Evolve Stage 2 Supercharger BMW E39 M5

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EVOLVE STAGE 2 SUPERCHARGER KIT FOR THE E39 M5 We road-test Evolve Automotive’s Stage 2 supercharger kit for the E39 M5 to see if it delivers the performance we hope it will…

Words: Andy Basoo Photos: Stephen Hall

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Unlike a number of supercharger kits for the E39 M5, Evolve’s mounts the ’charger up top behind the nearside headlight

THE ISSUE t launch, the E39 M5 received rave reviews. It was the best rendition of the model to date.

The primary reason for the high praise is the S62B50 engine under the bonnet. The 4.9-litre V8 was an evolution of the 4.4-litre M62B44 (as found in the 540i) and produced 394bhp. BMW listed a 0-62mph time of 5.3 seconds, but a number of publications found that 62mph came up a few tenths quicker in their independent tests.

It was, and still is, a special engine. But is it perfect? No. The S62 produces its torque very early on, hence its phenomenal pace.

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However, past 5000rpm, despite the V8 being happy to keep revving for another 2k, torque starts to drop off quite quickly. The facts and figures prove the M5 isn’t so much lacking in performance, but from the dyno graph (p89) you can see there’s plenty of room for improvement higher up the rev range.

Production of the E39 M5 didn’t start properly until late 1998. That essentially means that tuning specialists have had the best part of 14 years to find the optimum method of extracting more top-end power from the S62. Countless different naturally aspirated and force induced setups have

been trialled and released, and all have had to adhere to the tight space restrictions under the E39’s bonnet. This in turn has brought with it flaws in many of the solutions that have come to the market.

Raise the bonnet and remove the front bumper from the 5 Series, and you’ll notice that there’s very little in the way of structural support so if you start cutting into or removing sections to fit components, integral strength is very quickly compromised. Finding extra power safely on an E39 M5 then, is perhaps more challenging than on other models.

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Evolve free-flowing headers are recommended but not included

EVOLVE AUTOMOTIVE’S SOLUTION Evolve’s approach to tuning is one that we’ve always respected and appreciated.

Where many companies seek all-out performance and top-end, attention-grabbing power figures, Evolve usually focuses its attention on how the power is achieved and delivered. It’s an ethos that reminds us of one of those motivational posters: ‘It’s not the destination itself but how you get there that’s important’. It’s this line of thinking that Evolve’s always taken with its highlyregarded remaps and ECU tuning, and it’s this same direction it’s taken with its latest offering for the E39. This Stage 2 supercharger kit has been developed to significantly enhance the S62’s performance in all the right places. Great care was taken, though, not to lose the qualities that make the third generation M5 so highly esteemed.

The setup revolves around the Rotrex C3891 ’charger. It’s the latest and highest-spec centrifugal unit in the Rotrex line-up, and as such is used by Porsche tuning house RUF, and supercar manufacturer Koenigsegg. It’s suitable for engines ranging from 3.0-litres to 6.0-litres and possesses three key qualities that make it perfect for the M5.

The first is its superb efficiency. Put simply, it delivers excellent boost at low supercharger speeds and therefore at low engine speeds. Higher boost is obviously produced as engine speeds increase through the rev range, but it’s at low speeds that

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many other ’chargers are less effective.

The second big positive with the Rotrex item is that it’s significantly quieter then others on the market. While some love a loud, mechanical whine, a supercharger’s tones should never dominate an engine’s vocals and personality, especially when that engine is a burbly S62 V8.

And finally, the C38-91 is also impressively compact. It has no right to pack the punch it does being so small. But its size is key to Evolve’s kit. As previously mentioned, space comes at a premium in an E39’s engine bay.

In fact, a number of supercharger kits for this particular car position the ’charger itself low down, virtually out of sight. Doing so, though, makes it difficult to get goood belt wrap and clearance can even be a problem. However, Evolve’s kit sees the Rotrex unit sitting snuggly behind the nearside headlight, solving these complications. Also, from a purely cosmetic perspective, it looks so much more impressive when the bonnet is raised.

Aesthetically you may have noticed something interesting about the carbon fibre intake elbow. Ordinarily, carbon fibre parts are lacquered, highly polished and therefore pleasing to the eye. What you rarely see is how coarse and rough the opposite side is.

Adopting the function-over-form policy, Evolve has reversed its intake elbows. That means the ultra-smooth polished surface is on the inside as this offers a lot less

resistance and therefore maximises airflow.

Unlike the Stage 1 kit that Evolve lists for the E39, this Stage 2 setup is intercooled. If you ‘like’ Evolve’s Facebook page, you’ll have seen that countless hours of development have gone into determining the most efficient setup. Twin intercoolers were even trialled for a period, but a single air-toair unit was found to be particularly effective. Evolve has mounted this bespoke intercooler behind the offside front wing, where it’s fed ample cold air via the front bumper’s left-hand air vent. Obviously, the arch liner requires a bit of modifying but it’s a super-tidy install.

And this minimal amount of intrusion makes the kit even more appealing in our book. It’s a direct bolt-on setup. Aside from the arch liner adjustment, the only other modification is the removal of a small section of rubber cowling for clearance purposes. There’s no butchery required here and the setup is completely reversible.

There are three versions of the setup available, basically differentiated by pulley size and resultant boost pressure. The 6psi setup produces 580bhp while the 8psi version is good for 600bhp. There is even a 9psi option, but this will only be fitted to S62s running steel liners. The car we’re testing today is fitted with the 6psi arrangement. A 580bhp E39 M5? That sounds like plenty…

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The Rotrex C38-91 supercharger is used because it’s efficient, quiet and compact

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On the road, the E39 is blisteringly fast, but strangely almost feels naturally aspirated

ON THE ROAD Before stepping into the supercharged M5, we’ve been trying to work out exactly what we’re expecting from it. As you can see from the dyno charts the E39’s ultimate performance is delivered below 5000rpm – after that power increase tails off significantly up to 7000rpm. So first and foremost, we’re hoping for stronger acceleration right up to the redline.

