PROJECT OPTIMIZED STOCK (PART 1)

Part 1: Installing Fleece Performance Engineering’s 2nd-Gen Swap Kit

Right off the assembly line, the 6.7L Cummins is a beast of an engine. Siamese cylinders, increased bore and stroke over the 5.9L, common-rail injection, and a factory exhaust brake all combine to make it a robust torque monster capable of towing just about anything. Still, the 6.7L has its drawbacks, one of which is the variable-geometry Holset HE351VE turbo’s propensity to seize up after the exhaust side succumbs to soot and carbon buildup. One of the more common solutions for a stuck turbo is to do away with the VGT altogether and install a fixed-geometry unit. Thanks to the 6.7L Cummins’ displacement advantage over its 5.9L predecessor—and when used in conjunction with a ’98.5-02 style exhaust manifold—a moderately sized BorgWarner S400 can be run with very few trade-offs in drivability.

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Available for 5.9L common-rails on through to the latest 6.7L Cummins (’03-18), Fleece Performance Engineering’s second-gen swap kits come with everything needed to replace the factory turbo with an S400. In our ’10-12 fourth-gen system this meant a 5-inch Fleece ManTake intake setup, S400 discharge adapter with hot-side intercooler pipe, stainless steel downpipe, oil feed and drain kits, and all necessary fittings, boots and clamps, along with a cast BorgWarner S467 and Steed Speed exhaust manifold.

Fleece Performance Engineering is one company that has all but perfected the fixed-geometry turbo swap process on the 6.7L. The company’s second-gen swap kit relocates the turbo mounting location to the center of the manifold with the outlet flange angled downwards. The result is added reliability, more horsepower, improved driving characteristics, as well as lower EGT and drive pressure. Once in possession of a lightly modified ’12 Ram 2500 with an ailing factory turbo, we consulted the folks at Fleece about our predicament and soon found one of the company’s ’10-12 second-gen swap kits on our doorstep. After removing the original turbo system, the Fleece kit was seamlessly installed in just five hours’ time.

This marks the beginning of a three-part series in which we’ll optimize the performance of the aforementioned stock-injector, stock-CP3, stock-transmission ’12 6.7L Cummins test mule (i.e., a tune-only truck), but also prep it for bigger and better things in the process. The scope of the project is to free up horsepower, enjoy optimum towing functionality, and support future injection system upgrades—all of which will be accomplished by installing Fleece Performance Engineering’s second-gen swap kit, Fleece’s groundbreaking exhaust brake for fixed-geometry turbo applications, and a PowerFlo in-tank lift pump. Stay tuned for the exhaust brake and lift pump installs in the coming months.

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Readying the 6.7L Cummins for its new turbo system entailed draining the engine coolant and removing the air intake assembly, hot-side intercooler pipe, and downpipe. From there, the bolts for the factory turbo oil drain were removed, along with the oil feed line.

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After unplugging the VGT actuator, loosening both coolant lines at the turbo, pulling the transmission dipstick, and backing out all manifold bolts, the factory turbo and exhaust manifold were removed as one assembly. While removing the turbo and manifold assembly as one unit isn’t easy due to its weight, it can be pulled off by strategically finagling it between the web of coolant lines, oil lines and wiring.

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For the sake of comparison, we separated the factory turbo and manifold to illustrate the difference between the second-gen-style Steed Speed unit we were installing and the OEM piece. Notice how far back the outlet flange sits on the stock manifold versus the Steed Speed. In addition to its outlet flange being positioned dead-center, the Steed Speed manifold features a larger T4 divided flange, whereas the factory piece utilizes a non-divided T3i flange. This is the primary reason the second-gen swap works so well in terms of drivability: equal exhaust flow to the turbine. As a bonus, the Steed Speed manifold comes with two 1/8-inch NPT ports for a pyrometer probe and/or drive pressure reading.

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As part of Fleece’s second-gen swap kit, the factory coolant bypass and heater core tube is replaced with a simplified coolant bypass hose but requires a new adapter and fitting. After the supplied adapter’s O-ring was hit with a coat of fresh engine oil, it was installed by reusing the factory bolts (shown). Once the supplied 90-degree swivel fitting was attached to the adapter, the oil filter had to be removed to connect the new coolant bypass hose.

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To keep the coolant bypass hose secure, we added two 7/8-inch cable clamps to the mix. One was added at the front of the block near the oil filter base (shown), and the other was threaded into an existing hole at the rear of the block, just before the coolant bypass hose curves upward to meet the heater core.

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With the coolant bypass hose connected to the heater core, we moved on to removing the factory turbo oil drain from the block. Although this double O-ringed, flexible stainless piece can be a bit stubborn to remove, surprisingly ours wiggled out with very little effort.

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Due to the factory coolant drain line for the VGT no longer being necessary, Fleece supplies a coolant delete plug that installs in the block near the oil filter. A second coolant drain is also capped off on the cylinder head. Due to some fourth-gen trucks requiring 16mm plugs while others need 18mm ones (and some even using two 16mm plugs), Fleece supplies enough plugs for either circumstance.

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Turning our attention to the new parts, we threaded the supplied turbine housing flange studs into the Steed Speed manifold. From there, we located the included T4 turbine inlet gasket and placed it over the studs.

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Because we wanted to install the Steed Speed exhaust manifold and S467 as one assembly, we removed the turbo’s compressor housing. In previous installs we’ve learned that taking this step provides for ample clearance of the battery tray and grid heater relay.

