Any time you plan to add considerable horsepower to your truck, you must start somewhere. While some owners have no problem forking over enough cash to perform a one-and-done build, most builds take place in steps. The latter option was the preferred course of action for this ’12 Ram 2500 Mega Cab. With the owner’s long term goal being to transform it into a 700hp daily driver, he got started with a turbo swap and lift pump upgrade. Down the road, the late model Ram will also be the lucky recipient of a built 68RFE, head studs, a 10mm CP3, and larger nozzles.

Stainless Diesel’s complete S400 single turbo kits come with everything you need to bolt an S400 onto your 6.7L Cummins. That includes the S400 of your choice (an S465/83/.90 in our case), a Stainless Diesel T4 exhaust manifold, hot-side intercooler pipe, boots, air intake with S&B filter, downpipe, oil lines, and all necessary gaskets, fittings, and mounting hardware. This particular kit, spec’d with a polished manifold and cast wheel turbo, retails for $2,798.
Getting started at Flynn’s Shop in Alexander, Illinois, technician Jake Bosie drained the truck’s coolant, pulled the air intake, and removed the factory hot-side intercooler pipe (shown). Stainless Diesel includes a new, 3-inch diameter hot-side pipe (complete with bead rolled ends) in its S465 single turbo kit.
From the factory, the Holset HE351VE VGT utilizes engine coolant to keep the center section cool. However, because BorgWarner’s S400 series turbochargers only make use of oil to keep center cartridge temps in check, the coolant line shown here gets eliminated.
With the banjo bolt removed from the front passenger side of the block just behind the oil filter, this threaded plug was installed in its place (which is included in Stainless Diesel’s single turbo kit). From there, the heater core, turbo feed, and EGR coolant line were removed.
Next, the factory exhaust manifold bolts were removed (with the exception of the bolts located at the front and rearmost runners) and the manifold gaskets pulled. We’ll note that new exhaust manifold bolts come standard with the Stainless Diesel single turbo kit, while new manifold gaskets are an optional item (they can be had for an additional $59).
After removing the remaining gaskets and bolts in the factory exhaust manifold, it was ready to be pulled out of the engine bay. Thanks to a helping hand, Bosie was able to leave the factory turbo attached to the exhaust manifold and remove them both as one complete assembly.
While the factory turbo oil drain location in the block is reused with the Stainless Diesel single turbo kit, the factory turbo oil drain itself is scrapped (shown). In addition to supplying a new (longer) oil drain tube to reach the S400’s higher mounting location, Stainless Diesel also includes a new 4-inch diameter, aluminized-steel downpipe.
With the S465 charger in the mix, the factory VGT wire harness is no longer necessary. But instead of removing the wire harness altogether—in case it needs to be reused one day—Bosie simply wrapped the connectors in electrical tape and left them tucked in close to the block.
In order to no longer route coolant to the turbo, the multi-purpose factory hard coolant line is done away with and replaced with the one shown here, supplied by Stainless Diesel. The new coolant line sends antifreeze directly from the water pump to the factory heater core hose and attaches via rubber boots and worm gear hose clamps.
If you opt for Stainless Diesel’s polished option (a $200 charge), you’re in for a treat. Cosmetically, its manifold can’t be beat. For equal flow, inside runner diameters measure 1.650 inches throughout, and the unit’s ¾-inch thick center section lends itself to extra porting if it’s ever needed.
A big key to Stainless Diesel’s second-gen 24-valve exhaust manifold spooling an S400 so well rests in its design. Through years of R&D and testing, Stainless Diesel has found that facing the exhaust manifold upward, such as in a second-gen application, adds significant efficiency to common-rail Cummins engines (i.e. quicker spool up, more power, and an extended power curve). Also noteworthy, its one-piece design means it’s void of the stepped sections found in competing two and three-piece units (which actually hamper internal flow).
With both 1/8-inch and ¼-inch ports incorporated into the Stainless Diesel manifold, Bosie got to work transferring the EGT probe. To ensure the EGT probe could safely be removed from the original exhaust manifold, it was first treated to a round of heat via a Power Probe micro torch.
The first step in installing the Stainless Diesel exhaust manifold included the installation of the supplied turbo-to-manifold mounting studs. With our manifold incorporating four threaded holes, Bosie simply threaded in the supplied studs until each one had bottomed out.
Here you can see the EGT probe after being transferred over to the Stainless Diesel manifold. The second port, included for measuring drive pressure, was plugged with the supplied ¼-inch brass plug.
When it was time to attach the Stainless Diesel manifold to the head, Bosie threaded in the top bolts for both the front and rearmost ports first. Then, the manifold gaskets and mounting bolts for the middle four ports were installed. After that, the top bolts for the front and rearmost ports were removed, their respective new gaskets were installed, and the rest of the bolts were threaded in.
The supplied exhaust manifold mounting bolts and optional manifold gaskets offer peace of mind in a job like this. While some opt to reuse the factory exhaust manifold gaskets, it’s good practice to start with fresh ones anytime the manifold is removed. Bosie made sure each manifold bolt was coated in anti-seize before installing it, and also torqued all fasteners to the recommended 32 ft-lb spec.
Turning his attention to the turbo, Bosie installed the supplied oil feed fitting on top of the center cartridge and added a small amount of fresh engine oil for the journal bearings. Stainless Diesel also includes a braided stainless steel oil supply line with its S465 single turbo kit, with the option of upgrading to an extreme duty, -6 line for an additional $55.
Known in the industry as a “box charger,” the BorgWarner S465 is a stout performer and retails for less than $1,000. It features a cast compressor wheel with a 65mm inducer and a V-band connection point at the compressor housing outlet. For a $99 upcharge, Stainless Diesel will throw in a polished compressor housing.
On the exhaust side of the S465, the popular 10-blade, 74/83mm turbine wheel is employed within a 0.90 A/R housing. While a 0.90 A/R exhaust housing might seem a bit tight in a performance application, it’s perfect for a stock fuel truck. When larger injectors are introduced, a looser housing (i.e. bigger A/R) can be run to keep drive pressure down and high-rpm flow up. A looser housing can be had for less than $300.
To provide enough clearance between the turbo’s compressor housing and exhaust manifold, Stainless Diesel includes the 1-inch thick, divided T4 spacer shown here. Two divided T4 flange gaskets are supplied as well (one for the manifold side and one for the turbo side).

