same speed but with less power and less energy consumption. “At the moment, everything is in the wrong direction because teams are getting more and more downforce which
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is irrelevant to today’s road car and society in general. “The process as I see it would be that an open source CFD code would be used by the governing body as it wouldn’t be fair to impose on teams an expensive proprietary program that could cost thousands of euros or pounds to buy the software just to comply with the regulations. In my view it would be like giving the teams a ruler with which they have to measure their car, sending back the results and the design to the governing body. It could be argued that the teams could supply the data from their wind tunnel testing, but as is well known, different wind tunnels compute different data which is why I think the open source CFD is the most economical and viable answer.” When presented at scrutineering, the car would be scanned, as is currently done in NASCAR, and the surfaces compared to the one the governing body has on file from the team at the start of the season. If necessary, it could then be run by the governing body to ensure the values were being adhered to. The goals that could be set if standard metrics were created would be a full integration of an aero map with dynamic analysis, yaw values and the definition of wake so that the car did not reduce the following car’s downforce by a certain value at a certain
distance. Data from aero tests could also be included that showed the car had passed nose up, side and backwards tests to reduce the risk of flipping over. In Rinland’s view, his proposal would see a greater variety of different shapes of car on the grid powered by different engines. “If you look at the current crop of Formula One cars, it’s very hard to say anything meaningful as they are all virtually the same except for a few detail differences. Furthermore, if a team comes up with a good idea, such as the double diffuser or Fduct last year or possibly the exhaust layout as seen on the Lotus Renault this year, every car on the grid will have one just a few weeks later as everyone is working to the same tightly defined
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regulations and have exactly the same problems, hence the solutions convergence. However, if you have fundamentally different cars then if a team does come up with a clever solution, it cannot necessarily be copied by the others if they are running a completely different shape. “It would allow aerodynamicists and engineers to use their imagination and come up with different solutions, some of which will work and some won’t.” RT
ABOVE If teams just had to meet downforce figures and nothing else, then radical designs like Adrian Newey's X1 racer might even make the grid
Vehicle Dynamics and Control seminar CAMBRIDGE, UK: A one-day seminar to explore recent developments in the design and analysis of vehicle dynamic behaviour will be held at Fitzwilliam College, Cambridge University on Tuesday 5 April. Fourteen presentations in three sessions will cover driver behaviour and modelling, dynamics of low-carbon vehicles, and chassis dynamics and control. Each session will be followed by a panel and audience discussion, so that
issues raised in the presentations can be developed further. Topics include the identification of linear and nonlinear driver steering control by Dr David Cole, Dr Andrew Odhams and Dr Steve Keen (University of Cambridge), car handling qualities and driver modelling by Prof Robin Sharp (Surrey University), rally car driver behaviour by Damian Harty (Prodrive), expert driving techniques at the limit of
handling by Dr Efstathios Velenis (Brunel University) and the role of the tyre in traction-induced driveline vibrations by Matthew Bartram and Dr George Mavros (Loughborough University). For enquiries about the technical programme please contact Dr David Cole, djc13@cam.ac.uk. For enquiries about registration, travel and accommodation please contact Rebecca Loving, RL413@cam.ac.uk. RT
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MOTORSPORTS PROFESSIONAL BELOW The Oreca 01-AIM, on which the hybrid is based, finished top gasoline car in fourth position at last years Le Mans (Photo: Michel Legeay/ACO/Nikon)
HYBRID CHALLENGE AT LE MANS By Chris Pickering
FRIBOURG, Switzerland: It has been confirmed that at least one hybrid car will take part in this year’s Le Mans 24 Hour race. The Oreca 01 Hybrid of Hope PoleVision Racing will be the first hybrid vehicle to contest the French classic since the Panoz Q9 of 1998, and the first entry ever to use an all-mechanical energy storage system. At the time of going to press no other manufacturer had announced the intention to run a hybrid powertrain. Peugeot Sport – previously thought to be the most likely contender to do so – openly stated that it would not be running a hybrid car in 2011 during the launch of the new 908 last month. “After what happened at Le Mans last year the board said, ‘you must make sure you win; you have to focus on one thing’,” said Peugeot Sport boss Olivier Quesnel. “We were not sure that a hybrid would be any more competitive, so it would have been extra complication for nothing.” LMP1 rival Audi has stated that its new
position to run just behind the works teams, to stand out and catch the eye of a manufacturer for 2012. With the resources
R18 will feature ‘progressive electrification’ over the course of its lifespan, but it is not thought to be running a hybrid system this year. Similarly, while Aston Martin has yet to confirm the exact specification of its petrol-fuelled powertrain, the company has yet to say anything which suggests a hybrid is on the cards. Furthermore, there is no sign of the Porsche 911 GT3 R Hybrid that ran at the Nürburgring 24 Hours and Petit Le Mans last year, making the Oreca the only confirmed hybrid in any class. “It’s a huge challenge that awaits us as we’ll be the first private team to race an LM P1 hybrid,” commented Benoît Morand, a co-owner of Hope PoleVision Racing. “Our main aim is reliability, which is of prime importance. We want to be in a
INTERNATIONAL BUSINESS DAYS AT LE MANS LE MANS, France: The 2-day International Business Days event will once again be held in the week of the Le Mans 24 Hour race at the Institut du Mans just outside the track. The first day comprises a visit to the paddock area where delegates can have a chance to meet specified teams while the following day, Thursday, 9th June, is devoted to the “hot dating” system where participants can meet the buyers from different teams. To date, those who have
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confirmed their attendance include Peugeot Sport, Citroën Racing, Oreca, Bosch braking systems, EMC, the Everest Team and Altafran. Being in France, there are also some culinary delights including a gourmet evening at the Auberge de Mulsanne on the evening of the 8th. For more information about packages, exhibiting and sponsorship, go to www.ibdlemans.fr
of a factory squad we’d hope to be able to take the fight to the front-runners.” The car uses the same basic chassis as the Oreca 01, which was the highest placed non-diesel finisher in last year’s event. In place of the original Judd V10 sits a new production-based 2-litre turbocharged four cylinder engine developed for the team by Lehmann Motoren-Technik and due to be marketed under the Swiss Hytech banner. It is combined with a Flybrid System’s mechanical storage system, similar to that originally developed for the Honda Formula One team, which transmits power directly to and from the car’s Xtrac gearbox. Oreca is engineering a series of modifications to the rear end of the 01’s chassis in order to accommodate the hybrid system – a task which is said to be made easier by the four cylinder engine’s compact dimensions. “It’s a great challenge and we’re proud to be part of it,” commented Oreca’s technical director David Floury. “The development of the hybrid system is moving along in parallel to the work on the car itself, so what we’re doing is very new. And I think it’s very interesting to see a private team taking on such a significant project. It shows how good the hybrid regulations are, because they’re opening up new possibilities to the teams … It’s a bit like what we’re seeing on road cars these days with smaller companies coming up with new concepts. I think we’re entering a very interesting period at Le Mans.” RT
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SHOVING AND SPEED PUSHES NASCAR INTO CHANGES By Andrew Charman
RIGHT By a nose: a pair of two-car drafts fought right to the line of the first NASCAR race of 2011, the Budweiser Shootout at Daytona on Saturday 12th February. Kurt Busch in the No 22 Dodge was awarded the win after Denny Hamlin’s no 11 Toyota was judged to have overtaken under the yellow inside track line. (Photo by Nick Laham/Getty Images for NASCAR) DAYTONA, FL: A new track surface and aerodynamic changes to the cars has totally changed the dynamic of racing Sprint Cup cars at Daytona Superspeedway, and forced NASCAR into repeated changes before the season-opening and blue riband Daytona 500 on 20th February. The 2.5-mile oval, one of NASCAR’s two ‘restrictor plate’ tracks that require powerstrangling plates reducing the size of the engine carburettor inlets, was resurfaced last year, removing many of its notorious bumps. Combined with the latest tyre specification from Goodyear, drivers practising for the 500 discovered that not only could they effectively use much more of the track’s width, but that speeds were more than 10mph higher than has been normal at Daytona. Drivers also quickly latched on to the fact that two-car drafting pairs were much more effective than the previous large packs of drafting cars – the second car able to push or ‘bump-draft’ the leading car around the entire track and improve the speed of both. Changes to the noses of the Sprint Cup car, replacing the previous braced splitters with a moulded unit has made prolonged bump-drafting far easier. Speeds hit 203mph in practice, so before the 75-lap Budweiser Shootout exhibition race on Saturday 12th February NASCAR banned two cooling hoses in the engines, in the hope that drivers would be forced to break up two-car drafts sooner to prevent the engine of the second car overheating. The Shootout, however, was dominated by two-car drafts, with the highly visible speed differential between drafting pairs
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and single cars shocking to those who saw it. Speeds also climbed again, hitting 206mph at one point. As a result a raft of rule changes were made in the week between the Shootout and the 500 itself on 20th February, the last just as Race Tech was going to press. On the Sunday following the Shootout dramatic modifications were announced, again designed to put more pressure on engine temperatures and restrict two-car drafts. Front grille openings in the cars were reduced to 50 square inches (127 sq mm) – a
However, Sprint Cup drivers argued the only way to reduce the two-car draft was to make the cars faster and therefore more unstable when drafting. Hendrick Motorsports’ Jeff Gordon said the changes would make it easier to push a car in front. “Narrowing down the opening and installing the pressure valve, we’re not going to be able to push as long, but we’re still going to push,” he said. Teams also predicted that the changes affecting engine temperatures made accidents more likely, as drivers would LEFT Trevor Bayne (No 21 Ford) drafts David Ragan (No 6 Ford) on his way to winning the prestigious Daytona 500 (Photo courtesy Russell LaBounty/Autostock/Ford)
reduction of between 50 and 100 square inches dependent on manufacturer, and a spring-loaded valve added to the radiators to open at a specified temperature, releasing water from the engine. Engines would be set to run at up to 240 degrees – as much as 60 degrees lower than seen in the Shootout. Finally on Wednesday 16th NASCAR made its traditional speed-curbing change, restricting the size of the carburettor restrictor plate by 1/64th of an inch (0.4mm) to 57/64ths of an inch(22.6mm). This was predicted to cost around eight to 15bhp and 3mph in speed under drafting conditions.
have to pay far closer attention to their cars’ temperature gauges while trying to race in the wider, more rapidly changing drafting packs. Drivers generally backed the higher speeds at Daytona. Before the changes were announced Mark Martin, not a fan of restrictor-plate racing, told trackside media he had enjoyed the Shootout, despite crashing out. “I didn’t feel uncomfortable doing what we were doing,” Martin said. “I was having a good time. I don’t want to slow them down – I hope we don’t slow them down.” RT
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MCLAREN TO SUPPLY NASCAR’S FUEL INJECTION
By Andrew Charman
ABOVE Fuelling change: Lou Lutostanksi, vice president of sales and marketing at Freescale Semicondutor, Robin Pemberton, vice president of competition at NASCAR, and Peter Van Manen, managing director at McLaren Electronic Systems, announced the change to fuel injection at Daytona DAYTONA, FL: The NASCAR Sprint Cup series will make its much anticipated switch from carburettors to fuel injection at some point in the 2012 season, with the equipment being supplied by Formula One giant McLaren. The exact date is still to be decided and announcing the move, NASCAR vicepresident Robin Pemberton would not say that the systems would be used in all races afterwards, as it has not been tested with the ‘restrictor plate’ engines used to limit speeds at the Daytona and
Talladega Superspeedways. NASCAR has long shied away from using fuel injection because of the greater difficulty of policing systems compared to carburettors – in particular, preventing teams incorporating such elements as traction control. However, the perceived outmoded technology of carbs in a series which is manufacturer-dominated and used as a sales platform for road cars has swayed NASCAR’s hand. The single-injector systems will be
IN BRIEF NASCAR has radically changed its points system in a bid to put more emphasis on race wins. In future the 43-car field will score from 43 to a single point for their race result, with three extra points awarded to the race winner. The previous system saw the winner scoring 185 points, the scores decreasing by five, four and then three-point intervals through the field. The final two places in the season-ending Chase for the Championship will also be taken by drivers with the most race wins not in the top ten of points.
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Members of the engine department at NASCAR Sprint Cup team Joe Gibbs Racing escaped unhurt from an early-morning fire in the engine shop at its Huntersville base in North Carolina. Damage, mainly caused by smoke and water, was contained in a first floor room containing the team’s two engine dynos. Champing NASCAR Sprint Cup team Hendrick Motorsport has built a new outdoor pit crew training facility, including a six-lane 60-yard running track and 75-yard Astroturf field for conditioning training.
supplied by McLaren Electronics, part of UK-based McLaren Group which includes the McLaren F1 team, and Texas-based Freescale Semiconductor. Teams will buy their systems direct from McLaren at a price that Pemberton declined to reveal. McLaren has created an injection system that will be password-protected – any attempt to assess the internals by tampering with the password protection will cause the entire unit to shut down. Several NASCAR teams have been experimenting with fuel injection systems in recent months but will now have to adopt the McLaren version. Pemberton also confirmed that there was no current programme to extend the use of fuel injection to the second and third division Nationwide and Camping World Truck series, and that any change to these series would not happen for some time. Pemberton expects fuel-injected NASCAR engines to offer at least the same power level as carburettored ones. “It is a positive step that will provide more efficient engines, better performance and a greener footprint while at the same time maintaining the great competition we’ve had on the race track,” he said. RT
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Congratulations & Thank You to the ROLEX 24 at Daytona 2011 winners* and thanks to 77% of the entire field who used PAGID RS race pads.
One, Two overall winners: Chip Ganassi Racing / BMW Riley
GT class winner: TRG / Porsche GT3 Cup
GERMANY BT Bremsen Technik GmbH info@bremsentechnik.de www.pagid.com
USA BT Brake Technology pagid@braketechnology.com www.braketechnology.com
* overall position 1 to 7 for Daytona Prototypes and 1, 2 in GT class, all on PAGID RS racing brake pads.
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MOTORSPORTS PROFESSIONAL
RIGHT Comeback trail? Opel competed in the DTM until the end of 2006, latterly with its Astra here driven by Joachim Winkelhock. (Photo courtesy GM Europe)
OPEL BACK TO DTM?
By Andrew Charman
RÜSSELSHEIM, Germany: Opel is believed to be planning a return to the Deutsche TourenwagenMasters (DTM), Germany’s globally-known touring car championship. A senior source within Opel has told Race Tech that the giant German brand would likely take a decision on a return to motorsport within the next six months, and that Touring Cars would be favoured over rallying – the new International Rallying Championship is attracting significant manufacturer interest at present from the likes of Skoda. Opel’s parent General Motors (GM) is already represented in 2-litre Touring Car racing by Chevrolet, 2010 champions in both the World and British Touring Car Championships. The maker’s UK arm, Vauxhall, pulled out of the British series at the end of 2009. Opel was formerly a prime mover in the DTM, particularly following the series’ relaunch in 2000, but withdrew at the end of 2005 as part of major cost-cutting across Europe by GM.
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Since that date the existence of the DTM has been maintained by Mercedes-Benz and Audi, each supplying half the grid. However, the profile of the DTM has seen major boosts in the last year, with the announcement that BMW will join the series in 2012 with its M3, and that a
licensed American version of the DTM will launch in America from 2013, supporting the continent’s most successful motorsport, NASCAR. Six months ago the Williams Formula One team was strongly linked to an Opel DTM return, using the brand’s Insignia model. RT
PERSONNEL Having left the Renault F1 team at the end of last year, Bob Bell is joining Mercedes GP at the technical director at the start of April. Race Tech contributor and former engineering director of Renault F1, Pat Symonds is acting as a consultant for the Marussia Virgin Racing team. Tony George has been reinstated to the board of directors of Hulman & Co, the sole shareholder of Indianapolis Motor Speedway Corp, although he will not be directly involved in IndyCar racing.
Serio Rinland has stepped down as the technical director of Epsilon Euskadi to concentrate on his consultancy business Astauto. The services provided include a wide range of disciplines from the design and development of complete cars and/or components to aerodynamic, vehicle dynamics and structural analysis and development of existing vehicles using the latest technologies and simulation methods as well as managing whole projects. In the last few years, Astauto has been heavily involved in alternative energy developments, electric and hybrid car projects for racing and automotive applications.