That said, the C38-91’s design means it delivers boost very early, making huge torque available right from the off.

Characteristically, the Rotrex unit then spreads the power throughout the entire rev range. It’s more this aspect, coupled with Evolve’s attention-to-detail when it comes to power delivery that excites us, and here’s why…

While the E39 M5 is unmistakably fast, and its S62B50 undeniably brilliant, its performance is delivered with great composure. What we mean by that is in comparison to say the S65B40 V8 in the E9x M3, or the S63B44 V8 in the F10 M5, the E39’s V8 feels less urgent. The needle moves steadily around the rev counter, it doesn’t 88 PERFORMANCE BMW

fly around and you wait patiently to change gear. Granted both of those other models are significantly newer cars, and the latter benefits from BMW’s TwinPower Turbo technology. But even though the E39 isn’t much slower on paper (only 0.5s slower to 62mph than the E92 in fact), it doesn’t thrill you in the same way. It’s not better or worse. It’s just a different driving experience. With Rotrex’s progressive supercharger strapped on, though, and with the smooth power delivery that Evolve’s ECU tuning always gives, we wondered how the driving characteristics would change.

Time to find out…

Nestling into the driver’s seat, the first thing we notice is that there are no unnecessary gauges and dials present. It feels positively stock in here and we like it.

We turn the key, the V8 snarls into life and we’re straightaway reminded that the S62 is wearing a pair of Evolve’s free-flowing headers. It’s a delectable noise. “This is the quieter of our exhaust systems,” Imran from Evolve smiles as he navigates us off the industrial estate and points us in the

direction of the closest country lanes.

The short drive across town along with a little light traffic means there’s ample time for the car to warm up. What we’re surprised about is how original the car feels, aside from the fruity exhaust system that is. There’s no lurching despite being on and off the throttle; it’s all very sedate. A VW Touareg peels off to the right from in front of us and we’re left facing a pair of national speed limit signs.

Time to squeeze the throttle…

Wow, this feels strong, but it doesn’t really feel supercharged! The E39’s pulling and accelerating much harder, but it almost feels naturally aspirated. The rush of air from the TIAL blow-off valve during each gear change reminds you that’s not the case, but we’re a little perplexed. It’s almost like you’re driving a stock M5, but someone’s pressed the fast forward button and it’s performing at x1.5 speed!

Okay, let’s be a little more objective about this. We decide to try a number of second and third gear pulls, so shift early to drop the rev needle nice and low. It’s the E39’s torque that’s always been its strong point, so does Evolve’s

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Where power increases start to level off from 5k on a standard M5, the supercharged car carries on up to 7k. The Rotrex’s excellent boost even at low engine speeds can also be seen

kit affect this? Pressing the right-hand pedal, we’re expecting the S62 to feel a bit laboured.

This is a big car, we’re three up and there’s a slight incline in front of us. We couldn’t be more wrong. There’s absolutely no hesitation from the V8 and the unbelievable supply of torque in its locker room is instantly unveiled.

We’re in third gear and the setup has just made mincemeat of the early few thousand rpm, but we keep our toe in. The power delivery is silky smooth. The needle moves round the clock with pace, but at no moment on its way to 7000rpm has there been a notable change in its speed as the system ‘comes in on boost’. It’s been ‘on boost’ from the moment we thoughabout putting the pedal down!

Interestingly, there’s been no dip in acceleration after 5000rpm either. Instead, the E39 continues to pull strongly and at no point, at any rev or in any gear, has it indicated that it might let off. This car is blisteringly fast and the two characteristics we wondered about and mentioned earlier have both been addressed. The M5 has become a lot more urgent in its power

delivery throughout the rev range, while its top-end tail-off no longer exists.

The longer we spend behind the wheel of this car, though, the more we start to appreciate something else about it: it still feels like an E39 M5. This is not so much a transformation in performance, it’s a progression. If you love how your E39 drives, you will love this setup from Evolve.

It doesn’t lose any of the M car’s personality or drivability, even when making your way through town or sitting in traffic. It’s effortless and beautifully comfortable. But in terms of acceleration, it does everything better. It pulls significantly harder, but isn’t aggressive. With the Stage 2 kit in place, your E39 will be in true supercar territory in terms of outright pace and performance.

Bearing in mind we’ve been driving the 580bhp version and more powerful setups are also available, we’re very impressed…

APPLICATIONS AND PRICE Evolve’s Stage 2 Supercharger Kit is a direct bolt-on setup for the E39 M5. It’s intercooled and comes complete with injectors, crank

pulley, TIAL 50mm blow-off valve, bespoke intake and all the ancillaries required for an almost completely reversible installation.

The kit is controlled by an Evolve AlphaN ECU program.

Three different versions are available: 6psi (580bhp); 8psi (600bhp); and 9psi (610bhp+).

Evolve recommends changing the rod bearings and strengthening the differential mounting when fitting any of its kits, but will only fit the highest power 9psi setup to an E39 with steel liners for reliability reasons.

A full health check of your M5 will always be undertaken though before beginning a supercharger conversion.

Including VAT, Evolve’s Stage 2 conversion retails at £9000, but to celebrate the launch of the new kit, free fitment is currently being offered at the specialist’s Luton-based headquarters l

CONTACT : Evolve Automotive Web: www.evolveautomotive.com Tel: 0871 231 1001

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