GETTING 650 TO 700 HP OUT OF STOCK 6.7L POWER STROKE INJECTORS…

GETTING 650 TO 700 HP OUT OF STOCK IS EASIER THAN YOU THINK

STOCK 6.7L POWER STROKE INJECTORS…

The high-pressure common-rail fuel system itself is a major reason such clean, efficient power can be extracted from the 6.7L Power Stroke. Operating at 29,000 to 30,000 psi makes for optimum atomization and a near-complete burn in-cylinder. While the CP4.2 no doubt has its well-documented reliability issues, this compact, twin-piston, cam-driven pump—which is designed with 39,000psi capability—can still support more than 550 hp in OEM form. More on higherflowing CP4 pumps in a bit.

Before prescribing a recipe for getting to the 650 or 700-rwhp mark, it pays to take a look at the parts and pieces that make big power possible on the 6.7L Power Stroke platform. The Bosch-sourced piezo electric common-rail injectors are quick-firing (they’re capable of performing five events per power stroke) and with the right amount of duration, rail pressure, and airflow they can make more than 700 hp possible.

If you’re ready to play with your 6.7L Power Stroke, a decade-old track-record of stock bottom ends holding up to 650 rwhp should give you the confidence you need to get started. But even better than that, it doesn’t take a laundry list of mods to get you there. In fact, with a larger turbo, an upgraded CP4.2 or dual highpressure fuel pumps and good tuning, you can knock on the door of 700 -rwhp without even touching the factory injectors. Throw in the fact that a factory, non-abused 6R140 TorqShift can handle 650hp regularly and turning up the wick on a 6.7L Ford becomes even more appealing.

Factory internals, injectors, transmission, and 650 hp? The same can’t be said for any other engine and transmission combination in the diesel truck segment. No wonder so many ’11-’19 Ford owners add horsepower to their trucks. With the line in the sand for ’11-’16 engines being somewhere between 650 to 700 hp before carnage strikes (and close to that for ’17-’19 power plants), we’ll

Connecting rod strength was questioned early on in the 6.7L’s production run, but in conjunction with good tuning the stock rods aren’t a concern until you surpass the 650hp mark. What exactly do we mean by “good” tuning? A performance calibration that avoids big torque. A tune that doesn’t call for block-cracking, rod-bending, and piston-breaking fueling at low rpm but that instead pours on the timing up top is ideal for keeping rods alive. Sure this kind of tuning leads to subtle sacrifices in low-end torque, but nothing is lost in the middle of the horsepower curve, and peak horsepower is completely unaffected.

Believe it or not, the factory lift pump has proven adequate in supporting more than 700 hp when a single high-pressure fuel pump, such as a stroker CP4.2, is in the mix. That’s right, the electric fuel supply pump that’s part of the factory fuel conditioning module can be left to do its thing while you double your truck’s horsepower output. With dual high-pressure fuel pump systems, supply pressure can drop below 50-53 psi, triggering a warning on your truck’s message center (keep reading for a solution for that scenario).

It’s believed by some that the ’17 (Job 2)-‘19 connecting rods can handle more horsepower (and especially torque) than the rods found in earlier engines. And, while the late-model rods are stronger than the ’11-Job 1 ’17 versions, the verdict is still out on exactly how much more power they can tolerate before bending (or worse). Though they possess a stronger beam and utilize a slightly larger diameter wrist pin (35mm vs. 34mm previously), living in the 700-rwhp zone is probably still dangerous territory.

Up top, you’ll find two more factory components that need to undergo zero modifications in order to cope with 650 hp: the cylinder heads. The cast-aluminum, reverse-flow heads on the 6.7L Power Stroke don’t necessarily flow more than conventional cylinder heads, but a design that places the exhaust manifolds in the valley and that calls for far less exhaust plumbing makes for a more efficient overall package. As far as head gaskets are concerned, the 6.7L’s six bolt per cylinder arrangement means the heads remain glued to the block, even when boost exceeds 40 psi.

The 6.7L Power Stroke’s robust valvetrain, which makes use of a rocker arm oiling manifold, has no issue handling 700 hp. Unique to any V-8 diesel to ever grace the pickup segment, the 6.7L features four valves, four rockers, and four pushrods per cylinder. This eliminates instances of floating the valve bridges, and because each rocker possesses its own pushrod side-loading is greatly reduced. Another advantage is the reduced pivot wear on the rockers themselves, not to mention the valvetrain is quieter.

First things first, when it comes to readying an ’11-’14 Super Duty for 650-rwhp, the stock turbo has to go. And being that the factory turbo on the first-generation 6.7L Power Stroke was the dual inlet (dual compressor wheel) yet highly restrictive Garrett GT32 SST, it’s more than a simple, turbo swap. The entire turbo system has to be scrapped. From there, you’ve got two options: a fixed geometry turbo configuration which makes use of a T4 (or even T3) BorgWarner or Garrett, or a VGT retrofit kit which equips the engine with a ’15-newer style GT37 or GT37-based charger. KC Turbos’ comprehensive retrofit kit is shown.