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WORLD MOTORSPORT SYMPOSIUM JANUARY 2012
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This is the best forum to have an open discussion on the introduction in racing of road relevant powertrain technologies” Gilles Simon , Director Technical & Powertrain, FIA
A superb, thought provoking event that really got to the heart of the issues facing motorsport today as it grapples with the technology, cost and competitiveness condundrum” Lord Paul Drayson, team owner and former government minister
To me the engine day of this Symposium has been the best ever, especially with regard to the level of speakers and their presentations. The strong engagement of both speakers and the audience was really unique and encouraging to carry on in this direction” Ulrich Baretzky, Head of Engine Technology, Audi Sport
The World Motorsport Symposium presents a rare opportunity for like-minded engineers to discuss areas of the sport that they may not be so familiar with thereby expanding each other’s knowledge for mutual benefit, it is also an excellent networking opportunity” Pat Symonds
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ABOVE Ferrari’s drivers unveil the new car. But when it comes to launches, what you see isn’t always what you get (Photo: Ferrari)
Red BullRB7 THE RB7, unsurprisingly, is not very different to its predecessor. The trends of 2011 are those that Red Bull originated and it is not surprising therefore, that we are only seeing these enhanced on the RB7. Red Bull have very limited experience of KERS and, while they share many common parts with Lotus-Renault, there will be much to be learnt in this area. The KERS installation looks reasonably transparent but the sidepod inlets have been expanded, presumably to handle the extra cooling of the KERS system. The nose is lifted slightly and the top of the monocoque is consequently less sculptured. At the rear the pull rod suspension is retained but it seems as if the geometry is somewhat different with the pull rod to rocker pivot being lower, giving a better angle to the pull rod. I suspect that some of the secret to the good ride of the Red Bull on both full and empty tanks is due to judicious use of suspension rising rate geometry and this may be a further refinement in this direction.
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During the first test, they developed a long exhaust tailpipe aimed at blowing the outside 50 mm of the diffuser area, the section that can still remain open under the 2011 rules. The rear bodywork appears to be not much tighter than its 2010 counterpart although this in itself was extremely well executed and it was probably difficult to do more without a radical change
to the gearbox layout. Writing this as testing has just started I suspect that we will see many changes to the car before the season gets underway. It was Red Bull of course who surprised everyone last year by bringing the exhaust blown diffuser to the very last day of the final test, so sending their rivals rushing back to their (virtual) drawing boards! RT
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DARK NIGHTS & DARK FORCES! Pat Symonds guides us through 2011’s F1 contenders, plus lifts the lid on the subterfuge used by teams to trick rivals FTER A shorter than ever winter break, the teams set off for pre-season testing in Spain, their trucks full of new cars and their minds full of new ambitions. The restrictions agreed between the teams now limit the early testing to just 15 days and, with in-season testing a fading memory of the days of large budgets, every kilometre covered needs to count.
A
launches are no longer the extravagant affairs of days gone by, sponsors still hope that some form of release will garner valuable column inches in the press. To the designers who have worked all winter to conceal their work, the thought of showing it to the public and their rivals is an anathema. At the launch, studio-posed photographs are made available to the press. These images will have been arranged so that they show the sponsor decals in the best light while
PUBLIC SUBTERFUGE
disguising the technical detail as far as possible. Indeed the car that is photographed will generally be wearing the front wing from the previous model, as the detail in this area is one of the more closely guarded secrets. In fact, it is not unknown for the entire launch car to be a replica built from the engineering mock
Perhaps the most interesting aspect of winter testing these days is the lengths the teams go to in order to maintain confidentiality of their designs and indeed their performance, as long as possible. Although car
LEFT Red Bull’s RB7 testing (far left) and in the studio. Last season the team demonstrated their prowess in the gamesmanship contest by using decals of fake exhaust exits to throw rivals off the scent of their exhaust blown diffuser (Photo: Paul Gilham/Getty Images)
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up that will have been constructed over the winter to aid in the placement of wiring looms and driver controls. This year for example, Lotus Renault even released photographs showing the front of the sidepods to accompany their launch. Unsurprisingly, the innovative forward exit exhaust, which would have shown up in such a photograph, was not fitted. Once on the track, the physical detail is harder to conceal. Each team will commission a freelance photographer who will have been briefed to capture whatever close up shots of the opposition’s cars he can and will have been asked to focus on specific areas of interest to the team employing him. To counter this, mechanics are instructed to cover every area of interest
ABOVE Cover up: Red Bull mechanics fit a cover to the rear wing of the RB7 as soon as it comes to a halt in testing in Valencia (Photo: LAT)
McLarenMP4-26 LATE TO LAUNCH, they completed the first test with the old car. Bearing in mind that neither of their race drivers did the end of season Pirelli test, this was an interesting approach. While I have berated teams for not maximising track time with a new car, McLaren have the professionalism and pedigree to produce a new design that will achieve good reliability with minimum track time. Other than the dubious advantage of a few days’ extra design time, one positive aspect of the McLaren approach is to test the tyres on a known platform. If that platform is behaving differently, it can be assumed that the difference comes from tyre characteristics alone, not some nuance of
the chassis or aerodynamic map. The new car is perhaps most notable for the approach taken to the sidepod design. The inlets adopt what McLaren refer to as a ‘U’-shaped design. I do not know which of us is dyslexic, but they are clearly an ‘L’ shape! The purpose of course is the ever present quest for clean airflow to the rear of the car and, while others have paid a lot of attention to the lateral extremities of the pod, McLaren have provided a clean path for the air in proximity with the monocoque much as we did 16 years ago with the Benetton B195. It may not be the most aesthetic of designs but I know it to be very effective. They seem to have achieved this without compromising the undercut on the lower
outboard edge at all. The top of the outboard area of the pod is higher than would be found with a conventional design but I cannot see this being particularly significant. The nose of the car is high and wide and has a horizontal splitter beneath it. The steering rack appears lower than last year but otherwise the front suspension is relatively conventional, albeit appearing to retain the high degree of anti-dive that was present last year and that I feel did nothing to help their apparent ride problems. At the rear the fashionable pull rod suspension is used and the launch car diffuser appears very simple. I expect that will undergo some development prior to race one. RT
LEFT & BELOW McLaren’s MP4-26. The car is most notable for its sidepod design (Photos: Bellanca/Tee/LAT)
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Legend has it that when teams used to test at Mugello, thermal imaging devices were hidden in the vans of the hot-dog vendors�
FerrariF150TH ITALIA FERRARI have abandoned their inclined engine layout which is a natural consequence of the ban on double diffusers. Like Red Bull their car is a conventional development of the 2010 contender. The nose is significantly higher with the top surface of the monocoque now almost horizontal much further forward. Ferrari, like McLaren, have extensive KERS experience and it appears they have been able to package their system without significant compromise to the cooling inlets, although the sidepod volume appears to have increased significantly. In spite of this
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ABOVE The new Ferrari has a significantly higher nose than its predecessor (Photo: Ferrari)
they have managed to keep a reasonable undercut to the pods to aid airflow to the rear, although I had expected to see them be more aggressive in this area. The KERS itself is substantially developed from the 2009 version in both weight and packaging which should have allowed them to pull the bodywork in more. The rear suspension provides an interesting solution to the difficulty of cleaning up the airflow to the lower rear wing from above while retaining a clean flow along the top of the floor. Rather than opt for the pull rod solution, Ferrari have instead
retained a push rod but angled it forward to the extreme, thereby keeping the rear bodywork above the gearbox clean. Providing this has not introduced friction or lost motion into the system it is an acceptable solution. The front suspension is mounted to the high monocoque with no additional keel, leading to an even steeper angle of the front wishbones when compared to the F10. While front suspension kinematics still take a distant second place to aerodynamics, this is an acceptable, if unfortunate, compromise. RT
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MercedesMGP W02 FOR MANY this is one of the most eagerly anticipated cars of the year. In 2010 they were the best of the rest but that will not be an acceptable position for 2011. They have two good drivers and what I believe is the best powertrain in the field by way of a powerful engine and a sophisticated KERS system. The car itself looks tidy. The high nose is very chiselled and surprisingly wide. I suspect the width has as much to do with providing enough material to pass the front impact test as it has to do with aerodynamics. With such a
high under surface to the nose, the lower wishbone seems to be at a considerable angle to the horizontal plane, a characteristic I personally do not favour. The front wing, in early testing, appeared to be a development of the 2010 model but there were some nice touches such as the positioning of the cameras on the front wing pylons. The sidepod entries are quite large but very neat with plenty of undercut although the lower surface of the pods is quite wide further back. At the rear a pull rod layout is present and the
exhaust is firmly aimed at the very prominent starter motor access hole to maximise the blowing of the central part of the diffuser. The rear wing is endplate-supported and the lower rear wing straddles a rear impact structure that is placed above a simple five-section diffuser. The entire car looks very tidy, if somewhat conventional. In itself, there is nothing wrong with that and there is no reason why a simple, well-executed design should not be competitive. Time will tell. RT
BELOW With arguably the best powertrain in the field, much is expected of the Mercedes W02 (Photo: Mercedes GP)
Critical areas of the car will be disguised by means of a colour scheme that misleads the eye�
ABOVE Of course there are some reliability issues you just can’t disguise, as Felipe Massa discovered when his Ferrari hit trouble (Photo: Dunbar/LAT)
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with custom-made covers as soon as the car draws to a halt. During testing this is accepted practice, although at race meetings the sporting regulations prohibit the use of screens or covers that obscure any part of the car from view. In general, the photographs will be simple shots taken from as close as the photographer can get but in the past, teams have used highly specialised stereoscopic cameras from which, with knowledge of any given dimension on the car and the characteristics of the lens, the dual images produced can be used to make accurate measurements. Software is employed which automatically detects feature points in the two pictures and finds the matching pairs. It then uses these to calculate coordinates of the two lens positions and uses triangulation from the image to the focal plane to reconstruct the 3D scene. It is then possible to measure lengths and angles with a high degree of accuracy. Image capture is not just limited to the visible spectrum. Infra-red thermography is
regularly employed by the teams as they seek to determine tyre temperature distributions of their competitors as they enter the pits or even while circulating ontrack. Legend has it that when teams used to test at Mugello, a circuit owned by Ferrari, such thermal imaging devices were hidden in the vans of the hot-dog vendors parked around the circuit! CAMOUFLAGE Indeed Mugello was one of the first circuits to have multiple loop timing systems installed such that performance through discreet sectors of the circuit could be determined. Again, pit lane gossip had it that such data was made available to one team only. While stealth technology has not yet found its way into Formula One, visual disguise is not unknown. In its simplest form, critical areas of the car will be disguised by means of a colour scheme that misleads the eye. One of the best examples of camouflage seen recently was when Red
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BELOW King of spin: the most innovative design feature of the year, Renault’s forward exit exhaust, was nowhere to be seen when the R31 was unveiled (Photo: Renault/Ferraro/LAT)
Lotus RenaultR31 THIS re-emerging team have produced one of the more innovative layouts of 2011. The focus of discussion has been on the exhaust system, which is a perfect illustration of perverse thinking generated when rules are altered. The blown diffusers of 2010 provided a very noticeable increase in performance and rather than accepting that the rules have neutered this effect, Lotus Renault have found a novel solution by exiting the exhaust at the front of the sidepod floor and allowing the high-energy exhaust gas to energise the complete floor. While this may not provide quite the effect that was achieved last year, it has other advantages which can be seen by the extremely tight rear bodywork that can be achieved when it does not have to clear the exhaust system. The rear bodywork has very little exit area. There is a vertical exit on car centre line but the bodywork comes down very close to the diffuser. There will undoubtedly be variations to this when running in higher ambient temperatures. Also at the rear a pull rod has BELOW The R31 features tight rear bodywork and no centre wing pylon (Photo: Renault/Tee/LAT)
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been adopted for the rear suspension and the first iteration of diffuser seen in testing shows more use of strakes than was seen on the other cars. The rear wing is unusual these days in not having any centre pylon. At the front the nose is higher than last year but not as extreme as some. It has a more pronounced concavity to the upper surface. The steering rack remains aligned with the lower wishbone as last year, while the wishbone layout is also similar to the R30 with a zero keel and the outer joint of the lower wishbone picking up in the centre of the wheel bearing. The team have some KERS experience, having run their system in a few races in 2009. They have probably developed it further since then, particularly with regard to layout and trying to keep the centre of gravity down. RT
Bull introduced their blown diffuser during winter testing in 2010. Having run throughout the majority of sessions with what may be termed a conventional exhaust outlet, they ran on the very last day of the final test with the tailpipes moved to a lower position that energised the diffuser. To try to keep this fact from the casual observer, they made stickers that visually mimicked the previous exhaust outlets and attached them to the bodywork in the hope that the covert change would go unnoticed. The ruse had a life of just a few hours before it was spotted by eagle-eyed observers. This trend, of not showing the first race specification of the car until late in the testing, is a double-edged sword. It is a fact these days that designers push for the latest release date of the “race one” aerodynamic package. This is an acceptable risk due to the advances in CAE over the last decade. Reliability is generally designed in and advanced rig testing and instrumentation helps validate that design competence. However, when the concept steps outside
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ABOVE The design of the FW33 brims with innovation (Photo: Ferraro/LAT)
WilliamsFW33 EVERY BIT as innovative as the Lotus Renault is the Williams, where thoughts of making a compact gearbox to aid flow to the rear beam wing have been taken to extremes never before seen in a longitudinal gearbox. The differential and final drive have been lowered, with the consequential lowering of the top surface of the casing, to such an extent that there was no longer anywhere to mount the
inboard end of the top wishbone. This has been overcome by mounting the wishbone, which is actually a Zbone, onto the rear wing centre pillar. The angle of the driveshafts is the most extreme I have seen and will undoubtedly have required extensive proving of the constant velocity joints, probably on the sophisticated test rigs that Toyota have made available to the teams.
The innovation does not stop there however, as the roll hoop and engine air inlet has an interesting approach. The area of bodywork underneath the engine air inlet is severely cut back to the extent that it resembles the air horn that is normally housed underneath the engine cover. This has allowed much better blending of the surfaces to take place which, in conjunction with the driver’s helmet, will try and provide
Gamesmanship is an accepted part of pre-season testing and a huge amount of effort is put into trying to decipher it� the boundaries of common knowledge, then an assessment of risk must be taken. Red Bull were brave to race their blown diffuser after just one day of testing but it was a decision that became fully validated in that it presented no reliability problem to them throughout the season.
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The corollary of the late introduction of the true aerodynamic package is that subterfuge is less necessary. The teams can spend ages poring over their photographs but, if the true bodywork is yet to be released, that diligence is of limited value. The teams themselves will not suffer from
a strong flow to the rear wing. The front follows the normal trend of ever higher nose tips, this time with the cameras integrated into a hammerhead shark look-alike. The underside is steeply sculptured, thereby allowing a reasonable positioning of the front wishbones. The exhaust positioning looks as if it attempts to exploit the outboard 50 mm of the floor to aid the diffuser flow. RT
the late introduction as, providing the aerodynamic map shape is not significantly altered by the introduction of the update, the set-up work done in the early tests is still valid. General system reliability is also extensively investigated in the first days of running and it too is unaffected by later bodywork updates. Apart from the physical appearance of the cars, effort is often put into disguising the true pace. This, in my opinion, is of limited value as anyone involved in motorsport is by nature intensively competitive. The knowledge that you are quicker than your
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BELOW Force India’s VJM04 features a blade-type roll hoop (Photo: Force India)
Force IndiaVJM04
rivals does not lesson your efforts in seeking performance. Conversely, knowledge of a performance deficit cannot accelerate a development programme that is already at the operational limit of the team. Nevertheless, the gamesmanship is an accepted part of pre-season testing and consequently a huge amount of effort is put into trying to decipher it.
THE MOST noticeable feature of the 2011 Force India car is the adoption of the blade-type roll hoop. Andy Green has put together a neat package and, with the ability to exploit the Mercedes KERS system, they could be in good shape. The aerodynamic concentration has been to try to emulate the competitiveness shown on the faster circuits over the last two years at tracks
that require higher downforce. While the launch car showed nothing startling in the aerodynamic design, there is undoubtedly much in the pipeline. One ace that Force India have up their sleeve is that Jun Matsuzaki has joined the team from Bridgestone. Jun is an extremely good tyre engineer and I think his ability to understand the Pirelli tyres may play a significant role in the fortunes of the team. RT
LAPTIME BLUFF Fuel load is the obvious disguise. With each additional 10 kg of fuel slowing the lap time by over three tenths of a second, it does not take much to run what look like qualifying simulations with that sort of deficit built in. With lap times of the current cars so close, even this increment can place a car several positions down the pecking order. Similarly when doing race simulations that involve stops in the garage, true fuel loads are hard to determine. A race simulation that is done with proper pit stops and reaches its conclusion with no unscheduled stops due to car faults or red flags may be analysed but this is a rare occurrence indeed.
