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Upgrading a Ford 6.7L Power Stroke with a ’15 Turbo and CP4.2 Disaster Prevention Kit

’15 Turbo Install & Preventing All-Out Fuel System Failure

From the 5.9L and 6.7L in the Cummins camp to every RPO code Duramax ever produced, even good engines have their share of problems. Ford’s 6.7L Power Stroke is no different—especially when looking at the ’11-’14 version. The first generation of Ford’s in-house diesel V-8 introduced the high-tech Garrett GT32 SST (single sequential turbo) variable geometry turbo and the Bosch CP4.2 high-pressure fuel pump. In relatively short order, the aftermarket discovered the shortcomings of the dual compressor VGT (namely its propensity to overspeed and lack of airflow at higher rpm), and also began to see how destructive a failed CP4.2 could be.

Luckily the same aftermarket that found the limits of the GT32 and had to repair the fuel systems wrecked by CP4.2 failure have created sound solutions and work-arounds for both problems—and we’re installing them on a ’13 Super Duty test mule this time. On the air side, a KC Warlock ’15 turbo retrofit kit from KC Turbos will allow us to replace the problematic GT32 SST with the proven ’15-later style VGT, the GT37. Then for arguably the most cost-effective peace of mind you can buy for a 6.7L Power Stroke, we’re integrating S&S Diesel Motorsport’s Gen 2.1 CP4.2 disaster prevention kit into the fuel system.