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In between pulling the compressor housing and mounting the rest of the turbocharger assembly to the Steed Speed, we broke out the caliper. Here you can see that the box S467’s cast compressor wheel measures 67mm and change at its inducer. The wheel flows just under 1,300 cfm (90 lb/min, give or take) and the off-the-shelf S467 can support 750 hp or more.

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On the exhaust side of the equation, the S467 utilizes the common 74/83mm (exducer/inducer) turbine wheel. A 0.90 A/R turbine housing, the tightest available for this model turbo, provides surprisingly adequate spool-up—even in 6.7L trucks equipped with stock injectors such as ours.

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With the exhaust housing secured to the Steed Speed manifold via the supplied washers, lock washers and nuts, the included (O-ringed) oil drain adapter was pieced together and installed in the S467’s center cartridge. Then the new oil feed fitting was threaded into the oil cooler cover (just above the oil filter) and the turbo and manifold were lowered into place.

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To get all the new exhaust manifold gaskets into place, the manifold was initially (and loosely) secured to the head via the top bolt for cylinder number 3. Then every other cylinder’s gasket was installed and held in place via its top manifold bolt. From there, the number 3 bolt was unthreaded from the head, its gasket slid in, and then it was reinstalled. After that, the bottom manifold bolts were installed and all fasteners were torqued to 32 ft-lb.

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The top exhaust manifold bolt for cylinder number 4 doubles as an anchor point for the transmission dipstick tube relocation bracket supplied by Fleece. Pulling the transmission dipstick tube toward the engine positions it away from the S467 turbo’s sizeable compressor housing.

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After setting the compressor housing back into place on the turbo, we mocked up the way the discharge pipe and air intake would have to be routed before tightening up the compressor housing band clamp. Then the grid heater relay was relocated slightly forward to provide enough clearance for the 5-inch Fleece ManTake assembly.

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With the O-ring in place on the supplied 90-degree discharge elbow, it was attached to the turbo’s compressor outlet and clocked to the orientation we’d previously determined. Although not easy to see here, the intercooler side of the discharge pipe features a lip around its outlet’s diameter to keep its respective intercooler boot from blowing off at elevated boost.

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Fitting the new hot-side intercooler pipe with the included boots and T-bolt clamps prior to attempting to finagle it between the discharge pipe and intercooler yielded the best results during its installation. Like the discharge pipe it connects to, the far end of the hot-side pipe (where it attaches to the intercooler inlet) has a bead rolled around its diameter to eliminate a blown intercooler boot scenario under high boost pressure.

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Next up, the oil supply line that spans from the oil cooler cover to the S467 was installed. We added Teflon tape to the threads of the 90-degree adapter at the turbo’s center cartridge for added insurance against leaks.

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When it came time to install the new oil drain line in the block, we pulled the truck’s inner fender liner to gain adequate access. After coating the double O-ring fitting with fresh engine oil we pressed the line into the block, connected it to the turbo, and reinstalled the inner fender liner.

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Any time you’re upgrading to a higher-flowing turbocharger it pays to add an air intake system that can match it, and the Fleece ManTake system was specifically designed for this application (an S400 with a 5-inch compressor cover inlet and a downward-angled, second-gen exhaust manifold). The first step in piecing together the ManTake system is sliding the supplied 45-degree rubber coupler over the S467’s compressor inlet.

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After swapping the mass air flow (MAF) and intake air temperature (IAT) sensors over to the composite intake tube, it was connected to the 45-degree coupler and tightened up via clamp. Then the massive, oiled, open-air filter element was maneuvered into place and tightened down as well.

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Next, we refilled the engine’s cooling system one gallon at a time until all 5.7 gallons had been replaced. Although we could’ve started with fresh coolant at this point, the truck hasn’t yet reached its 100,000-mile flush interval, so we opted to reuse it.

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Fleece supplies a 4-inch-diameter, stainless steel, second-gen downpipe with its second-gen swap kit. If you’re running a 5-inch system (like the Flo-Pro system we were), a 4-inch to 5-inch adapter will be required. A simple $25 5x4x6-inch reducer from Donaldson (P206328) was all that was needed to make everything work.

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A helping hand was needed to hook the downpipe onto the S467’s turbine outlet. By pushing upward from underneath, the downpipe flange was made flush with the turbo and the V-band clamp could be installed and tightened up.

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Because the factory VGT was removed, an ECM tuning revision was necessary. But on top of simply keeping the truck from throwing a code, the fueling curve of the engine had to be changed to optimize the performance of the S467. Tuned by Motor Ops using EFI Live software, uploaded via V2 FlashScan and navigated by way of the CSP5 switch shown here, more aggressive fueling down low makes the fixed-geometry S467 surprisingly responsive at slower engine speeds. Additionally, Motor Ops’ TCM tuning is utilized to keep the stock 68RFE automatic’s shift points crisp and where they need to be, its lockup strategy on-point, and the six-speed slushbox alive at 500-plus hp.

 

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The new location of the turbocharger is clear in these before and after photos. Visually, it’s pleasing to see an S400 lurking front and center. Audibly, the truck sounds like a 5.9L—something a lot of factory turbo 6.7L owners say they miss (which used to be us). Thanks to the Fleece second-gen swap kit, midrange and top-end power is night-and-day different from what the restrictive factory charger had to offer, and it feels like a solid 50-hp gain was realized up top. As far as the truck’s turbo system is concerned, the groundwork has been laid to support a sizeable injector nozzle upgrade and a stroker CP3 in the future.


SOURCES

BorgWarner
Turbos.BWAuto.com

Fleece Performance Engineering
855.839.5040
FleecePerformance.com

Steed Speed
250.807.7212
SteedSpeed.com