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ABOVE Jenson Button’s McLaren MP4-26 streaks towards his pit board. Many drivers go out of their way to ensure that their official lap times don’t give the game away (Photo: Dunbar/LAT)
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ABOVE A designer’s worst nightmare. Imagine the scene: you’ve worked all winter to keep your technical secret exactly that, then the PR team parade your work in front of hundreds of cameras! (Photo: Tee/LAT)
While the top teams will be downplaying their performance by running high fuel loads, it is not unknown for those lower down the order to do the opposite and run cars without ballast. Technical regulations do not apply during testing and the cars do not go through any form of scrutineering. In 1999, as Honda prepared for their return to Formula One they produced a car which was seen during winter testing. Its performance caused extreme embarrassment to many established teams and there were many suggestions that this car was running underweight at the tests. The accusations were never substantiated and indeed it seems the car was actually very fast. This did not stop various team principals objecting volubly that their performance was putting potential sponsors off! Tyres too of course play their role, particularly this year with the high degradation seen on the Pirellis in the early tests. A low fuel run on tyres with just a couple of laps on them will look like a run on new tyres but will fall short of the ultimate by some tenths. Interestingly it was one of the tyre companies, Michelin, who cut
through a lot of the deception of Formula One testing when they were competing against Bridgestone. They actually managed to get all their teams to sign up to an information sharing protocol whereby each informed Michelin of their running fuel loads and exactly what set of tyres they were using. Every evening at both tests and GP event practice days, the Michelin engineers would collate the information and make it available to all their teams. MIND GAMES Even without resort to physical trickery, drivers can play a part in the deception and will often deliberately back off in a particular sector of a lap to disguise their pace. On subsequent laps they will back off in different areas so that, while they have knowledge of how their car is at full pace throughout the lap, observers are unable to piece together the true pace with any reasonable accuracy. One driver I have worked with would even do this during official practice sessions at race events but would never admit it even to his team-mate who he was easily capable of beating without resort to subterfuge!
SauberC30 LIKE THE Ferrari, the Sauber has slightly boxy sidepods by the demanding standards of 2011 and one wonders if the needs of the Ferrari-supplied KERS are responsible for this. As with most cars, the nose tip has been lifted but there remains a large concave top surface. The front suspension impresses me with the lower wishbones picking up on small, aerodynamically sculptured, stubs beneath the chassis which reflect the shape of the ubiquitous undernose strakes. This leads to what I think are better front suspension kinematics than most others will have obtained. The splitter area and pod vanes, at least in the early testing, seem to be the same as were seen on the C29. The headrest and roll hoop air inlet area has obviously benefited from a great deal of attention and the detail in this area,
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somewhat reminiscent of a McLaren, is particularly good. At the rear, they have adopted the very forward-angled push rod as seen on the
Ferrari, coupled to forward-mounted dampers. The exhaust is low to the floor but does not appear to have anything particularly novel about it. RT BELOW The Sauber C30 could benefit from good front suspension kinematics (Photo: Sauber)
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ABOVE One of the surprises of the season: Toro Rosso produced a new car concept, exploiting the airflow region beneath the sidepod (Photo: Peter J Fox/Getty Images)
Scuderia Toro RossoSTR6 AS THE TEAM find their design feet, they have produced one of the surprises of 2011. A neat car was always expected from the team but not a new concept and yet that is exactly what they have come up with. The sidepod arrangement is beautifully
smoothed and sculptured and, by raising the radiators by approximately 12 cm, they have exploited an airflow region below the pod to feed high-energy air over the diffuser. The flat floor of course shadows the raised pod to maintain legality in a design reminiscent of the 1991 Ferrari. RT
BELOW Red Bull mechanics wearing rubber gloves as a precaution against KERS. The energy recovery system adds an extra variable this season (Photo: Dunbar/LAT)
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THE ROUTINE It is of some surprise that with such limited pre-season testing some teams choose to wait until the second test to bring their new cars to the track. Missing the first test means a reduction of 20% of the available track time. Bearing in mind that even Spain can be cold and wet in February, there is a real possibility of further climatic restrictions to running. Designers always fight for the maximum time they can get to perfect their product but the reality is that, over a project that has a duration of more than 200 days, the difference between attending the first test and the second test is a mere eight days. These days much of the durability testing that has led to the phenomenal reliability records of current Formula One cars takes place on increasingly complex test rigs. This should however, be regarded as a necessary precursor to track testing, not a substitute for it. It may be argued that the better-funded and more experienced teams are better placed to manage this risk but even so I think it is a questionable decision. For the smaller teams, that
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Team LotusT128 A MAJOR step forward for the Norfolk team with a car that displays the benefit of having had much more time lavished on its design than did its predecessor. In spite of the restrictions placed in the rules to limit blade-type roll over bars, Lotus have adopted a blade design that is fully compliant with the 2011 regulations. Either side of it are upper inlets for the engine air and lower inlets for cooling purposes. The front of the monocoque looks to be as high as the rules allow but the nose top surface droops more than most. The lower surface seems to have a simple wedge shape with quite high suspension pick ups. Last year’s car was very heavy, a penalty no doubt of the haste with which it had to be designed. This year the car has to carry ballast to make the weight, resulting, no doubt, in a significantly lower centre of gravity. Pull rod rear suspension has been adopted, a natural consequence of using the Red Bull gearbox mated to the car’s new Renault engine. All in all, this looks like a credible car which should achieve the team’s ambition of regularly mixing with the midfield runners. RT
BELOW Team Lotus steps up a gear with the T128
RT
HRTF111 THE HRT has, at the time of writing, only been seen in virtual form. One expects that Geoff Willis, aided by Paul White, will have concentrated their small budget on righting
some of the wrongs of last year, particularly with regard to the aerodynamic characteristics of the car, as well as the ever present quest for pure downforce. RT
ABOVE HRT’s F111 wears a new livery by ‘Tron’ movie designer Daniel Simon (Photo: HRT)
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Marussia VirginMVR-02 THE TEAM are gearing up for bigger things in 2011 with a firm commitment to succeed. WR Technology have delivered a car that looks a good evolution of their first effort and appears to have attention to the correct details. The diffuser is blown by the exhaust for the first time, in spite of the limitations of the
generally have poorer reliability, it would seem essential to maximise track time. The first test of any new car is an exciting and anxious time for the designers and engineers. Much of the first few days will be dedicated to system tests and close inspection of components that may be subject to fatigue failures or unexpected overloads. Even with ever more sophisticated CAE tools and multi-channel vibration testing rigs, there will always be something unexpected to ruin their day! Generally, the run length is slowly built up from the early short duration exploratory laps to a point where full race distance simulations are being carried out by the end of the testing. The short runs are necessary to allow close scrutiny of the physical components of the car and the long runs are required to ensure that features such as heat soak do not have an adverse effect on any element. The system tests have to cover every eventuality and condition that may be met. They range from the simple and obvious, such as running out of fuel to ensure every last drop of the precious fluid is scavenged from the tank, to simulating many starts with long hold periods on the “grid”. The full range of settings of all systems needs to be tried to ensure that they function correctly and reliably. For Subscribe +44 (0) 208 446 2100
2011 rules, and it appears that there are a number of options available in this vein. The team need to find the balance between speed and reliability but, with some experience onboard, they are quite capable of making their target of regular Q2 appearances. RT
example, it is of no use to spend the whole of testing with a diff map that only uses low clamping pressure and then finding that when higher clamping pressure is required in an early race hydraulic seals start failing. CARDINAL SIN Many will remember the embarrassment of the Stewart team in Australia some years ago when both cars were engulfed in a cloud of smoke as they sat on the start line for the first race. In that particular instance they had not skimped
ABOVE Virgin’s MVR-02 adopts an exhaust-blown diffuser
a full race specification in time to get significant mileage on every component. On top of all the general housekeeping of ensuring that the car behaves as expected and has the reliability that is always hoped for, the engineers will be pushing the performance envelope to make certain that they understand the car and how to extract the best possible lap times from it. The nuances of how it uses its tyres over a single qualifying lap and over a race distance stint are far better learned now than in the restricted environment of the first grand prix. For the fans, and indeed for the
Drivers often deliberately back off in a particular sector of a lap to disguise their pace” on their system checks but they had committed the cardinal sin of not testing the same specification of car build that they took to the first race. A simple change of supplier for a small heat shield led to a very public embarrassment. Herein lays a source of continual argument between the trackside engineers and those back at base as they try to put the car into
competitors themselves, the winter tests spark discussion about who will win and who will disappoint, who has been innovative and who has been conservative. Journalists these days are more wary of trying to predict outcomes from data that has statistical insignificance but equally it is hard to resist the temptation of reading more into events than is truly possible! RT March 2011
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COVER STORY LOTUS EVORA GTE
THE CAR THAT LURED LOTUS BACK TO LE MANS Chris Pickering charts the development of a GT racer that puts Lotus on a collision course with endurance racing’s most successful manufacturers
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HAT YOU see here is the Lotus Evora GTE. It’s the latest addition to one of the fastestgrowing families in motorsport. Go back just a few years and Lotus was quietly knocking out road cars in the depths of Norfolk with little more than the ghost of Colin Chapman lingering in professional-level motorsport, but all that’s changed. And rather dramatically. In the blink of an eye the company has gained a presence in Formula One and IndyCar, as well as the GP2 and GP4 feeder series. There’s also said to be an LMP2 car in the pipeline for next year, and that’s before you even consider the on-going rise of the Lotus Cup clubman’s series. We’re not entirely sure what they’ve started putting in the water at Hethel, but it’s clearly working; Lotus is on a roll, and in fact so prolific is the company’s motorsport division at the moment that it’s spawned not one, but three competition variants of the new Evora road car. The first step on the Evora competition ladder is the GT4, built to SRO rules for championships like the GT4 European Cup. It features a Cosworth-prepared version of the road car’s naturally aspirated 3.5-litre Toyota V6, which uses a long-stroke crankshaft to increase its capacity to 4 litres. A raft of airflow
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improvements, as well as new cam profiles and a specially calibrated Pectel ECU push the power output to 360 PS and torque to 445 Nm. However, it actually remains very close to the road car. Following an FEA study Cosworth elected to retain many of the standard components, including the pistons and valves. Similarly, much of the rest of the GT4 is carried over from the production model. In fact, besides the addition of a roll cage and a six-speed sequential gearbox, most of the modifications are
detail changes to what remains a fundamentally production-based racer. Beyond the GT4 sits the Endurance. This is closely related to the GT4, but it features a number of aerodynamic tweaks, including a new front splitter, a larger rear wing and a revised diffuser. The engine
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receives larger valves, a revised crankshaft and new manifolds to take it up to 440 PS and, like the GT4, it runs a dry sump system, which allows the car to run lower, as well as maintaining vital lubrication. At the same time, lighter doors and roof panels see the weight drop from 1,200 kg to 1,150 kg, while bigger brakes add to the stopping power. What follows next is a big jump to the Evora GTE. The ACO class from which it takes its name is effectively the old GT2, and it sets the template for GT cars at Le Mans and other ACO-sanctioned events for the foreseeable future. That means a significantly higher level of development – and indeed cost – for the cars. 80 PER CENT RACECAR “If the GT4 and Endurance are 80 per cent road car and 20 per cent modified, then the GTE is 80 per cent race car and only 20 per cent standard,” Lotus Motorsport director Claudio Berro tells us. And it’s borne out by the figures. The difference between the GT4 and Endurance models is around four seconds a lap, but Lotus’s simulations
predict the GTE will shave a further six seconds off this. Considering they’re both slick-shod GT racers of the same fundamental design, this is a huge step up – it becomes increasingly difficult to eke out the performance, and the modifications
“We looked carefully at the intake design. You’re limited to the sonic speed through the restrictor, but there are things we can do to try and make best use of that. Ultimately, the presence of a restrictor means the power the engine can develop is
The transverse engine location brings a unique set of challenges and opportunities” have been far-reaching. The ACO uses air intake restrictors and weight limits to balance the performance of cars in the GTE class, so the headline figures aren’t perhaps as different as you might expect. The power rises by a modest 40 PS to 480, but the real changes lie in engineering a car for 24-hour durability. “It’s obviously important to reduce friction and inertia, but you don’t want to take away too much material on an engine designed to last for 5,000 kilometres of endurance, so it’s a case of balancing performance and reliability,” Berro comments.