It’s pretty tight quarters when attempting to access everything you need to surrounding the 6.7L Power Stroke turbo. Trust us, when trying to reach the factory up-pipe nuts on the passenger side of the engine, pulling the truck’s inner fender well makes life much easier.
Before breaking out the wrenches, we first drained both cooling systems (remember, the 6.7L Power Stroke has a primary and a secondary cooling system). Next we went to work removing the factory air intake system and the EGR system’s coolant supply line, followed by unplugging the boost sensor. Then the cold-side intercooler pipe would be pulled off of the lower intake manifold.
Up next on the removal list was the factory upper intake manifold. After all of its mounting bolts were loose and free, the composite piece was lifted off of the engine. And because the upper intake manifold ushers air into the valve covers (and ultimately the heads) we took care to cover the exposed openings.
Here you can see the visible differences between the ’11-’14 style lower intake manifold (left) and the ’15-newer one supplied in the KC Turbos Warlock kit. One obvious difference (other than the size and weight) is that the ’15 style manifold features a single pathway for intake air to flow to the turbo’s compressor wheel.
We then moved on to pulling the factory lower intake manifold. However, before we were able to remove it we had to disconnect the factory crankcase ventilation hose. Notice here that the factory hot-side intercooler pipe has already been removed (it would be retained).
On the dyno, it’s rare to see a tuned, stock turbo ’11-’14 Super Duty make more than 460 to 480-rwhp—even with some of the best calibrating in the aftermarket. By comparison, ’15-newer trucks—which came equipped with the bigger, GT37-based turbo we’re installing in this article—can lay down 540 to 545-rwhp. While the responsive GT32 SST provides huge torque numbers thanks to lighting so quickly, it’s simply out of steam by 2,800 rpm (and sometimes even sooner).
While the Garrett GT32 SST is a neat piece, its failure rate can’t be overlooked—nor can its inability to support the kind of horsepower today’s diesel owners expect with simple, plug-and-play power adders. Thanks to its comparatively small 59mm turbine wheel, an undersized turbine shaft, and the fact that shaft speeds regularly exceed 130,000 rpm in stock form, and it’s easy to see why even the addition of a mild tuner can send the GT32 SST into orbit. In fact, overspeed in the most common failure associated with the ’11-’14 turbo.
To be sure, things are cramped on the driver side of the turbo as well. In order to gain ample room to pull the driver side up-pipe on this side, the upper and lower portions of the factory downpipe should be removed first. The beauty of the KC Turbos Warlock kit shows here. Ford’s kit requires replacing the downpipe while KC’s retains it.
When the Garrett GT32 SST debuted aboard the 6.7L Power Stroke in 2011, it was about as high-tech as a turbo could be. The GT32 SST sports variable geometry functionality, dual compressor wheels (positioned back-to-back) and two inlets, a dual ball bearing center cartridge, and an electronic wastegate to help prevent overspeed. It provided extremely quick spool up and made the 6.7L Fords the towing beasts that they were. However, it ran out of air well before 3,000 rpm, not exactly something V-8 diesel owners were used to.
Turning our attention back to the engine and the task of removing the factory turbo, its coolant and oil lines were removed, as was the factory wastegate solenoid harness (which was no longer necessary). From there, all four turbo pedestal bolts were broken free using a 13mm socket and the factory GT32 SST turbo was finagled out from under the cowl and off the engine.
There’s two common ways to retrofit an 11’-14’ 6.7L with a newer ‘15 turbo. The above is from Ford. It’s every part that changed when they released the ‘15 Fords. KC Turbos offers this kit as well as the Warlock kit we opted for. The Warlock kit uses significantly less parts and installs in a fraction of the time it takes to get the Ford kit done. It’s less money too…
So what makes the GT37 VGT so great? For starters, it’s simpler and it’s bigger. A journal bearing center cartridge (that’s easily rebuildable) and a larger diameter turbine shaft are employed, a single compressor wheel is used, and both the compressor and turbine wheels are considerably bigger. The GT37 sports a 61mm (inducer) compressor wheel vs. the GT32 SST’s dual 43mm arrangement. The GT37 also features a 62mm (exducer) turbine wheel (vs. 59mm on the GT32 SST). The larger wheels promote better intake and exhaust flow at higher rpm, which is why the GT37 can support 540-rwhp tune-only efforts on the dyno. One tradeoff is that the GT37 spools roughly 300 rpm later, but good tuning can make its drivability more than sufficient down low.
This is a common sight during any turbo removal on a 6.7L Power Stroke. Don’t worry, the KC Turbos Warlock retrofit kit comes with brand-new turbo outlet clamps and everything else you’ll need to get the job done. Not to mention the fact that it comes with the appropriate turbo pedestal to mount the KC Turbos modified GT37.
Remember the massive amount of parts in Ford’s kit we mentioned earlier? Well, this is the entire KC Turbos Warlock retrofit kit. We weren’t kidding when we said it had significantly less parts to swap out.
Using the supplied gasket, the ’15 style pedestal was attached to the GT37 and we dropped everything in as a single assembly. Thanks to its lack of a wastegate diaphragm like the factory GT32 SST had, the GT37 is much easier to squeeze under the truck’s cowl. Prospective installers will be happy to know that it’s also a slightly lighter weight turbo as well.