For those working with a ’15-’19 engine, it’s obviously more budget-friendly to swap out the factory GT37 for a larger VGT. A 63mm or 64mm drop-in VGT can get you to 650-rwhp, and a 66mm can push you beyond it with the right high-pressure fuel pump(s). A setup similar to the one shown here—complete with a 66mm VGT and Dual Fueler kit from Midwest Diesel & Auto, along with spot-on PCM tuning—put down 668 hp and 1,248 lb-ft of torque on the chassis dyno.

show you how easy it is to get there. And for those of you looking to lean on your 6.7L Power Stroke even harder, we’ve got a mods list for that, too. From 600 to 650 hp, 650 to 700 hp, and 700 -plus (and a little about the carnage that can result from it), school is now in session.

When Ford introduced its revised (440 hp, 860 lb-ft) ’15 model year 6.7L Power Stroke the engine came with a Bosch CP4.2 that flowed 9-percent more fuel volume than the outgoing pump. That might seem small, but with a ’15 CP4.2 swap and a turbo upgrade performed on an ’11-’14 6.7L Power Stroke you’re right at the 600hp mark. Obviously, for ’15-’19 6.7L Power Strokes, this means a drop-in VGT upgrade can get you to the 600-rwhp mark without having to change anything on the fuel side of things. However, in either case a stroker pump or dual high-pressure fuel pumps is required to go after 650-rwhp or more.

When it comes to stroker CP4.2 pumps, the biggest names in town are Exergy Performance and RCD Performance. Exergy’s pump features a cam with a 10mm stroke, outflows a factory ’15-’19 pump by more than 30-percent, and can support 800-rwhp, although we think the company is fairly conservative in that estimate. RCD’s in-house chassis dyno testing has verified that its 10.3mm Thumper pump can support more than 850 hp. The stroked RCD unit flows 33-percent more than a factory ’15-’19 pump.

The biggest horsepower number we’ve seen produced by an ’11-’14 Super Duty equipped with a stock ’15 CP4.2 was performed by this truck. With nothing more than the late-model high-pressure fuel pump, a 64.5mm S300 SX-E, and wellrounded tuning, 647 hp was cleared on the dyno. The BorgWarner was equipped with the larger 80mm turbine wheel (vs. the 76mm that’s also in BorgWarner’s arsenal) and a 1.00 A/R T4 exhaust housing.

Although the stroker CP4.2 pumps are the preferred method of ensuring a 6.7L Power Stroke maintains rail (primarily due to cost), dual high-pressure fuel pumps are still available, and they work very well. The systems, which add a belt-driven CP3 essentially where a 6.7L engine’s second alternator would mount, can support huge horsepower—especially when a 10mm (or larger displacement) CP3 is combined with a 10mm CP4.2.

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As we alluded to earlier, the factory electric lift pump can support a single high-pressure fuel pump, no problem. This means it has no issue keeping 55-60 psi worth of fuel pressure on tap for a 10mm stroker pump at all times. But when a second high-pressure fuel pump enters the equation, the stock pump can’t quite keep up. At this point, a 220-gph Titanium Signature Series system from FASS is a common go-to for replacing the factory fuel conditioning module.

BorgWarner’s S300 frame, fixed geometry turbos are right at home on a 6.7L Power Stroke. Sized between 63mm and 69mm, they can support 625 to 700 hp and are very drivable. The S366 SX-E shown here would go on to help its ’14 F-250 produce nearly 690 hp on the rollers. By now, a common theme for making 650-plus horsepower should be obvious to you, and it’s also the case here. In addition to the 66mm S300, the setup consisted of dual high-pressure fuel pumps (a CP3 over the factory CP4.2), factory injectors, and reputable custom tuning. Due to not having the ability to restrict exhaust flow in order to accelerate the vehicle like a VGT can, a fixed geometry turbo will naturally produce significantly lower drive pressure. This lends itself to less torque being produce at low rpm, an ideal situation for an engine sporting the factory rotating assembly. On top of that, lower drive pressure is easier on head gaskets, as well as the turbocharger itself.

But with less drive pressure available as opposed to a VGT, why is a 6.7L Power Stroke so drivable with a fixed geometry turbo feeding it? As we alluded to previously, it starts with the efficiency of the reverse-flow head design. Compared with conventional V-8 diesels, the location of the 6.7L’s exhaust manifolds in the valley means less piping for exhaust energy to travel through. Just look at the short length of the up-pipes… It’s no wonder the 6.7L Power Stroke spools a big S300 so well. Of course, its displacement advantage over previous Power Stroke mills (namely the 6.4L and 6.0L) also aids its ability to bring a sizable fixed geometry turbo to life quickly.

Moving beyond the S300 realm, larger frame turbos have been tried with success on stock bottom end 6.7L Power Strokes. However, while a big single plays into the strategy of limiting low-rpm torque, they do have the ability to produce well north of 700 hp and push the engine into the danger zone if you’re not careful (or your tuner isn’t). Surprisingly, the 6.7L Power Stroke spools a moderately sized S400 or (in this case) Precision turbo very well. Also notice the CP3 near the fan shroud, which indicates that this ’11 is definitely pushing the limits of both fuel and air on a factory rotating assembly.