limited by the valve diameter. The sixcylinder Evora – like the Porsche 911 – has a slightly smaller valve area than the eightcylinder Ferraris, BMWs and Corvettes, which means it’s slightly harder to develop the power but, at the same time, it’s expected to consume less fuel, which is extremely important in endurance racing.” Cosworth has been understandably coy about the exact spec of the GTE engine, but the changes are said to be comprehensive. There is, however, a price for all this development. Despite their shared architecture, the GTE engine costs
ABOVE A rendering of the Evora GTE that will carry the Lotus name back to Le Mans
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COVER STORY LOTUS EVORA GTE
The aim was to combine the lowered chassis with the same ‘kinematic concept’ applied to the other cars”
ABOVE The GTE is designed to replicate the GT4 racer’s good handling traits twice as much to build as the GT4 unit, and it’s a major contributor to the car’s £450,000 price tag (the Endurance, in contrast, tips the scales at £150,000 and the GT4 at just £120,000). Of course one of the biggest questions about the naturally aspirated V6 is why the competition-spec Evoras use it in the first place. The halo model in the road car range is the supercharged Evora S, so why didn’t Lotus use that as the basis for its GT racers? “With the Evora S coming out we did look at using forced induction,” confesses Berro. “However, the power lost to the compressor can be quite high and, while this isn’t much of an issue if you’re
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running under mixed load conditions on the road, it becomes far more significant if you’re flat-out all the time on the track.” What’s more, the ACO applies an equivalence factor of 1.7 to the capacity of forced induction engines, so the Evora S road car’s 3.5-litre capacity would effectively become 5.95 litres in the scrutineers’ eyes, which would move it into a higher minimum weight category – something Berro wasn’t keen on. “The Evora’s finest attribute is its [lack of] weight. It’s this which helps it to turn-in and transition between the corners so well,” he comments. “By going for a higher weight limit we’d have lost some of
that without any real benefit in return.” As with the road car, the racing Evoras’ chassis are composed of three parts: a central tub and two subframes. The basic structural core of the tub is the same across the range, but the subframes – standard road items on the GT and Endurance – receive substantial changes on the GTE. The wishbone mounting points are raised to run the car as low as possible, with less than four centimetres of ground clearance remaining. Plus, to make the most of the GTE aero rules the track has been increased by 100 mm by using longer wishbones. “By changing the suspension mounting points and the wishbone length we’ve
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COVER STORY LOTUS EVORA GTE
ended up with a completely different geometry, with a whole new set of kinematics, but we still wanted to retain the handling characteristics of the standard car,” Berro explains. “The GT4 and Endurance run almost the same geometry as the road car. The only significant difference is that they run 3.5 degrees of camber on the rear instead of 2. Their handling is very good – particularly in terms of turn-in and the level of mechanical traction. We wanted to engineer those same characteristics into the GTE, but using the standard geometry was no longer an option on the GTE, with its fundamentally different mounting points.” Berro and his team went back to the drawing board to define the new mounting points. Their aim was to combine the lowered chassis with the same ‘kinematic concept’ that had been applied to the other cars, and the work has – they hope – been a great success. (“We will see when the car gets to the track for real,” quips the affable Italian.) BELOW The Jetalliance team that will campaign the Evora GTE is no stranger to Le Mans. Its Aston Martin DBR9 finished third in the GT1 category in 2009 (Photo: Gibson/LAT)
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One of the most significant upgrades that goes into the GTE is its tyre area. The front wheels grow from 8.5 inches wide (on the GT4) to 12, while the rears are now 14J x 18. This, along with the extra power, the increased downforce and a higher minimum weight limit of 1,245 kg leads to significantly increased suspension loads. What’s more, the GTE is built with the prolonged stress of 24-hour events in mind. The wishbones are totally redesigned and made from chromium molybdenum steel (25CD4) – in place of the other models’ production-based aluminium unit. Similarly, the uprights, which now come in forged aluminium, feature larger, stronger hub bearings. “Reliability is key for 24-hour races,” Berro observes. “The standard road car units are perfect for the GT4 and Endurance, with their reduced weight and lower cornering forces, but the demands of 24-hour racing mean they needed to be uprated for the GTE.” Unlike its siblings, the GTE does away with
the standard engine location. In line with Lotus’s concerted effort to reduce the centre of gravity height, the V6 is lowered within the chassis. It’s also tilted forward to further reduce its height, as well as to push the mass forward. SWIMMING AGAINST THE TIDE The Evora is unique in the GTE class for using a transverse engine location. Irrespective of whether they place in front or behind of the driver, all the other contenders mount their engines longitudinally. The difference brings a unique set of challenges and opportunities, Berro explains: “In some respects it would have been easier to get the right weight distribution and centre of gravity with a conventional longitudinal engine. However, with the Evora the mass of the engine is located almost directly above the rear wheels, giving it very good mechanical traction. It’s going to be
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COVER STORY LOTUS EVORA GTE
interesting to see how it compares to the Ferraris and Porsches on the track. It may well be that there isn’t much difference in the dry, but the Evora has a bit of an advantage in the wet...” This engine location also changes the gearbox configuration. With a conventional layout you need conical gears to rotate the drive through 90 degrees before it goes out to the driveshafts, but with a transverse engine the propshaft, gearbox and driveshafts can all run parallel. This means you can run cylindrical gears, Berro explains, which reduces drive losses and produces a more compact layout. Of course, repositioning the engine means the gearbox mountings have to be
adapted too. All three variants of the Evora have the same basic six-speed sequential dog-engagement gearbox produced by Xtrac. Crucially, however, the GTE benefits from a number of internal revisions to cope with the additional mechanical stress generated by the top spec car’s higher weight and torque. The gearbox features its own semi-dry sump, force-fed lubrication system, complete with an internal gerotor pump and an external oil cooler. Another important aspect of the transverse layout is the fuel tank location. It’s a one-piece unit mounted across the car behind the driver’s seat – the same as the road car (where it sits under the rear
ABOVE & BELOW Lotus won its class of the once-coveted Le Mans Index of Performance in 1957 with the Lotus Eleven. In recent years, its presence was confined to the ‘Le Mans Legends’ event (Photos: LAT & Bloxham/LAT)
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seats). This is, in itself, somewhat unusual. The rear-engined Porsches position the tank at the front – which works very well under certain conditions, but causes the balance to shift as the fuel load changes. Similarly, the longitudinally-mid-engined Ferraris have their own idiosyncrasies. They use twin tanks: one either side of the engine, with a relatively small connecting hose between the two. “This means they take longer to fill than a single one-piece tank,” notes Berro. “If you can complete each refuelling stop five or six seconds faster than the other teams, then over the course of a 24-hour race you save two minutes.” That might not sound like much, but it’s half a lap at Le Mans and a full lap around some of the shorter circuits. The wide, low wedge of the Evora bodywork was another area of development on the GTE. Under the ACO rules, manufacturers are allowed to substitute lesser composites – such as the GRP body panels on the road-going Evora – with
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You’re limited to the sonic speed through the restrictor, but there are things we can do to make best use of that”
ABOVE The Evora brand is already well represented in GT racing, but the GTE will spread the marque’s influence as far afield as the American Le Mans Series and Japan carbon fibre. Lotus set to work with YCOM on the production of the panels, and eventually the doors, roof, bonnet and bumpers all received the carbon treatment, while ironically – due to a quirk in the rules – the Evora’s aluminium-bodied competitors have to retain their original metallic panels. All three iterations of the car were subject to CFD studies to help sculpt their bodywork. “Working with CFD made it much easier to remain within the cost control limits,” says Berro. “We didn’t need to prepare wind tunnel models or pay for tunnel time, so it was far more cost-effective. It allowed us to develop the car further than physical testing would have for the same budget.” Compared to the Endurance model, it’s largely a case of detail improvements on the external aerodynamics, but things do change more inside. The cooling requirements are higher in GTE spec and they’re a particularly critical factor in longdistance racing. The lessons learned from extensive CFD modelling were used to
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finesse the flow around the intake and extraction vents, as well as the heat exchangers themselves. The aim was twofold. Firstly the engineers wanted to improve the heat transfer, but, at the same time, they were careful to minimise any drag penalty it might incur. AERO BALANCE The ACO rules state that the car must use the same basic aerodynamic package for all circuits, which makes the task of designing the aero package somewhat challenging. You have to strike a fine balance between downforce and drag, which becomes particularly difficult when one of the tracks it’s designed to compete on is Le Mans, with its long straights and fast sweeping corners. Ultimately, much of the aerodynamic development is constrained by the rules. The Evora GTE is due to make its first foray on track later this month, when it begins testing with the Jetalliance team. Its first
competitive outing is expected to be the Spa six-hour race in May, and the team plans to contest all subsequent rounds of the InterContinental Le Mans Cup, as well as the Le Mans 24 Hours itself. But there’s more to come from Lotus – quite literally. “We plan to produce between five and 10 cars in total,” says Berro. “Two of them are bound for Jetalliance; car number three will become Lotus’s own development car; and there are two more pencilled in to go to America (for the ALMS) and Japan (to compete in the Japanese Super GT series).” Taking Lotus back to top-flight GT racing is clearly a challenge that Berro has relished, but he’s not underestimating the task ahead. “When the Evora takes to the track we’re going to be up against the top five endurance racing manufacturers of the last three decades,” he says. “For us, everything is new – that’s the biggest challenge... We’ve done everything we can within the rules to prepare the car and now we must wait and see.” RT
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WHY MOTORSPORT MUST INNOVATE
INNOVATE OR FADE AWAY Lord Paul Drayson, former UK government minister and now a Le Mans team owner and successful entrepreneur, set the theme for Race Tech’s World Motorsport Symposium: how will motorsport embrace its future? By William Kimberley
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BELIEVE we are at the beginning of the most interesting and exciting time for both the car and motorsport industries,” claimed Lord Drayson in his keynote speech to open the World Motorsport Symposium. “Now that I’m back in business as a science entrepreneur, I’m working on a number of different projects in science and technology. However, I can give you a perspective on motorsport as someone who is absolutely passionate about it as a practitioner but with the perspective of other industries. “Having been the science minister for two years, it gave me a great insight about what’s hot in technology, globally, what’s important in terms of science and engineering change and what’s really making a difference to the planet. I also learnt which market sectors are having the biggest impact on changing society and creating wealth.” He then commented on how rapidly the world is changing, geopolitically, economically and technologically. “The Chinese have a saying which is ‘may you live in interesting times’ and it’s never been more interesting than it is now. The pace of change taking place has never been faster. “We’ve seen massive shifts of economic
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ABOVE Lord Paul Drayson delivers his message as a keynote speaker at Race Tech’s World Motorsport Symposium and political power from the West to the East. The recognition, at last, of the global importance of climate change, and unprecedented volatility in commodity prices in not just oil but also copper and food – the Russians are not exporting wheat, which is having a devastating effect on food price. “Then there was the near collapse of the Western financial system in 2008 and we’re now in the middle of an economology bubble. Facebook was recently valued at $50 billion. We’ve also had this horrendous crisis within the automotive industry that in part was triggered by the financial collapse. After General Motors’ bankruptcy we then saw it had the biggest Initial Public
Offering in history with $23 billion while GM stock is now trading 15% up today compared to the price last year. “The answer to the question of why the car industry is suddenly hot again is, I believe, because it’s seeing the return of innovation. When governments throughout Europe pumped in huge amounts of taxpayers’ money to save large parts of the automotive industry, they expected a price, and having been a government minister at the time, that price was all about accelerating the transition to low carbon.” Drayson then spoke about technologies that the automotive industry will have to embrace if it is to have a sustainable future, specifically highlighting a quote from
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Steven Chu, the US Energy Secretary, at a climate change conference in Cancun in December. “This is someone who was awarded the Nobel Prize for physics in 1997 so what he says is important and what he said in Cancun was that he expects electric cars to be competitive with petrolpowered ones by 2015. If he’s right then we are about to witness a disruption in the global car industry that is more momentous than anything we’ve ever seen. “We know that those in the car industry are aware that the drivetrain is changing, but the question is what is it changing to? No-one knows the answer. No company can have the resources or expertise, no matter how big they are, to cover all of the various technology options that are now open to us.” MASSIVE CHALLENGE He then listed the technologies that included alternative fuels, electric vehicles, hydrogen fuel cells, turbines, hybrids and combinations of these, as areas of major development in the automotive industry over the last few years. “However, no-one yet knows which one is going to emerge to dominate the next 50 or so years. This presents a massive challenge to both the automotive industry and to governments
that have invested so much money and which are committed to reducing their reliance on oil and the carbon emissions from road transport. “It means that we have to look at other industries to get a sense of what our future
understanding of biology, not chemistry, enabled a man-made copy of a human substance to be made – and the world was never the same again for both diabetics and the pharmaceutical industry. “This new understanding of genetics
Times of unprecedented change and innovation put the motorsport industry at a crossroads” is likely to be. I worked for 15 years in the pharmaceutical and biotech industries and I think there’s an analogy for us. Prior to the 1970s, the global pharmaceutical industry was dominated by a small number of European and US companies. Their core competencies and successes were built on understanding medicinal chemistry – the chemistry of discovery and development and new compounds, making drugs from new chemical entities or discovering naturally occurring ones like aspirin. “This world was absolutely shocked when a tiny biotechnology company in California first made synthetic human insulin in 1978, making an analogue of a human hormone inside a test tube. What this meant was that for the first time an
was not found in a big company but in a tiny one. Large businesses own the route to market because they understood the customer but they don’t always have the technology. I believe the same is going to happen in the car industry and the impact on motorsport will be huge. However, I don’t think large companies should feel threatened. If we look at the pharmaceutical experience and that small company that made the human synthetic insulin, it eventually grew to a multibillion dollar business that was bought by Roche, an old mainstream pharmaceutical company. “So I hope that future Colin Chapmans will be given the opportunities to apply the breakthrough thinking to build their
BELOW Porsche has showcased motorsport’s innovative capabilities with the performance of its 911 GT3 R Hybrid, utilising a system designed by Williams Hybrid Power (Photo: Porsche AG)
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businesses through that and then collaborate or be acquired by the larger company. I think, for example, there’s going to be a huge market for making small runs of prototype vehicles because the cost curve that the major automotive companies have gone down to optimise the current ways of manufacturing cars cannot be easily transferred to new technologies.” He then pointed out that the major difference between the pharmaceutical and motorsport industries is that while one is answerable to the customer and market demands, the other is governed by the rule book. “In racing, innovation is constrained or encouraged by the rules and the regulators determine via the rule book how fast that innovation happens,” he said. “Given that we are living in times of unprecedented change and innovation
LEFT The GT1 World Championship relies on performance balancing to enhance its spectacle, but it’s a trend Drayson is critical of (Photo: Staley/LAT)
that is affecting the mainstream automotive industry, this puts the motorsport industry at a crossroads. “The thing that’s really interesting for aerodynamicists and chassis engineers is that many of these technologies are really disruptive. When you start thinking about alternative powertrains, for example, and the possibility of re-thinking the shape and
weight distribution of the car, then anything’s possible. If you don’t need one lump that needs to be positioned in the centre of the chassis but rather have electric hub motors, it gives you a whole new smorgasbord of options with chassis design. I think that this in itself is going to provide us with huge opportunities to make greater contributions to the development and
I hope that future Colin Chapmans will be given the opportunities to apply their breakthrough thinking” BELOW Drayson believes motorsport’s regulations must change to encourage innovation. For instance, why not develop a hydrogen fuel cell for the air conditioning on an LMP car? (Photo: DPPI/Peugeot)
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The question is whether the rules will change fast enough to make sure that motorsport remains relevant?”
ABOVE The threat to the magnificent Spa-Francorchamps circuit underlined the fact that motorsport does have enemies (Photo: Etherington/LAT)
understanding of alternative technologies. After all, this has always been the prime justification for investment in motorsport. “The question is whether the rules will change fast enough to make sure that motorsport remains relevant and allow our businesses to continue to grow. Unfortunately the rise of marketing power and the need to control costs in the recent past has meant that much of the sport today is driven by the marketing budget and by sponsorship. It seems that way of motivating people to buy things today is to inspire them through the spectacle and not so much as it was in the days of Colin Chapman which was about the engineering innovation. I believe we need to get back to the way it used to be. “However, I recognise that there has to be a transition over time but if Secretary Chu is expecting 2015 to be the year when the performance of the electric car equals that of the petrol car, then why not a mission statement that gives a similar performance comparison in terms of Formula One? What would it take to build an F1 car that has the performance of a 2011 car but does not use the internal combustion engine? “I believe that incentives should be offered to develop the new technologies and I think it’s inescapable because we have had
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huge investment in the optimisation of current technology and therefore it’s not going to be competitive unless some way is found of balancing the two. However, I don’t believe it should be done through some sort of performance balancing. For me, putting ballast on a racing car is completely mad. Instead I think there should be some sort of financial balance and finding some way of encouraging the investment to go into this area to accelerate it but within a planned timeframe so that people can really organise it. For example, how about a rule to encourage the use of a hydrogen fuel cell for air conditioning in a Le Mans car? It’s things like this that need to happen more quickly.” TIME IS RUNNING OUT Drayson believes time is running out for motorsport and that fundamental issues will have to be addressed that will decide its future. “We have come to a fork in the road. On the one hand we can go down the route where we make a massive contribution to the green arms race, act as a spur to the pace of innovation with new materials, technologies and processes. On the other hand, we can continue to be dominated by marketing with single-make series making up the majority of the sport.
If motorsport is to go this way, though, I believe that over time it will become increasingly irrelevant and introspective. If the regulations remain too limited then the innovation that the public are going to see taking place in their road cars will not be mirrored by that taking place on the race track.” However, he is hopeful that the governing bodies are responding, quoting the FIA establishing the Alternative Energy Commission of which he is a member. “I think we need to recognise that this flexibility will not happen overnight and, of course, cost is very important, particularly at a time when we are coming out of a downturn. However, I really am worried that things are not moving fast enough.” He also pointed out that not everyone is a motorsport fan, and indeed it has its enemies. “We need to recognise that not everyone loves motor racing and we’ve had a taste of what happens when those people who don’t like it impose noise limits around circuits. To think that SpaFrancorchamps nearly lost its licence is a huge wake-up call. The world is worried about energy and climate change and we as an industry need to take that more seriously and get ahead of the argument so that we go back to being a racing laboratory for new technologies.” RT
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ENGINE TECHNOLOGY RACE ENGINE DESIGN PART 4
DESIGN BY LIMITATIONS John Lievesley uses camshaft positioning to illustrate a design technique he favours, plus proposes an experiment that could well damage your marriage!
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TECHNIQUE that I have often found useful, I call “Design by Limitations”. Positioning the camshafts will be a simple introductory example of its use (see Figure 1). In article two we established that the minimum centre distance of the camshafts was a build up of: camshaft shaft diameter = 28 mm; the outer diameter of the spark plug tower = 30 mm, locally proof machined if required by 0.5 mm deep at camshaft closest approach; and that there should be a general minimum running clearance of 1 mm. Hence the minimum distance between the camshaft C/L and the spark plug C/L will be: ½ x (28 + 30 +2x(1 - 0.5)) = 29.5 mm. Plot two vertical lines spaced 29.5 mm either side of the plug C/L, one for each cam. We have derived Limitation 1: the camshaft C/Ls must lie on or outside these lines. Estimate a base circle radius of 14.5 mm for the inlet lobe (0.5 mm bigger than the shaft radius) and a rocker pad thickness of 2.5 mm which is generous but can be reduced later. Plot an arc, parallel to the provisional top profile of the inlet rocker arm, at a radial distance of 14.5 + 2.5 = 17.0 mm. We have derived Inlet Limitation 2: the inlet camshaft C/L must lie on or above this arc. In article two we established a maximum inlet valve lift of 15 mm, which corresponds to a cam lobe lift of (15/rocker ratio) + 0.25 ‘tappet’ clearance = guesstimate 12.25 mm.
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Adding 14.5 mm base circle radius from limitation 2 gives us an inlet lobe swept radius of 26.75 mm. We also established an outer diameter of 30 mm for the valve spring = 15 mm radius from the valve C/L. Plot a line parallel to the valve C/L at a distance of 15.0 – 26.75 = -11.75 mm. We have derived Inlet Limitation 3: the camshaft C/L must lie on or inside this line. We now have a short arc and two lines which collectively fence the potential lowest positions of the inlet camshaft C/L. In Figure 2, I have chosen a position 30 mm from the engine C/L and 156 mm from the cylinder head face for no better reasons than that they are whole numbers and close to the lower limitation line. The corresponding inlet lobe base circle radius = 14.581 mm, the maximum swept radius = 26.831 mm and there is extra clearance for the lobe swept radius of 1.341 mm giving plenty of room for development. We can now answer the question of how to accommodate the variation in height between the inlet and exhaust rocker arm surfaces, by using a similar process to that used above for the inlet camshaft centre, to define the exhaust camshaft centre. “Keep it simple, stupid”, therefore for ease of manufacture the Y coordinates of the centres of both camshafts should be equal. By so doing, the top and bottom faces of the cylinder head are made parallel to each other, giving straightforward machining and Exhaust Limitation 1 (Figure 2).