When the CP4.2 is finally uncovered, it pays to thoroughly clean the entire area around the pump with brake cleaner and compressed air before removing the fuel control actuator (referred to as the FCA, but also known as the VCV or volume control valve). It’s imperative that no debris makes it into the CP4.2 or any of the fuel lines during the install. The FCA was removed using a T25 torx.
With the intake and intercooler piping still out of the way, we had adequate access to the CP4.2. Needless to say it was an opportune time to begin the CP4.2 bypass kit (i.e. disaster prevention kit) installation. We got started by laying all of the pieces out in front of us and pouring over the detailed instructions S&S includes with its kit. Use of OE-style quick-connect fittings to eliminate leak points and the inclusion of a return filter to isolate debris before it’s passed on to the fuel tank are just a few of this system’s selling points. It’s also designed to work on any ’11-newer 6.7L Power Stroke.
Keep in mind that we had virtually everything removed from the top of the engine in order to install the turbo kit, so your CP4.2 bypass kit installation could vary. That said, you will want to remove the factory fuel filter housing for added working room (shown), along with the EGR tube that connects the EGR cooler to the lower intake manifold, the lower intake manifold itself, and the crankcase breather.
Revised and dare we say perfected, S&S Diesel Motorsports’ Gen 2.1 version of its CP4.2 bypass kit is the ultimate insurance item to have onboard if your 6.7L Power Stroke’s high-pressure fuel pump checks out. The primary function of the bypass kit is to independently supply the CP4.2’s case, metering unit, and plungers with clean, filtered fuel while also rerouting case fuel back to the truck’s tank. To rule out any chance of contaminated case fuel back-feeding into the clean fuel supply line, the fuel supply is split off into two separate lines, approximately 25-inches from the CP4.2 pump.
Here you can see the supplied billet filter head and Donaldson filter installed under the hood. This 9-micron, spin-on filter is deliberately positioned in the return circuit to stop debris from making it back to the tank in the event the CP4.2 self-destructs. So not only does the S&S Gen 2.1 bypass kit keep a failing CP4.2 from destroying your injectors, it also keeps the fuel returning to the tank (eventually to be re-routed toward the engine) as clean as possible. Make no mistake, S&S’s disaster prevention kit is not a Band-Aid type product. It works and can save you thousands of dollars in repairs in the event the CP4.2 fails. Look no further than the company’s website and social media channels for the real-world proof of how well it works.
S&S recommends inspecting the FCA upon pulling it. Specifically, the fine mesh screen on the end of the FCA should be clean and free of any debris. As our ’13 Super Duty was running fine when it idled into the garage, ours checked out OK, but it should be clearly stated that finding metal shavings here is a telltale sign you’ve lost the CP4.2 pump. Pulse width modulated by the powertrain control module (PCM), the FCA’s job is to control the amount of fuel that enters the CP4.2. In conjunction with the pressure control valve (PCV), the FCA also regulates fuel rail pressure.
A key piece in the disaster prevention kit is the bypass block, which accommodates the FCA on top of the CP4.2. After inserting the FCA into the bypass block, the bypass block was fitted with its supplied O-rings and the assembly was installed on the CP4.2. Allen head bolts (4mm) were supplied in the bypass kit. We torqued each one to the 60 in-lb specification recommended by S&S.
With the remainder of the S&S CP4.2 bypass kit install wrapped up, we reverted back to the turbo and intake system install. Here you can see the new lower intake manifold going in, which dropped directly in place of the original. This was followed by the hot and cold-side intercooler pipes, upper intake manifold, and the factory air intake being reinstalled. Then the cooling systems were topped back off and we were ready for the final step in the install.
In order to make the ’15 style turbo perform correctly, our ’13 essentially had to be fooled into thinking it was a ’15 model year truck. Our platform of choice used in recalibrating the PCM was EZ Lynk. Specifically, the turbo’s vane position and desired boost parameters have to be tweaked to get proper performance and drivability out of the GT37 turbo. You will definitely want to rely on a competent, reputable calibrator for the seamless, electronic integration of your ’15 style turbo.

Why A Disaster Prevention Kit Should Be On Every ’11-newer Power Stroke

In case you were wondering what transpires when a CP4.2 lets go, this is it in a nutshell. In terms of destruction and repair costs, CP4.2 failure is on the level with the damage caused when the killer dowel pin works itself loose inside an ’89-’02 Cummins. It’s a mess with all sorts of chain-reaction type damage. Once the contact between the piston/roller tappet assembly and the pump’s cam lobe begin to break down and introduce metal shrapnel into the fuel system, it’s inevitably passed on through the fuel rails, and to the injectors. Simultaneously, the return fuel circuit is contaminated, which means the tank will need to be dropped and cleaned, and the fuel supply pump may even need to be replaced.

 

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SOURCES

EZ Lynk
ezlynk.com

KC Turbos
480.688.7160
kcturbos.com

S&S Diesel Motorsport
ssdiesel.com

 

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