If you thought treading lightly with a stock bottom end was required for a big single turbo, it’s extremely important to tune around making big torque with compounds in the mix. Here, the owner of a ’19 F-350 decided to leave the engine’s factory fuel alone other than tuning and install No Limit Fabrication’s add-a-turbo style compound system. By retaining the stock, 61mm GT37 VGT in the valley and mounting a 76mm Precision in front of it as the atmosphere unit, enough air is on tap to support 800 hp. However, to keep the rods in the block, not even the factory CP4.2 was upgraded. The result was a squeaky-clean, ultra-responsive Super Duty making between 600 and 625 hp on 100-percent stock fuel.

An S400, larger nozzles, dual fuelers, aggressive tuning, and a truck clearly making more than 650 hp culminated in this form of compression loss. When the misfire surfaced the owner immediately knew what had happened, and thankfully was already rounding up parts for an engine build, which included Carrillo rods.

S moke d ro d be a ri ngs we re t he re s ul t o f t hi s ’ 17 F -350 ow ne r’s m iss i o n t o ma ke more t h an 800- rw hp o n t he s t o ck bo tt o m e nd. G oi ng b i g , 6 0-pe rc e nt over i n jec to r s , a 1 0 mm Exergy C P 4 .2 , a n d a n 8 2 mm over 63m m c o mpound t u rb o a r range m e nt was i n s t al l e d. Al t ho ugh t he f a ct o r y tra ns m i s s i on’s ab ilit y t o c o pe w i t h t he ad d ed powe r wa s t he own er ’s pri m a r y concern, t h e e ngi n e qui ckl y l et hi m k n ow t ha t i t wa s t h e bi gger weak l i nk. In f act, the f actor y bottom end di d n ’t la st an enti r e day w i t h t he new f ound power. Judgi ng by how hard the truck p u lle d u n d er powe r, a n e st i mat ed 9 0 0 hp was on tap bef ore the f ai l ure.

This one is a big no-no unless you have a spare long-block on standby, a big bank account, don’t really need your truck every day, or consider yourself lucky: compounds that add a larger VGT in the valley and a big secondary out front. With well north of 800-rwhp possible in this type of arrangement, it’s beyond playing with fire on a stock bottom end.

When you roll the dice on a stock bottom end, this can be the result. This 6.7L was saddled with compounds, dual high-pressure fuel pumps, aggressive tuning, a built transmission, and making between 725 to 750-rwhp when a rod windowed the block. With this power level not being an uncommon failure point for the 6.7L Power Stroke’s factory rods, it’s part of where the 650 to 700 hp limit stems from.

Any time you’re pursuing 650 hp or more with an ’11-’19 Power Stroke, there are a few supporting mods that should be considered. First and foremost, the factory 6R140 transmission may take issue with repeatedly being exposed to this kind of power. It’s generally accepted that you can get away with 650 hp and roughly 1,200 lb-ft of torque for a while, but if the TorqShift survives two years at that power level consider it a blessing. If you’re weighted down by a heavy right foot, plan on going through the six-speed automatic sooner than that.

A 6R140 transmission capable of handling 650-plus horsepower will come with a multi-disc torque converter sporting a forged or billet-steel front cover to eliminate ballooning and furnazebrazed internals for unmatched strength. Other prerequisites for handling power include a billet flex plate, increased clutches in Forward, Direct, and Overdrive, a fresh transmission pump and solenoid body, proper TCM tuning and, depending on horsepower goals, a billet intermediate shaft.

SOURCES

EXERGY PERFORMANCE 616.551.4330 EXERGYPERFORMANCE. COM DIESEL PERFORMANCE PARTS, INC. (FASS) 866.455.7788 DIESELPERFORMANCEPARTS.COM KC TURBOS 480.688.7160 KCTURBOS.COM MIDWEST DIESEL & AUTO 217.718.6119 MIDWESTDIESELAUTO. COM NO LIMIT FABRICATION NOLIMITFABRICATION. COM RCD PERFORMANCE 309.822.0600 RCDPERFORMANCE.COM XTREME DIESEL PERFORMANCE 888.343.7354 XTREMEDIESEL.COM

Don’t forget to work a set of traction bars into your horsepower budget. Even before the 650hp level, rear axle wrap and leaf spring twist is a concern on ’11-newer Super Duty’s. Traction bars keep the rear axle planted and the tires digging, not to mention they limit driveshaft plunge, eliminate differential twist, and are easier on U-joints, pinion yokes, and driveshafts. A quality set of traction bars won’t be cheap, but they will allow you to truly enjoy putting power to the ground—and a quality set won’t make noise while doing it.

A final word of advice is specific to owners of ’11-‘16 engines: no

matter which route you go with your turbo upgrade, get rid of the factory intercooler pipe. The plastic cold-side pipe is known to explode under boost. A bead-rolled stainless steel pipe, quality boots, and T-bolt clamps makes for a solid replacement that can handle the added boost the engine will produce. H&S Motorsports’ intercooler pipe upgrade kit, available from our friends at Xtreme Diesel Performance, is shown here.

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