In Figure 1 we have already drawn a vertical line, parallel to the spark plug C/L and 29.5 mm from it, labelled as ‘Exhaust Limitation 2’, the innermost limitation of the exhaust camshaft X coordinate. This corresponds to a cam centre at X = 31.532 mm which in Figure 2 we round up to 32.0 mm, leading to a base circle radius of 14.809 mm and an instantaneous rocker ratio, scaled from the sketch, of about 1.6:1. In article two we established a maximum lift of 12 mm for the exhaust valve, which corresponds to a cam lobe lift of (12/1.6) + 0.25 ‘tappet’ clearance = 7.75 mm. Adding 14.809 mm from above gives a maximum swept radius = 22.309 mm and in Figure 2 the lobe looks sensible, just slightly larger than the inlet. Exhaust Limitation 3 is derived as follows: see Figure 3. The lobe centre X coordinate is pushed out to 43 mm (estimated), but because the rocker profile is falling away rapidly, the result is a larger base circle radius of 16.4 mm that looks clumsy compared with Figure 2. Therefore the exhaust camshaft centres are set at X = 32, Y = 156 from the bottom face. This reminds me of an important design concept that I questioned some years ago. Why was the traditional ‘Y = 0’ datum for cylinder heads set on the bottom (fire) face? I cannot think of an overriding reason. There is very obvious justification, even for historic designs, not to follow this old convention because the bottom face is often skimmed during servicing and consequently the ‘datum’ plane disappears into space. How do you measure from that?
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Inlet Camshaft centre must lie within hatched area. Inlet Limitation 3.
Exhaust Limitation #2.
FIGURE 1
Inlet Limitation #1. 11.75 mm
29.50 mm
29.50 mm
Inlet Limitation #2. 17.00 mm Arcuate
analysis will be and the more processing time that the computer will use. Thus for a complete and thorough analysis of a component, the computer processing time is enormous, to which the answer is to be selectively less thorough, which is how an experienced analyst earns his keep. The software allows the meshing density to be varied, so an area which the analyst feels to be potentially ‘hot’ can receive a finer mesh than one that he feels is unlikely to have a problem. The beauty of the integrated FEA system is that before the CAD operator leaves work in the evening, he can set up his computer to analyse the latest iteration of his design and the information will be ready on his return the following morning. WIRE VALVE SPRINGS
The obvious alternative is to specify the Y = 0 datum on the top face, with the added justification, in our case, that this will be the plane of the cam bearing centres. It is unlikely to be re-machined because the costs of the associated adjustments will add up to more than a replacement head. Generally speaking, unless you’re dealing with irreplaceable memorabilia, if an overhead camshaft head needs the top face re-facing then it’s scrap. Until recently my next move in the rocker arm design would have been to introduce a colleague whose speciality was calculating stress levels in new designs. Indeed this function was so important that a design office would have nearly as many stress analysts as designers. The process was laborious: a) Draft design #1 sent for first analysis. b) Returned for redesign as required and draft design #2 created. c) #2 sent for second analysis and, hopefully, for approval. d) Returned for any final design tweaking. Only after that could the CAD models be released for manufacture.
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Obviously the potential for major bottle-necks was enormous and these were frequently a frustrating reality, until the designers of the CAD packages integrated FEA into their software. This required CAD
So what is wrong with wire valve springs? The simple answer is ‘surge’, but what is surge? If you like excitement, arm yourself with a rod say Ø15 mm x 300 mm long and a roll of say Ø1.0 mm steel piano wire. If you don’t have a lathe, get a helper (wife?) to rotate the rod about its longitudinal axis while you wrap the wire tightly around it for about 400 close coiled pitches. Add stout protective clothing to your wife and release the wire, taking great care to avoid being scourged as the coil partly unwinds; if you subscribe to being a gentleman, let your wife stand behind you. Otherwise, vice versa. You should now
Until recently, a design office would have nearly as many stress analysts as designers” designers to be educated to make their own stress analyses as they developed their designs, while the role of the analyst became more of a back-up or design quality controller. The problem with analysis is that, like many things, it is not as simple as it might first appear. Put simply, the surface of the component is wrapped in an imaginary net skin and at each tying point of the net’s thread (a ‘node’), the computer calculates the stress. The finer the mesh of the net, the greater the number of nodes that will be analysed, the more thorough the
have a light rate coil spring, Ø40 mm to Ø70 mm and an irate wife muttering about silly b*****s. Wimps can probably buy one (spring that is) ready-made, but that’s less ‘challenging’ and far less fun. Form attachment eyes at each end in line with the C/L and fasten the top end to a rafter or similar. Hang a weight on the bottom end sufficient to extend the coils to a pitch of about 12 mm. Give an upward flick to the bottom coil of the spring and observe a small amplitude wave travelling toward the top of the spring. Now observe that as the wave
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46.00 mm
FIGURE 2 32.00 mm
R14.581 mm 30.00 mm
R14.809 mm
31.532 mm
Exhaust Limitation #1.
1.341 mm Swept radius 26.831 mm
Swept radius. 22.309 mm
156.000 mm
reaches the top, it reflects back towards the bottom, where it reflects back up again, etc., until its amplitude decays to zero. What you have observed is an energy wave in your spring, moving at the natural frequency of the spring and decaying to zero due to ‘hysteresis’ (molecular friction + windage) loss. Next repeat the above, but when the wave has completed its first cycle and is about to reflect upwards, give it another flick of similar force to the first. You have applied your two flicks in time with the natural frequency of the spring and observe that the result is a wave that takes the same time to complete its cycle but has greater amplitude than the earlier single flick. The reactions to your two flicks have added together in intensity. This is an example of a spring resonating (surging) when under the effect of a repeated disturbing force, applied at a frequency equal to the spring’s natural frequency and ‘in phase’ with it. Play with your spring and get a feel for
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‘in phase’ versus ‘out of phase’, i.e. input the second flick when the first wave is at the top of the spring and watch the waves appear to pass through each other as they cross. Allow the wave to decay without inputting a new disturbing force for say six cycles and then give it another flick. You have disturbed the spring ‘at a sixth harmonic’ of its natural frequency. Repeat this and observe how even this intermittent input of flicks can accumulate to serious disturbance of the spring. You may well ask, what does flicking a light rate, home-made spring of low natural frequency have to do with a beautifully made, high rate valve spring being hammered at in excess of 6000g? Well actually everything: they’re just at opposing ends on the ‘cause and effect’ scale and our home-made version reacts slowly enough for us to be able to follow its movements by eye. Once you have observed these basics and understand the terminology, you can begin to study spring vibration theory.
WHY IS SPRING SURGE A PROBLEM? The ‘wave’ is a compressed local section of the spring; therefore the ability of that section to contribute to the spring’s force is reduced. When in severe surge, there may be insufficient force remaining to control the valve train, resulting in ‘float’ whereby the cam profile is no longer in contact with the cam follower, the valve train just tags along behind as best it can and there will be heavy contact when the valve train catches up with the cam profile. There is also potential for valve to piston contact, which will be followed by almost certain engine failure. When resonating, adjacent coils can be compressed until coil clash occurs. This corresponds to a maximum stress condition in the spring wire and while not terminal, is not recommended. Try to view films of valve springs running in surge: springs out of contact with retainers; springs out of contact with seats and in extremis; springs out of contact with both at the same time – alarming. What is less clear to see, either on our home-made spring, or on high-speed film,
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is that associated with our compressed coil (or coils) is an expanded section that can add spring force which can be utilised. ANSWER TO SURGE: AIR SPRINGS Well, not entirely, because like any other elastic system air springs also resonate, but fortunately not seriously at the speeds that we are aiming for. Some years ago, at a time when air springs were not within the capability of our modest development budget, I had managed to design our valve gear to run adequate performance lift curves to in excess of 13,800 rpm with reliability, controlled by steel wire springs. Albeit beautifully-made steel wire springs manufactured by Kauffmann in Germany, but wire springs nonetheless and at a time when every other company supplying F1 engines had been on air springs for, I recall, at least two years. It was time to push air springs closer to the top of our development wish list. Another of Keith Duckworth’s pearls of wisdom was, “Always define your own
thoughts, before investigating the previous work of others.” This ensures that you do not mislead yourself by implanting preconceived notions that may not be truly applicable to your own problem. So keeping it simple, as befits a simple old chap, I thought of an air spring as being an adaptation of a hand-operated bicycle tyre pump and that the main seal would
1.341 mm
blind bore that would not taper smaller near to its blind end? We thought that it would be beyond us and that our only available solution would be a static seal. The downside of a static seal when compared with a moving seal, is that it reduces the piston area for any given cylinder outer diameter (usually limited). So for any required valve closing force,
Always define your own thoughts, before investigating the previous work of others” have to be static, with the piston moving within it. I reasoned that when subjected to the extreme dynamics of valve operation, as noted earlier over 6,000g, a moving seal would lose contact, or worse still tie itself into a knot. Clearly the manufacturing quality for either a static or a moving seal system would need to be of the highest order to minimise air loss. For the moving seal system how could we hone an effectively
higher air pressures are required for a static seal than a moving seal, logically creating a greater danger of leakage. Our static seal system drawings were completed and we looked for partners with the required manufacturing capabilities. In the next article I will look at the concept of air spring design and, if space permits, begin the dynamics of cam profile design. RT
R16.400 mm
R14.581 mm
FIGURE 3
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30.000 mm
43.000 mm
1.982 mm
156.000 mm
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ENGINE TECHNOLOGY THE OIL SYSTEM PART 2
FEELING BAFFLED? John Coxon concludes his guide to oil systems by considering the intricacies of dry sump technology
T
HE DESIGN of a wet sump oil system that can cope with the high g-forces encountered during modern racing is far from easy. Some OE vehicle manufacturers have dynamic tilt table test rigs, where the engine can be run fully loaded and at all manner of angles from horizontal, to replicate oil surge but these are hugely expensive and consequently very rare. For the rest of us, the only true test is on the track itself. Over the years, better tyres and more powerful braking systems, not to mention the extra performance of engines, have made wet sump systems harder to develop to acceptable standards. Indeed, when you look at the range and availability of high quality alternatives, it
ABOVE Mountune’s three-stage LMP2 oil pump
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makes you question why you would want to develop one in the first place. Certainly the debate over the balance between cost and complexity has raged long and hard amongst British Touring Car Championship competitors, with the Super 2000 category battling the tide in its continued use of wet sump systems. Accumulators can have a place, mitigating the worst of oil gallery pressure fluctuations, but to eliminate the effects of oil surge entirely requires a dry sump system. The basic elements of such a system include a pump to supply oil under pressure, a method of extracting the oil from the engine crankcase and a way of removing any air entrained. In addition, the oil will most probably need to be filtered to
RIGHT The British Touring Car Championship remains a champion of wet sumps, carrying over the technology to the Next Generation Touring Car which represents the future of the series (Photo: BTCC)
remove any carbonaceous material or metal debris and cooled to preserve both its viscosity and useful life. An oil which gets too hot in use is more likely to experience thermal degradation or break down under the action of mechanical shear. Using a full flow filter and keeping the oil temperature within the appropriate bounds will therefore not only improve the effectiveness of the oil in the system but also reduce its general degradation in use. As well as eliminating oil surge, engines fitted with dry sumps can be mounted significantly lower in the chassis. This not only reduces lateral weight transfer during cornering but can also have less noticeable but nevertheless beneficial effects on weight transfer during braking and accelerating. A hidden benefit not always appreciated is the likelihood of a small but nonetheless highly useful increase in engine performance. We’ll go into the reasons for this later. At first glance it may look easy to design
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a dry sump oil system: a pump to supply oil to the engine oil gallery; another to ‘suck’ it all out again; and a tank to store it in the meantime. Nothing can be further from the truth.
critical engine performance, too much oil flowing around the engine can interfere with the operation of the systems and cause, for example, hydraulic lock where the oil cannot escape or drain freely. Too
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might look the part; it might even impress your mates (at least those that don’t know better). But I doubt it will be anywhere near as good as one sourced either by the engine manufacturer or from one of the genuine aftermarket oil system suppliers that are now to be found. Before we go into the details of the other components in a dry sump system, let us look at the design requirements of the oil pressure pump for any internal combustion engine.
While not enough oil has dire consequences, supplying too much creates other issues” To start with, the oil pump supplying the engine must provide just enough oil to lubricate all the systems therein: the main and big-end bearings, the cam bearings, the cam lobes and all the other areas where relative sliding of components takes place. This should be sufficient to lubricate everything at a range of engine speeds and loads without supplying too much. While not enough oil has dire consequences, supplying too much creates other issues. As well as sapping all too
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much oil can sometimes cause seals to fail and of course all the oil being pumped into an engine needs to be sucked out at some point, which increases additional nonessential parasitic losses. As a rule engine manufacturers spend a lot of time analysing and designing oil systems and then testing them at a range of operational conditions before approving them for production. If you think that as even a gifted amateur you can specify a better pumping system, then I disagree. It
THE PRESSURE PUMP Last month we looked at a little of the theory but the only way to reliably determine the amount of oil required for an engine is to simply measure it. Certainly flow rates can be calculated using classical bearing theory and the theory of fluid flow through small orifices. But, given the
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inaccuracies of such methods, the best way will be to use some form of turbine flow meter measuring the oil flow as it enters the engine main oil gallery. When it comes down to the design of the pump itself, there are many types but those intended for engine use tend to fall into two basic categories: external gear pumps, where two gears are mounted side by side; and those pumps using a particular form of eccentric operation commonly known as the ‘Gerotor’.