Thanks to the displacement advantage the 6.7L Cummins has over its 5.9L predecessor, it has no problem lighting a large single turbo. In fact, a T4 flange S400 is right at home on the 6.7L mill and—depending on which size you choose— can spool surprisingly quick. Picking a charger with utmost streetability but that could also flow enough to reach his eventual power goal, the owner settled on Stainless Diesel’s complete S465 single turbo kit. In preparation for future fueling upgrades, a 150-gph FASS fuel system and a fuel tank sump from Beans Diesel Performance would also be installed.

The process of bolting the turbo to the exhaust manifold was simplified by separating the compressor housing, compressor wheel, shaft, and turbine wheel from the exhaust housing and installing the exhaust housing first. Once the supplied nuts had been fully tightened to the exhaust manifold threads (via 15mm wrench), the turbo was re-assembled in the engine bay.
Once the supplied 90-degree cast-aluminum elbow was clamped to the compressor housing outlet, the new hot-side intercooler plumbing was finagled into place. Squeezing the twopiece hot-side pipe where it needed to be required Bosie to mount the grid heater relay in a slightly different location.
Once the supplied 90-degree cast-aluminum elbow was clamped to the compressor housing outlet, the new hot-side intercooler plumbing was finagled into place. Squeezing the two-piece hot-side pipe where it needed to be required Bosie to mount the grid heater relay in a slightly different location.


This before and after shot illustrates how exciting things have become under the hood—and it’s only the start. With a turbo capable of supporting 700-rwhp, phase two of the build is already in the works: 60-percent over nozzles, a stroker CP3, and (of course) a built 68RFE.
A 150-gph Titanium series fuel system from FASS fits right into the owner’s future power goal, as it’s ideal for trucks making between 600 and 900 hp. A readily-available, spin-on 10-micron FS-1001 water separator and 3-micron FF-3003 fuel filter keep fuel free of water and debris, and ½-inch hose supplies ample fuel volume to the CP3.
Working in conjunction with the FASS system is a tank sump from Beans Diesel Performance. To ease the installation process, Beans’ sump employs a single bolt design and O-ring seal, comes with a 3-inch hole saw and all stainless hardware, and can be installed without dropping the fuel tank. The Beans sump also features an internal stand pipe (cut into the inside of the sump) to reduce sediment from entering your fuel system.

If you plan to pursue a similar power goal with your 6.7L Cummins, this is a solid first step. Take it from us, the finished product drives very well. Even at low rpm, you barely notice that the factory VGT is no longer there—and the truck doesn’t even have larger injectors yet.DW






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