BELOW A simple dry sump arrangement
PUMP CHOICE Gear pumps are perhaps the easiest to understand and were once the most commonly used. They consist of a pair of gear wheels – one driven from the engine, the other meshing with it. When introduced on one side, oil becomes trapped between the gear teeth and the casing and is transferred by the motion of the gears to the other side. Thus for every passing gear tooth a given volume of oil is transferred and the volumetric output of the pump is therefore proportional to the speed of the gear wheels. Using straight cut gear teeth of an involute tooth form, the volume pumped is dependent on the pitch circle diameter of the teeth as well as their width. The greatest output of the pump is realised when for a given diameter the number of teeth is minimised. Although simple in concept and cheap to make, ‘spur-gear’ oil pumps can suffer greatly from cavitation of the oil at high engine speeds. Cavitation is when the pump tries to pull in the oil somewhat faster than the flow dynamics will allow, so gas bubbles are formed and collapse again or implode as the pressure recovers. This causes erosion at those places in the pump where these instantaneous pressure fluctuations ‘pluck’ material out of the surface of the pump. Careful design of the intake port or limiting the speed of the engine can minimise this effect but many manufacturers have now moved over to use Gerotor-style pumps. Although its basic design concept goes back to the beginning of the 19th century, the ‘GeRotor’ principle (derived from GEnerating ROTOR) consists primarily of two elements: an inner and an outer rotor. Designed using a trochoidal inner rotor, from which the outer rotor is developed by intersecting circular arcs, the inner has one
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RIGHT The internals of a Gerotor pump (Photo: Pace Products)
less tooth than the corresponding outer with the centrelines of each a fixed eccentricity to each other. As the two rotors revolve about their respective axes, the chamber volume between them increases and then decreases, which, when linked to crescentshaped ports, produces the required output. Trochoids are developed geometrically by rotating circles around the perimeter of other circles without slipping. They are relatively simple to manufacture by traditional CNC machine tooling but netshaping metal sintering methods are
now increasingly common. Gerotor-style pumps have been around for quite some time but the automotive business didn’t fully appreciate their advantages until the early 1980s. The shape of each of the lobes is such that the surfaces are always in tangent to each other, almost touching the opposing lobe. This keeps an oil seal between the two elements and prevents backwards slippage of the oil as it progresses through the pump. A major advantage to this kind of pump over previous designs is one of packaging and the reduced pressure
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RIGHT Twin lobe pumps may be considered where space is limited (Photo: Auto Verdi)
fluctuations in the delivery port. With engines moving towards crankshafttriggered ignition no longer requiring a distributor, oil pumps running directly from the nose of the crankshaft are more desirable, the flexibility of the design and the reduced costs of manufacture proving very attractive. In most racing engine applications, where the length of the engine is critical, the oil pump is mounted low down, often below the crankshaft centre-line, and is driven off the nose of the crankshaft using a toothed belt or roller chain. In positioning the oil pump the old adage ‘low and slow’ (the latter referring to the pump
Scavenging the oil presents the opportunity to reduce pressure in the crankcase” speed) would always seem to be the rule. So which is better: the gear pump or the gerotor profile? It’s an oft-debated subject. Each has its champions amongst engine manufacturers, but there would seem to be no clear winner. The gear pump is highly dependent upon the accuracy of its manufacture and steel gears working within an aluminium housing will always produce clearance issues. The gerotor, on the other hand, seems to be a bit less sensitive to the accuracy of manufacture and can therefore accommodate variations in temperature without it affecting pumping efficiency too much. Reputed to be more efficient, easier to make, with better packaging possibilities and less susceptible to cavitation (so long
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as the internals are ‘wetted’ with oil), the gerotor is also less likely to lose its priming oil at start up. In the end the decision often comes down to the cost of manufacture, when gear pumps using billet-machined pump bodies come out as some of the most expensive. THE SCAVENGE PUMP If you thought getting the oil into the engine was difficult, getting it out again is altogether a different issue. The pressure behind the supply of oil to the main gallery will cause it to flow. Once inside the crankcase, however, the only true force available is either that of gravity or by applying a slight depression to the sump outlet. Inside the crankcase the oil
will have been churned and sheared such that if it hasn’t broken down physically in any way, it will at least be mixed with a considerable amount of air and crankcase blow-by; its volume will therefore have increased and its ability to flow will be impaired. In a wet sump the oil in the crankcase will drain down the sloping shelf that generally constitutes a large part of the sump area underneath the engine. In doing so the speed of the oil/air mixture draining will be reduced, giving time for the air bubbles within it to coalesce and separate out from the oil. In dry sump applications this doesn’t need to happen, so the oil/air mixture is scavenged out of the sump using a number of scavenge stages, the size and number of which depend upon the engine and its orientation. In the case of a typical OE engine application, with the engine in the same orientation (and the oil from the cylinder head therefore draining through the standard drain passages), a couple of stages picking up the oil from the base of the sump should suffice – one at the front and one towards the rear. Given that the
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volume of the air/oil mixture will most likely be no greater than twice that of the oil originally injected, these two stages should be of a similar size as the pressure pump stage. Should the engine be angled in any way and the oil draining from the front or rear of the cylinder head impaired, then an extra stage extracting directly from the lowest part of the valve cavity might assist. In the case of a vee engine, this could mean scavenging out of both of the cylinder heads. Starting out with equalsized scavenge pumps, the size of each stage should be progressively reduced during development so that the engine is adequately scavenged while consuming the minimum amount of power. If an engine is not being sufficiently scavenged, the oil level in the tank will appear to increase and the engine progressively loses power. In many cases the type of scavenge pump used will be identical to the pressure pump. This will do the job and minimise costs during manufacture. Thus a gear pump pressure stage is often likely to incorporate gear scavenge pumps on the same shaft. And likewise with gerotorbased equipment. Lobe pumps may be considered where space is limited and large amounts of air could be entrained in the oil. A rather special case of a trochoidal rotor, lobe pumps are based on a design similar to that of the Roots-type supercharger, with two or possibly three lobe rotors rotating
together to offer a much increased displacement for the same installed volume. Unlike other forms of trochoidal shapes, the lobes have to be geared together separately. Despite this, large amounts of air/oil mixture can be easily handled at small pressure differences, which makes them ideal for oil scavenge systems. They are, however, relatively difficult to make and highly sensitive to the clearances between lobes. The accuracy with which the gears have to be manufactured (to minimize backlash) means they are not always a popular solution. THE OIL PAN Having completed its task inside the engine, the oil needs to be removed as quickly as possible from the crankcase. This is the function of the oil pan with one or two additional components. Similar to our wet sump engine applications, the engine needs some form of windage tray to separate the oil as far as possible from the effects of the rotating masses. This should be as close as possible to the rotating assembly but not restrict the drainage of the oil. Positioning of the outlet ports in the pan is generally down to the application and how low the engine needs to sit in the chassis. In many instances, a central trough underneath with ports front and rear will work well. But if, for example, the engine
ABOVE The oil pick-ups sit at both ends of a Mitsubishi Evo sump pan (Photo: Pace Products)
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ABOVE Internal baffles are used within the oil tank to prevent surge when cornering (Photo: Pace Products) flywheel is not the limiting factor in crankshaft height, it may be desirable to lower the engine still further in the chassis and offset the oil pick-ups to one side. Whichever way is selected, some form of coarse filter or debris screen might be advisable to prevent any stray wear material from entering our scavenge pump. It is generally not fully appreciated that scavenging the oil out of the engine presents the opportunity to reduce the pressure in the crankcase. As well as reducing the aerodynamic losses caused by the rotation of the crankshaft, the increased pressure difference across the piston can produce marginal increases in engine performance. Figures like 3-6 bhp are often quoted, but these rely on optimal sizing of the scavenge stages. Too much vacuum (in other words, too much scavenge) can draw air in through the oil seals and increase parasitic losses. Bearing issues can also be introduced when the oil is essentially sucked straight out of the clearance and fails to be carried round with the journal. In scavenging oil from around the engine it sometimes helps to ensure that all the chambers are ‘breathing’ correctly. There should be no impediment to the free flow of oil as it drains towards the sump.
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ENGINE TECHNOLOGY
In purpose-designed race engines, individual cylinders (or pairs of cylinders in a V8 engine) are often separated by a wall starting at the top of the crankcase and going all the way down to the oil pan. Incorporating the main bearing housings, this not only increases the rigidity of the crankcase but can reduce aerodynamic losses than might otherwise exist. It also helps the scavenging process when the downwards motion of the piston effectively pushes the oil into the scavenge port. In such applications each cavity will need its own scavenge pump. THE OIL TANK Once the oil/air mixture has been scavenged out of the engine, the two have to be separated before the oil can be reintroduced. Although air entrained into engine oil has a greater viscosity and can therefore in theory support higher bearing loads, as power unit engineers we always prefer to have the lubricant as incompressible as possible and therefore remove as much air out of the oil as we can. The simplest and quickest way to do this is by using some form of centrifuge. In
BELOW An exploded pump assembly from a Duratec Formula Ford
pumped via the oil filter back to the engine main oil gallery. For most effective separation of the air from the oil the tank should be tall and thin, assuming of course that a suitable position in the vehicle can be found to accommodate the height. When it comes to oil hoses connecting components together, it is surely false economy and potentially lethal to use anything other than the best. That means PTFE-lined braided hoses with purposedesigned lightweight ends. In my opinion industrial hose ends using fir tree roots and jubilee clip have no place
When it comes to oil hoses connecting components together, it is surely false economy to use anything other than the best?” some engines a simple centrifugal air/oil separator attached to the scavenge pump assembly may suffice but, when space allows, a cylindrical-shaped oil storage tank is the much preferred alternative. Providing suitable storage for the oil, when scavenged, its oil is pumped to the top of the storage tank, entering it tangentially. This imparts a degree of spin to the motion with the heavier part (the oil) staying to the outside of the tank while the lighter fraction (the air) migrates to the centre. As the oil winds its way down to the bottom of the tank any entrained air finds its way towards the centre and, being lighter, migrates back towards the top where it can be vented out of harm’s way. Internal baffles are used to prevent surge on corners and under braking, the oil being picked up from the bottom of the tank and
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in any form of competition car. That is a view reinforced by witnessing the mishaps that have resulted from people trying to save money. Where possible, hose lengths should be kept short, especially when attached to the intake side of any pump. Long hoses in rally cars where the oil tank is stored in the boot may be unavoidable but when doing so the diameter of the hose will almost certainly have to be increased to account for the pressure losses. In such cases the engine start procedure, especially on cold mornings, may have to be revised to build up main gallery oil pressure before firing, and engine speeds kept low until the oil temperature starts registering on the gauge. This precaution will be particularly important if using some of the heavier SAE
50 or 60 multigrade oils. Hose diameters will depend purely on the application, but for most 1⁄2 inch (-8) and 5⁄8 inch (-10) should suffice with 3⁄4 inch (-12) reserved for when pressure losses become too great. The only place to position the oil filter is in the pressure line to the main engine oil gallery. The location of the oil cooler, however, is up for debate. Some prefer to put it between the pressure pump outlet and the filter; others like to see it in the return line from the scavenge pump to the oil tank. In the case of the former, the cooler will see a smaller volume but at full engine oil pressure; in the case of the latter, pressures will be less with an increased volume as a result of entrained air. So long as the cooler is selected to cope with the flow rate required and temperature drop demanded, either method is entirely satisfactory, although hot oil will always give up its entrained air more easily. The design and development of engine dry sump systems is not an exact science. While the combined experience developed over the years serves as a baseline from which systems can be refined on the engine test bed, the optimum solution can often only be produced after much evaluation on the track. Aftermarket suppliers and engine tuners spend much time developing their products. While it might be tempting to develop a system of your own, this is one area best left to the experts. There are now a number of reputable companies, all willing to offer you advice and equipment to solve your oil surge needs. It makes little sense to ignore them. • The author would like to thank Pace Products of Haverhill, England for assisting with some of the information in this article.
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SPECIAL REPORT BRAKE TECHNOLOGY
BRAKE WITH Chris Pickering reports that a number of companies have ripped up their own rulebook to continue the motorsport brake industry’s pursuit of excellence
A
WHILE back, when the road car industry’s obsession with nought to 60 mph times was at its height, there was an advert that caught everybody’s attention. It only bore the image of a humble family saloon, but above the headline ran ‘60-0 mph in 3.8 seconds!’ This apparently electrifying performance caught the eye of many armchair statisticians until it slowly dawned on them that something was amiss with the order of the numbers. Yet while it might take an element of
trickery to get the marketing people excited about brakes, it does yield some pretty spectacular technology, with some equally dramatic figures. Take Formula One, for example. The current cars can pull nearly 6g in deceleration and it takes around 2,500 hp of braking power to do so. Or, to put it another way, it has a braking power-toweight ratio of 3,900 hp/ton, which suddenly makes the car’s accelerative abilities seem a little tame. Of course, the kinetic energy all has to go somewhere and most of
it leaves as heat; the carbon-carbon discs work at upwards of 750˚C, glowing bright red behind the wheel shrouds. None of this would be possible without a thoroughly engineered system of friction surfaces, hydraulics and immensely strong hardware. And that brings us to the topic of this month’s special report – a cross section of the motorsport braking industry, which starts, appropriately enough, at the very point where a stationary slab of friction material meets a fast rotating brake disc...
Better understanding of how the processing of the material can be used to manipulate its microstructure”
ABOVE With brakes expected to work harder than ever before, the companies in this sector of the market are working harder too (Photo: LAT)
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TRADITION! FERODO RACING At first glance, the job of a brake pad might appear to be pretty simple. Logically you’d assume it’s just a question of providing the highest coefficient of friction you can achieve for a given rate of wear; softer materials tend to grip better, but harder materials tend to last longer. But these days there’s far more to it than that. Recently Ferodo Racing has been looking at not just how rapidly the pad material is worn away, but the specific process that takes place as it’s eroded. The aim is to better understand how the processing of the material can be used to manipulate its microstructure, and, in particular, the porosity of the material. “The porosity is important as it dictates how the decomposition products can escape, but we're also arriving at the conclusion that it's very important to how a driver controls his brake,” explains Ferodo Racing’s Edward Little. “The current tendency in the industry is to create increasingly incompressible bricks to stand up to the demands of the really tough assignments, such as rallying and GT racing.” The trick, he explains, is to make a pad that's tough enough to last, but with the correct porosity to facilitate feel and gas egress, without simply making it soft, which would lead to a long pedal. Ferodo’s answer is the new DSUNO heavy duty racing material, which will replace the old DS2.11 later this year. “The technical objective of the material was to provide a high friction output, while improving pad and disc life, as well as excellent modulability,” Little comments. He explains that these targets have been achieved through a combination of traditional formulation techniques and the use of a 3D silicon polymeric backbone; the latter serves both to bind the other components and provide an abrasive aid. A major feature of the material is its ease of control – as Little puts it: “this is how we define the ‘modulability’ of the pad”. The key to improving it, he claims, lies with the production method: “Rather than being completely constrained in hot press tooling
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Leading GT pad ABOVE & BELOW These graphs show the fade performance of Ferodo’s DSUNO material against two of its leading competitors on a brake dynamometer. It displays remarkably consistent results, with virtually identical behaviour on each application of the pads once they’re up to temperature (from about the ninth stop)
Leading endurance pad
DSUNO
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during processing, which is the industry norm, the material is allowed to find its own natural porosity by pressing and then curing in a much longer and more moderate process.” Instead of being performed during the pressing operation, it’s done afterwards. This, Little explains, helps to give the pad a strong macroscopic (or ‘whole pad’) strength, but also improved microscopic flexibility. The latter is said to improve modulation, which means the risk of locking a wheel is significantly reduced compared to other nominally high-friction pad materials, despite no claimed loss of output.
more worryingly, so can the fluid. If the fluid begins to boil, it can release compressible gasses into the system. From that point on, much of the work done by the master cylinder goes into squeezing the gas, rather than transmitting pressure to the slave cylinders. It leads to the characteristic spongy pedal and a potentially catastrophic loss of braking ability. So, what can you do to stop it? On a basic level you have two choices: either limit the amount of heat being transferred to the brake fluid, which isn’t always practical, or improve the high-temperature performance of the brake fluid. And that’s where
minimum specification that you could receive; it can be the result of a test on a single sample. Typical values for RH665 are invariably higher than 325°C.” A similar situation applies to wet boiling points, he argues (those where a small amount of water has been added to simulate the hygroscopic nature of the fluid): “RH665 is guaranteed to be above 195°C; its typical values are actually much higher.” Boiling point is, of course, not the whole story. With brake fluid it’s also essential to have the correct balance of viscosity, compressibility and lubricating properties. “Low viscosity is very important to ensure a
BELOW The Zero 43 (left) was voted Most Innovative New Motorsport Product. Performance Friction’s RH665 fluid (right) is specially formulated for racing applications
The highest guaranteed minimum dry boiling point of any DOT 4 brake fluid” PERFORMANCE FRICTION The fundamental process of braking is, as any high school physics student will tell you, a matter of turning the kinetic energy into heat. The friction between the discs and pads generates huge quantities of thermal energy (as can be witnessed by the cherry red glow coming from behind the wheels of race and rally cars at night), but the question is: where does it go from there? Ideally, of course, a ready supply of fresh air would keep the friction components at an optimum temperature and there wouldn’t be any heat soak into the rest of the system, but this doesn’t happen in the real world. The brake pads themselves can overheat and, perhaps
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Performance Friction’s RH665 fluid comes in. Specially formulated for racing applications, it uses a complex mixture of glycol ether borate esters and polyalkylene glycol ethers together with advanced corrosion inhibitors, antioxidants and other modifiers. The result, its makers state, is not only a very high boiling point, but also a fluid that conforms to the viscosity standard of FMVSS116 DOT4. Performance Friction claims that RH665 has the highest guaranteed minimum dry boiling point (ERBP) of any DOT 4 brake fluid, at 325°C. And in reality there’s more to this than meets the eye. “Many manufacturers quote ‘typical’ boiling points, which can be misleading,” explains Performance Friction Europe’s Norman Barker. “This is not the
good bleed,” comments Barker. “Similarly, low compressibility is essential for a firm pedal and lubricity is vitally important for efficiency, pedal return and life of the brake system.” And there’s also a materials concern. Part of the American FMVSS, to which RH665 complies, is a series of tests to confirm it’s compatible with all the rubbers (SBR, EPDM etc) and metals which are commonly used in brake systems. Of course, the fluid is only part of the story. Performance Friction has also been developing its calliper technology recently, such as the Zero 43 which scooped our Most Innovative New Motorsport Product award back in January. It features a pad retraction system intended to eliminate the problems
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associated with brake drag. This arises when the pads are allowed to rest in contact with the disc and not only creates resistance to the wheel’s rotation, but also applies additional loads to the suspension. It uses two shoulder bolts, a pressed hip collar and a Belleville spring. When the system actuates, it pulls against the spring in the calliper body, which then presses against the disc. As the pads wear and they, along with the piston, slide towards the disc, the system self-adjusts to avoid any changes to the pedal travel. What’s more, the spring allows you to adjust the amount of movement, and Performance Friction tells us it can be done without losing any pedal travel at all if it’s correctly tuned. The brake timing can also be adjusted. “If a vehicle has a twitch at the rear end under braking, the pad retraction system can be used to delay the actuation of the rear brakes so that the front ones come on first,” Barker explains. “In addition to better grip, it also has the benefit of establishing more equal temperatures front to rear by running more rear bias.” WILWOOD It’s been a busy few months at Wilwood Engineering’s Californian HQ. It’s seen new products come to the market for just about every part of the brake system, stretching from pedal box assemblies by the driver’s feet, to discs and callipers on the hubs themselves. Our look at the recent releases starts at the wheel end, with the new Forged Narrow Mount Dynalite Calliper (or FNDL), which is designed to serve a wide range of applications
LEFT Wilwood’s new Forged Narrow Mount Dynalite Calliper is designed for a wide range of applications
ABOVE The Forward Mount Pedal Assembly positions the master cylinders outside on the firewall
The FDNL features high-temperature seals and stainless steel pistons, in order to resist corrosion and retard heat transfer from the pads. Similarly, each calliper is equipped with Wilwood’s SRS stainless steel bridge plates to reduce pad rattle and dampen the vibration harmonics that contribute to squeal under braking. On a more practical level, it also comes with four corner bleed screws, which are designed to help air evacuation when the brakes are bled. Moving up the hydraulic system, we reach
Stress-flow forging to realign the metal’s grain structure within the contours of the calliper body”
two outlets. This means it can be run as a single outlet with one outlet plugged, or can be used to split the plumbing on its way to the front callipers. Last, but by no means least, comes the company’s new pedal assemblies. Available either in adjustable reverse mounting or forward mounting configurations, they combine the brake and clutch pedal assemblies together in one unit. The Reverse Mount Pedal Assembly positions the master cylinders inside of the firewall, while the Forward Mount Pedal Assembly positions the master cylinders outside on the firewall. Both units feature an all-aluminium frame and forged aluminium pedal arms with ladder-style construction. The frame and pedal arms are Platinum-E coated for protection and aesthetics, while the pedal pads themselves are of a special adjustable lightweight design that allows fine-tuning of the pedal location and clearance. Also included with the assembly is a choice of mounting studs and hardware, as well as a clevis and pivot pin balance bar that’s designed to provide smooth and accurate settings of the brake pedal bias. This can be set and locked down with a lock nut, or attached to a remote cable for quick on-track adjustments. The end result is a ratio of up to 6.25 to 1 on both the clutch and brake pedal. AP RACING
including circle track racing, sprints, off-road and road racing. It’s a direct replacement for the company’s older NDL designs and is said to be compatible with other brands designed for 3.5-inch centred mounting tabs. It was developed using finite element analysis and features stress-flow forging that realigns the metal’s grain structure within the contours of the calliper body. As a result, the company claims it’s one of the strongest calliper designs on the market.
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Wilwood’s new Combination Proportioning Valve. It’s been designed to provide a straightforward brake proportioning adjustment on cars with bespoke brake systems. It maintains full isolation between front and rear fluid circuits, and it can be used in conjunction with any tandem outlet or dual mount master cylinder assemblies. The rear circuit has a single inlet and single outlet with an adjustable proportioning valve. The front circuit has a single inlet with
When AP Racing’s Radi-Cal range first appeared in 2007 it represented a truly clean sheet approach to brake calliper design. Rather than building on conventional wisdom, the engineers questioned whether callipers really should resemble the pattern they had evolved into. It came at a time when the emphasis placed on cooling was rising dramatically, and it prompted a fairly radical redesign. The engineers began – somewhat
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LEFT & BELOW The new GT racing rear calliper variant of AP Racing’s Radi-Cal range (left); the rally raid version (below) is designed to reduce brake calliper temperatures in extreme environments surprisingly – by stretching a CAD model of a calliper out in all directions to make the most of the space available. This made for a strong and dynamically stiff calliper, but it clearly wasn’t a practical solution, so next they used an extensive FEA study to identify the areas which could be pared away to save weight and improve cooling, without compromising strength. The use of 3D computer modelling for development, allied to improvements in 5axis machining for production, meant that designs which wouldn’t have been possible previously were suddenly viable. By making cooling a priority the company claims it not only improved the performance of the callipers, but also their durability and – indirectly – their weight. The result of the first Radi-Cal projects wasn’t a specific geometry, but rather a design concept that’s since been rolled out to the rest of the range. And the big news at AP currently is of new additions, intended for GT, Rally Raid and Super 2000 rally applications. The new GT racing rear calliper, the CP6470, is intended to complement the existing Radi-Cal designs for the front end. It’s designed to be used with either carbon/carbon or ventilated iron discs of 355 mm diameter, and comes internally ported, with titanium pistons and dry break couplings fitted as standard. The rally raid variant (numbered CP6768 for both front and rear applications) is designed specifically to reduce brake calliper
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Engineers questioned whether callipers really should resemble the pattern they had evolved into” temperatures in extreme environments. It uses a specially developed cooling duct to channel air into the calliper, as well as a recirculating liquid cooling system, and there’s also a port for a temperature sensor probe. Similarly, high temperature, low-drag seals are fitted as standard and special attention has been paid to sealing the units from dirt and water ingress. Finally, the CP6830 (front) and CP6831
(rear) rally callipers continue the range for both tarmac and gravel rallying. They’re suitable for all Super 2000 rally applications and they’ve recently found a starring role on the works’ Mini Countryman WRC, which is due to make its debut on the Rally Sardinia this May. They feature a 4-piston layout designed to work with ventilated iron discs and equipped with a similar ducted air cooling channel to the rally raid design.
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STOPTECH California-based StopTech has made a name for itself producing brake upgrade systems for production-based race cars with OEbased systems. It uses a flexible manufacturing process that allows it to create a wide range of geometries, rotor widths and piston area from just a few basic callipers. Having supplied race-winning systems for touring cars and GTs, the company is now expanding its manufacturing capabilities to support faster development cycles for race, speciality, military and OEM projects. “We have always supplied rotors of the highest quality, and that has served our customers well,” states Steve Ruiz, StopTech’s director of engineering. “But we have faced challenges with production lead times and tooling costs for new numbers from vendors that could deliver the right parts.” As a result, StopTech has moved production of racing rotors to the US, setting up a rotor machining and balancing line at its Southern California manufacturing facility. The company says production has already started and will be expanded over the coming year to support custom, twopiece rotors from small to very large, in a
range of thicknesses and air gaps, able to support any drive hardware. “We will stock raw castings from a proven domestic foundry partner,” says Ruiz. “This cuts the time for a new part number to be tested on one of our Link dynos or the racetrack from many months to just a few weeks. All the castings will incorporate our patented AeroRotor vane technology, as well as conform to our proprietary metallurgical requirements, maximizing cooling and durability.”
and 400+ horsepower. And now StopTech has gone in the opposite direction, kicking off the new STR42 calliper for lightweight categories, as Ryan Kim, Motorsports Sales Engineer, explains: “The STR-42 embeds the same race-winning paradigms of low mass, stiffness and application flexibility found throughout our calliper line in a package perfect for off-road, rally, circle track, formula cars and production-based sports and compact cars.”
Cutting the time for a new part number from many months to just a few weeks” The company has also recently invested in a Mori Seki NMV5000DCG five-axis mill with pallet pool, fast-forwarding the expansion of its calliper range with billet components for specialized markets. At the PRI show in December, Race Tech saw StopTech’s new STR-40 GT calliper, engineered around the rulebooks for the higher classes of production-based endurance racing, with cars over 3000 lb
“As our customer base grows, it becomes clear that specialized markets require more specific products,” says Mark Cornwell, VP of Sales and Marketing. “The volume doesn’t always justify the expense of production tooling, and many programmes can’t afford that delay. Our latest investments empower us to deliver enhanced, customer-focused solutions without limitation on the timeline required in a competition environment.” RT
BELOW StopTech’s new STR-42 calliper serves rotors 313 mm and smaller, in widths from 5 mm to 32 mm. Piston sizes from less than 30 mm to 40 mm are possible, and may include the company’s low-thermal-transfer technology. It is internally ported for durability in rally and off-road service
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PRACTICAL RACER 750FORMULA BUILD PART 11
THE SHOW’S OVER… Graham Templeman and Rod Hill set to work designing the brake system for their 750Formula racecar AFTER THE glamour of the show comes the graft of getting the car finished. There are now dozens of major items and hundreds of lesser things to be made, bought or found somehow. There are two wives hovering in the background wondering how much this is all going to cost and, at the moment, falling for the propaganda that there are lots of minor, pocket-money items to be bought and although there will be some big hits to be suffered, these will come somewhat further down the line when we have had time to raise the money. The plan is to start with fitting the various systems into the chassis before it gets its riveted side and floor panels and the bodywork. The body moulds and pieces will be started as soon as we get some input from Oxford Brookes and the engine and its support systems will be last major phase in the construction process. There will then follow more time than you would expect in simply getting everything painted, assembled and connected. We decided to start by making and fitting the pedals and designing the braking system which will be one of the big financial outlays referred to earlier. That then brought with it the realisation that we really need a seat so that we can be sure that any driver can reach all the controls and can see the instruments, and enough of the corners of the car to make close racing safe. This makes the manufacture of a mould and a seat the next job. But brakes first. Experience with lots of club racers and plenty of real data is that few amateur drivers achieve anything like the maximum potential under braking. I believe that this is partly due to technique, partly to not having the balance set
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ABOVE Actually making the brake pedal was relatively straightforward compared to calculating its dimensions
correctly and partly because some systems are just not powerful enough. Technique can be cured by taking a driver through the data and showing him or her that braking levels are just not good enough. In any set of data, there is likely to be one or two really good braking events. If it can be managed once in the 40 or 50
he or she will almost certainly develop a feel for the balance. Only then should they be entrusted with a cockpit-adjustable brake balance. Making sure that the system has sufficient power is a two-part process. Part one looks at how much grip the tyres can provide; part two, at the equipment needed to make
Few amateur drivers achieve anything like the maximum potential under braking” braking attempts in a 10-lap race, it should be managed every time. This is a way of finding lap time really cheaply. Use what you have to the best of its potential. Getting the balance right is partly a design issue and partly a skill that the driver learns. Once the balance is about right and the driver is really applying the brakes properly,
sure that all of the available grip is used. The tyres provide grip according to their coefficient of friction and the weight acting on them. Data logging will point us in the direction of the coefficient of friction – proper tyre data is only available at the highest professional levels and FSAE. Because our 750Formula tyres will generate
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PRACTICAL RACER 71
BELOW A traditional balance bar mechanism. The ‘make or buy?’ decision was an easy one
WEIGHT TRANSFER Front kg
Rear kg
Front%
Rear %
Before the brakes are applied
200
250
44.4
55.6
After the brakes are applied
200+100
250-100
66.7
33.3
Before the brakes are applied
200+95
250+95
46.1
53.9
After the brakes are applied
200+100+95
250-100+95
61.7
38.3
Axle loads without downforce
Axle loads with downforce
about 1.8g cornering, we need to design for something like that under braking. We are unlikely to achieve this repeatedly, 1.4 being nearer the mark, but it shows us the range in which we should be operating. Using 1.5 in the design calculations for the brakes of a Sports 2000 on the same tyres gave braking which a driver with current LMP experience described as “awesome”. The target weight is 450 kg (990 lb) all up, split 200 kg front, 250 kg rear. This might be greater or smaller, depending on the success of the driver's diet. The wheelbase is 2,125 mm (84 in) and centre of gravity is guessed at 305 mm (12 in). This is all the data that we need to calculate weight transfer. At our target of 1.5g, the weight transferred from the rear to the front axle is:
(Weight x Braking force) x (
CG Height Wheelbase
)
So 450 kg x 1.5g gives an effective weight of 675 kg and of this, 305 ÷ 2125 (14.8%) is transferred from the back wheels to the front. 14.8% of 675 kg amounts to 100 kg taken from the back wheels and transferred forward. So the axle loads under braking become: Front Rear
200 + 100 = 300 250 - 100 = 150
These calculations are the same if you use pounds and inches but be careful to express the distances in identical units. With this information, we know how much braking effort is needed at the tyre contact patch. Managing this weight transfer is one of
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the key skills that a driver must master. The balance is set up to maximise braking with the weight transferred, but the transfer has to be initiated when the loads are quite different. The driver is faced with the conundrum of getting the weight onto the front wheels without loss of grip at either end. There is the added consideration of downforce. Our aspirations are fairly modest in this respect: we have a target of
about 100 kg at each end of the car. This will not be subject to weight transfer but will bleed away as the speed decreases, meaning that the loads will vary according to speed. Under braking, the force on the front axle will be between 300 and 395 and between 150 and 250 at the rear depending on speed. The table shows the range of conditions that the driver has to cope with but is based on 95 kg of downforce to make the numbers clearer. The table quantifies the driver's problem. By the time the brakes are fully applied, the balance shifts from the static 45/55 to the dynamic 62/38. Happily, our limited downforce makes little difference to the figures. When downforce is not split evenly between the two axles, it causes the balance to change during braking but bearing in mind that a safe car is one where the aero balance is set slightly rearwards (to give stability in high speed corners) this is less significant than you might imagine. In fact, the effect of downforce is to ‘damp out’ the change in balance between the braked and unbraked conditions. Brake balance can change during braking but this is due to the mechanics of the system rather than the aero load. We have plans to revisit this issue when we reach the testing stage. Now that we have some idea of the dynamic loads on the axle, we can begin to evaluate how much grip is available. This can be calculated by multiplying the axle load by the coefficient of friction of the tyres. From the data and our target we are aiming for 1.5g, so without downforce, the calculation is 300 kg x 1.5 which indicates that the front axle can handle 450 kg of braking effort. This would be increased by the downforce which varies according to
March 2011
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PRACTICAL RACER 750FORMULA BUILD PART 11 BELOW The mechanical advantage built into the brake pedal is the pedal length x balance bar height the square of the speed. If 100 kg is available at 100 mph, there will be 64 kg at 80 mph and 36 kg at 60. So at 100 mph, the 100 kg of downforce, multiplied by the coefficient of friction of 1.5, contributes an additional 150 kg of grip at the front axle. This complicates the issue because in theory much bigger brakes are required at high speed and are redundant everywhere else in the speed range. We need to balance the weight penalty of big brakes against performance in possibly the most important braking zone on every lap. Most circuits have one big brake from high speed, and you wouldn't want to be disadvantaged, would you? Before making that decision we need to look at how much stopping power the brakes can provide. Sadly, this involves some more calculations. The braking system is a simple mechanical/hydraulic system that lends itself to straightforward analysis. We have the benefit of leverage (the pedal and the balance bar to the master cylinder) and some hydraulic ‘leverage’ (ratios between the master cylinders and the callipers). There are a couple of coefficients of friction (brake pad to disc and tyre to road) and leverages again where the pad exerts a torque on the tyre. LEVERAGE RATIO So starting from the pedal, let's expect our driver to exert about 50 kg (110 lb) of force at the pedal. Every pedal has its own leverage ratio (Pedal length ÷ Balance bar height on the diagram) that increases the pedal force exerted on the master cylinder. If the pedal length were 200 mm and the balance bar height 50 mm, this would give a leverage ratio of 4:1 so the master cylinder would see four times the 50 kg that the driver’s leg provided. We start from the assumption that this 200 kg is split 50/50 by the balance bar because we want to design to start in the middle and allow fine tuning in either direction. So each master cylinder sees about 100 kg (220 lb) force on the piston. We then get the benefit of a substantial hydraulic advantage (leverage) because the force generated over a small piston area at the master cylinder is available over a much larger piston area at the calliper. The ratio will be: (Calliper Piston Size ÷ Master Cylinder Diameter)2 x Number of Pistons
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By the time the brakes are fully applied, the balance shifts from the static 45/55 to the dynamic 62/38” So if the master cylinder size is 19 mm (0.75 in) and the four-pot callipers have 38 mm (1.5 in) pistons, the calculation becomes 38 ÷ 19 = 2; squaring this gives 4 and multiplying by four pistons leaves us with a factor of 16. (Note that this calculation only works if all the pistons are the same size – if not it is safest to work out the hydraulic advantage by comparing the total piston areas of calliper and master cylinder.) So the 100 kg (220 lb) of force multiplied by the factor of 16 for the hydraulic advantage becomes 1,600 kg
(3,520 lb) acting on the two brake pads. The 1,600 kg force works through a coefficient of friction of (say) 0.5 so that there is a force of 800 kg acting on the disc. We can convert this into a torque by taking into account the effective radius of the disc. With a diameter of 250 mm (10 in) and a pad with a 50 mm (2 in) height, then the effective radius of the disc is 100 mm and the torque is 800 x 0.1 (metres) or 80 kg/m. In inches and pounds, the 3,520 lb of force at the pistons would generate 1,760 lb of force on the disc,
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RACE TECH magazine is the only independent, technology led motorsport magazine that focuses on every aspect of racing car engineering. Totally international in its outlook, it covers everything that can be found competing on the track from Formula One to the Clubman’s single-seaters, from NASCAR to the Silver Crown cars and from sports racing cars to the weekend hillclimb specials. Topics covered include Engine Components, Aerodynamics, Brake Technology, CADCAM, CFD and simulation software, Coatings, Composites, Connectors, Cooling Systems, Control Systems, Data Acquisition, Drivetrain, Chassis and Transmission Dynos, Electronics, Fabrication, Fluid Systems, Gauges and Instrument Panels, Ignition Systems, Lubricants, Machine Tools, Materials, Powertrain, Radiators, Safety Equipment, Simulation, Suspension Systems, Testing, Track equipment, Transmissions, Tyres, Water Pumps and Wind Tunnels. If you want to reach those parts of the industry that no other publication can, then look no further than RACE TECH.
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PRACTICAL RACER 750FORMULA BUILD PART 11
and, with an effective disc radius of 4 inches, the torque will be 1,760 x 0.333 ft = 587 lb/ft of torque. So one wheel is subject to a braking torque of 80 kg/m that is applied to the wheel through its effective radius of 305 mm and it will generate a force at the tyre contact patch of 80 ÷ 0.305 = 262 kg. That would be 587 lb/ft ÷ 1 ft = 587 lb in the other units. This is the force that we can generate at one contact patch so the pair of front wheels will generate 524 kg of braking effort. Going back to our early calculations, we decided that the front axle could cope with 550 kg in total, so as things stand, the front axle needs more braking potential. There are various things that we could do at this point. We could look again at the sizes we have chosen for the discs, callipers and master cylinder and increase them slightly. We could recognise that at 50 kg of braking effort the wheels will not lock, so the driver can be advised to put in more pedal effort for high speed braking. Or we could simply settle for these figures and know that although we don’t quite have optimal braking at high speeds, nor
do we need to carry, accelerate and brake extra weight. It’s called ‘design compromise’ and life is full of them. Now the whole process needs repeating for the rear brakes. It’s tedious, but using this logic to create a spreadsheet will provide hours of fun playing with the combinations. What the calculations or the what-if’s with a spreadsheet show you is that increasing disc or wheel diameter improves braking in direct proportion to the increase in size. The same goes for the pads' coefficient of friction and this is a major determinant of braking effectiveness. Racing pads traditionally gave about 0.35 but some manufacturers of the latest generation of pads are claiming up to 0.6 using carbon-based compounds. BEWARE MASTER CYLINDER DIAMETER Calliper size is also important but beware of master cylinder diameter. It is beguilingly easy to decrease the size of the master cylinder to improve the hydraulic advantage. This increases the line pressure and there is a limit to this (about 70 bar or 1,000 psi) before callipers begin to feel the
strain. The real problem with specifying a smaller master cylinder is that the piston needs to travel further. Whilst plenty of pedal travel feels reassuring in a road car, a real racing driver likes the pedal rock hard so that the feedback is from the amount of leg effort rather than the distance travelled by the pedal. A similar warning applies to the pedal leverage ratio. Although it is easy to increase the efficiency of the brakes by increasing the leverage, the extra pedal travel is equally undesirable. In any case the ratio is fairly well fixed when the car is built because it is difficult to change the vertical distance between the pedal pivot and the centre of the master cylinders and therefore the balance bar height. All this is a lot of work just to determine the dimensions of the pedal. Actually making the device was fairly straightforward. The body of the pedal was made from 40 mm x 20 mm (1.5 in by 0.75 in) steel tube with a wedge cut out to narrow the stem of the pedal towards the top and two cross tubes were brazed into place. The bottom was 25 mm (one inch) long and with the
ABOVE Detailed set up of the balance bar can wait for now
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PRACTICAL RACER 75
ABOVE The effective radius of the disc is the distance between the wheel centre and the centre of the friction material on the pad same diameter. There was a 16 mm diameter hole bored through this which carries an aluminium bush for the pivot bolt. It would have been a nylon bush, but Rod has had bad experiences of these in the past. The balance bar mechanism was bought from Rally Design for a paltry sum when compared with the effort involved in making the bar, two clevises and the yokes
moving vertically rather than causing the balance bar to move horizontally as its maker intended. It is this vertical movement that people in the know believe to be responsible for variations in balance as the pedal is pushed. If you don't believe me, look carefully at AP’s top of the range pedal boxes and consider that this design was the result of much careful research. Our kit came with a 40 mm tube ready to weld into the pedal to house the bearing. This is an obvious chance for distortion to spoil things, so rather than welding, the tube was brazed in very carefully. Despite these precautions the tube did pull slightly out of round and had to be honed back into shape so that the bearing was a nice smooth sliding fit. One modification was to make a small collar to replace one of the two circlips that retained the spherical joint. This can be
Increasing disc or wheel diameter improves braking in direct proportion to the increase in size� that the pushrods fit into. We are all for building as much of the car as possible, but this make or buy decision was easy. As bought, the spherical bearing is quite loose, but we regard this as a plus point because using a top quality bearing here introduces stiction that can result in the pushrods taking the easy way out and
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secured with a grub screw and allows us to take out a small amount of end float. Setting up the balance bar is one of the jobs that will be necessary as the project approaches completion, but at the moment all that has been done is to make sure that the two yokes are 41 mm apart. This will give 1 mm (040 in) end-float to the bar, big enough to avoid binding up in operation, but also small enough to limit the travel of the bar in the event of one circuit failing to operate. When the time comes to do the detailed set up, we will need to know the distance between the clevises and the distance between one clevis and the centre of the spherical bearing (dimension A in the diagram). The target will be to make this dimension exactly half the distance between the clevises to give a 50/50 balance. Shortening the dimension will put more effort into the master cylinder on that side of the pedal. If we have done the sums right, once set up, we should not expect to have to move the bearing much more than 4 or 5 mm to get the precise balance that we want. Time will tell. RT
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RED RACE EQUIPMENT DIGEST
Edited by Chris Pickering
ACO-COMPLIANT SCRUTINEERING LOOMS OUR FIRST product this week comes from DC Electronics. It’s a response to the new ACO ruling that all cars running in its various championships must carry a dedicated scrutineering data logger. While the loggers and the sensors are mandated components supplied together, the kit does not include any sort of wiring to connect them together. And that’s where DC Electronics comes in. The task of manufacturing a professional-quality wiring harness for endurance racing is actually a surprisingly involved one. Highly specialist connectors require highly specialised, not to mention rather expensive, tools as DC Electronics
managing director David Cunliffe explains: “Because every car is different you basically just get a box of bits and a wiring diagram in the scrutineering logger kits, and many teams simply don’t have the resources to produce a loom for them in-house. The specialist crimp tools and dies required to fit Autosport connectors aren’t the sort of thing you find in the average toolkit, which is where a specialist wiring house can help.” The production was originally triggered by a request from a US customer running a 911 GT3, and DC Electronics has since adapted the design to serve as template for other applications. Because the basic
ABOVE Flying Lizard Motorsports will use the new loom in the American Le Mans Series
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architecture is constrained by the ACO rules, all that’s fundamentally required to produce different variants is a new set of wire lengths. To this end, the company has released a schematic of the loom on its website for teams to measure the required cable lengths and request a custom loom. “Essentially the teams just have to decide where they’re going to mount the logger box and the various sensors, then just fill in the dimensions and send it back to us,” continues Cunliffe. “We then build the loom using lightweight military-spec Raychem System 25 materials, test it on a Sirus test bench and supply it as a completed ‘plug and play’ installation.” The scrutineering loom remains completely separate to the vehicle’s own electrical system, meaning it can be removed and refitted very easily if the team intends to contest non-ACO events. Plus, as well as the conventional pattern, there is also a version available to suit the ACO hybrid regulations for the Le Mans 24 Hour Race, the Le Mans Race Series, the American Le Mans Series and the Inter-Continental Le Mans Cup. RT
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NEW DIRECTIONS IN RACE CAR AERODYNAMICS Designing for Speed By Joseph Katz Published by Bentley Publishers ÂŁ23.95
+ Post and Packing
Well versed in the subject of aerodynamics as the Department Chair, Aerospace Engineering and Engineering Mechanics at San Diego Univserity, Dr Joseph Katz does an excellent job of giving a layman's introduction to auto-aerodynamics.
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RED RACE EQUIPMENT DIGEST
HOSETECHNIK PERFORMANCE BRAKE HOSES FORGE MOTORSPORT has recently expanded its Hosetechnik range of competition brake lines. It now covers a faintly bewildering 7,000 different fitments for classic and contemporary cars and motorcycles. The company says the right brake hoses can improve pedal feel and braking efficiency by providing an optimum rate of fluid transfer from pedal to pad. The Hosetechnik range uses teflonlined hoses made from braided stainless steel with custom-machined stainless end fittings. Each set is custom made using a unique manufacturing process, which is both DOT and TUV approved. All feature a hard-wearing 95PVC sleeve, designed to protect against dirt and water ingress and available in no less than 12 different colours.
RT
PLAYING IT COOL COATINGS specialist Zircotec is to offer a new derivative of its heat-resistant ceramic composite coating for engineers looking to maintain the airflow speeds of exhaust gases. The latest version of the firm’s ThermoHold for Composites coating has a smooth surface finish designed to minimise
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exhaust gas air flow disruption. It’s hoped that the use of smooth coatings will help Formula One teams to optimise their blown exhaust designs and enable them to recover the downforce lost following the ban on double diffusers. Use of Zircotec’s standard heat-resistant
coatings last year was said to reduce surface temperatures by up to 125°C – potentially enough to prevent the composite substrates underneath from delaminating. It’s said the new coating will provide the same level of heat protection with significantly lower surface drag. That’s not all to come out of Oxfordshire company recently, either. It’s also expanded its ZircoFlex range of thermal barrier foils, which is now available in two and three layer versions, with and without self adhesive backing. There’s also a greater range of sizes on offer, starting at just A4. The company claims the single layer variant can reduce surface temperatures by 64 percent, with reductions of 77 percent and 85 percent said to be achievable for the new double and triple layer foils. Despite this, ZircoFlex remains comparatively light at just 0.46kg/m2 for a 0.25mm thick sheet. RT
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F1 TECHNOLOGY RECEIVES A WORKOUT AND NOW for something slightly different. The Gatherer Partnership’s GP Analysis Suite is a radical new approach to driver fitness training. On a basic level, it uses a load cell to measure the forces which are being applied to the driver’s head via a specially designed harness. The loads can either be generated by the drivers themselves – pulling against a stationary mounting point or a set of weights – or by an assistant physically pulling on the other end of the load cell link. It uses Formula One measurement technology to provide accurate and objective musculoskeletal data and analysis, which can then be used by a doctor or team physiotherapist to asses and condition injuries. The loadcell measures up to 200kg under tension and 100kg under compression with 0.1kg
80
resolution, and a bespoke software interface is used for instant display and analysis of the data. It also means the suite can be used as a training aid. The software graphically displays how much force the drivers are applying at any given time – the greater the force, the further up the graph it’s plotted. This allows them to follow a
moving trace of force against time, which can be used to build up an interval training programme – not unlike ‘virtual’ hills on an exercise bike. More specifically, it can also be used to recreate the realtime forces applied to the drivers’ necks while driving around a particular circuit, such as the long high-g corners of Interlagos or Istanbul. The system was developed by research physiotherapist Don Gatherer, and is currently used by several Formula One drivers including Mark Webber. It was also used by Formula Two champion Dean Stoneman to train and prepare his neck for his recent F1 test, as well as numerous athletes in other disciplines. The photo here, for example, shows Irish international rugby player Rory Best training to recover from a recent injury. RT
POWERHOUSE PRODUCTS
REVERIE CARBON PLENUMS
NEXT UP is a range of tools from US manufacturer Powerhouse Products that begins with a new line of mechanic’s gloves and sleeves. Made from 100 percent ballistic Kevlar, they’re designed to protect the wearer’s hands and arms from heat, cuts and abrasions without sacrificing dexterity. On a somewhat different note, comes the company’s Pro Head CC Kits, designed to simplify the task of physically measuring the volume of components such as combustion chambers, intake and exhaust runners, plenum chambers and cylinders. They’re available in 50cc, 100cc, 125cc and 250cc versions and feature a simple scale system to capture the amount of liquid dispensed by the kit. They feature precision glass burettes, compatible with alcohol, parts washer fluid or virtually any other liquid, along with a stand and clamp assembly, and a flat Plexiglas plate to cover the combustion chamber. Finally, we have the Powerhouse Deluxe Universal Overhead Valve Spring Compressor, which is – perhaps unsurprisingly – a valve spring compressor. It features a removable handle that allows for use with a 5/8” socket or wrench in confined areas and an extra-long leg for versatility. The company recommends using it in conjunction with its 14/18mm Air Operated Valve Holder, which can be used to pressurise the cylinder and keep the valves in place during removal of the springs and keepers. RT
CARBON fibre specialist Reverie has been busy extending its Zolder range of plenum chambers. The deep 112PD and the shallow-backed 65PC variants are both suitable for naturally aspirated engines or turbo applications up to 3 bar boost and designed to fit Reverie carbon fibre backplates (sold separately). They come fitted with an Active Technologies alloy S2000 throttle adapter with a 98.9mm square flange, a 63.7mm bore and 4 by 85mm pcd. Both left and right-handed versions are available. RT
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RED RACE EQUIPMENT DIGEST
HOLLEY SELF-TUNING EFI SYSTEMS MENTION the name Holley, and carburettors are perhaps what first spring to mind, but recently the company’s EFI division has released entire range of fuel injection systems. It begins with Avenger system, which comes as a ‘bolt-on-and-go’ package, designed to be a direct replacement for carburettors and capable of feeding up to 600 hp. A hand-held controller eliminates the need for a laptop, and a self-tuning mode allows the ECU to automatically populate its fuelling and ignition maps. The HP system that follows builds on this with fully programmable mapping, plus additional installation options to suit
generic multipoint systems and GM’s LS ‘plug and play’ engines. It also comes with four configurable inputs and outputs, which can be used for functions like boost control, nitrous control or water/meth injection. On top of that, the HP features internal data-logging, distributorless ignition control, as well as individual cylinder fuel & spark control. Completing the line up is the Dominator system. This, once again, carries over all the features of the model beneath it, along with the addition of electronic transmission control, drive by wire throttle body control and rev limiters, as well as significantly RT more input and output channels.
NEW SEQUENTIAL GEARBOX FOR RACING 911S QUAIFE is soon to launch a new sequential gearbox for the motorsport versions of the Porsche 911, known as the QBE85G. It features an integrated bellhousing designed to suit the 996 and 997 models, a new oil pump design which delivers its lubrication via the gearbox shafts and an oil pressure feed to the pinion intended to ensure stable temperatures for endurance racing. There will be the option of semiautomatic paddleshift conversion, which is even compatible with the standard Porsche sequential gear lever. The new 'box promises to be significantly lighter than the QBE61GP it replaces, and Quaife also says that affordability will be high on the agenda. Already tested in other endurance racing applications, the unit is rated to power outputs of over 450 bhp and comes supplied as a direct RT replacement for the standard Porsche Motorsport transmission.
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www.racetechmag.com
March 2011
A SPARK OF INSPIRATION OKADA Projects recently unveiled its new Plasma Direct ignition coil. The units come with a built-in high-power ignition amplifier, which its makers claim can produce four times more spark energy than stock coils, and generate an ultra-fast multi-spark-discharge of 10 sparks up to highest RPM. Okada claims the spark amperage is increased by 100 percent, helping to accelerate the ignition and combustion processes. This, the company says, is particularly useful in forced induction applications, but also improves the performance of normally aspirated engines. The coils are pitched at the track day and clubman's market; they're intended to be used as a direct replacement for the stock items, with no splicing or cutting into stock wiring. The Okada design is even OBD II compliant, to retain stock diagnostic capabilities. RT
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