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Scrapping the 6.7L Cummins failure-prone VGT for the proven BorgWarner S400

Posted in How To: Engine on December 19, 2017
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If you had no choice but to replace a factory component on your truck that failed prematurely, would you opt for an OEM replacement that’s likely to meet the same, untimely fate, or would you spring for a more reliable aftermarket alternative? How about if a guaranteed performance gain was on the table and the “forced” upgrade could essentially be had for the same cost?

After experiencing a turbocharger failure at just 114,000 miles, the owner of this 6.7L Cummins-powered ’14 Ram 2500 wanted no part of giving another OEM unit a try. Instead, BD Diesel’s Rumble B Turbo Kit piqued his interest. The BD system replaces the failure-prone factory variable-geometry turbo with a proven fixed-geometry unit, comes with a high-flow exhaust manifold, and even includes a cold-air intake assembly.

With a time-tested fixed-geometry BorgWarner turbo in the mix, the 6.7L Cummins sees less drive pressure (saving the head gasket), a reduction in peak exhaust gas temperature (easier on the engine), and an increase in boost (more power). Tag along as we install the BD Diesel system and spotlight the fundamental parts that make this commonsense turbo swap worthwhile.

With its variable-geometry design and built-in exhaust brake function, the Holset HE351VE turbo that leaves the factory aboard the 6.7L Cummins is a marvel of modern engineering. Unfortunately, like a lot of variable-geometry turbochargers, it doesn’t hold up like the simpler fixed-geometry units used in the days of old.
Constant exposure to soot, carbon buildup, and corrosion tends to immobilize the moveable parts within the exhaust housing of the factory Holset HE351VE, and its electronically controlled actuator is known for premature failure. When regular cleanings aren’t observed (for both the turbo and its actuator), there is definitely a point of no return with the stock turbo.
Centered around a fixed-geometry BorgWarner S300 or S400-framed turbo, BD Diesel’s Rumble B kit is a 100 percent bolt-on system that’s available for all ’07.5-’16 Rams (note that kits for ’07.5-’09, ’10-’12, and ’13-’16 model years are slightly different). The kit includes BD’s Race exhaust manifold, a hot-side intercooler pipe, intake and intercooler boots, oil and coolant lines, and a 4-inch downpipe and kit-specific cold-air intake (not shown here). The all-inclusive Rumble B system in this story retails for $2,925, while a stock (problematic) ’13-’16 turbo can cost more than $2,600 at the dealership.
Although six different turbo options are available with BD Diesel’s Rumble B kit, this particular buyer settled on the system that comes with BD’s version of the popular BorgWarner S467. This charger features BorgWarner’s extended tip, forged milled wheel (FMW) compressor wheel with a 67.7mm inducer, but BD fits it with an exclusive one-piece, 90-degree outlet compressor housing. The 90-degree outlet is specific to the Cummins application and rules out the need to use a separate elbow to route boost to the intercooler.
The tried and true 74/83mm turbine wheel coupled with a 1.10 A/R exhaust housing offers great drivability throughout the rpm range and keeps peak drive pressure well within the safe zone. BD rates the S467 for 700 rwhp, although we’ve seen it support well north of that in the aftermarket. Full disclosure: You do lose the factory exhaust brake function by switching to a fixed-geometry turbo system such as this (as the OEM exhaust brake is technically a turbo-brake). However, it’s a trade-off many are willing to make for vastly improved reliability and performance.
BD’s Race exhaust manifold incorporates a centrally located exhaust inlet for the turbo (a T4 flange), which provides for improved exhaust evacuation and lower exhaust gas temperature (EGT). The 20-degree pitch in its centersection design helps accommodate S400 or larger turbochargers, and pre-drilled 1/8-inch NPT ports exist for measuring EGT and drive pressure. To hold up under constant exposure to extreme heat, the Race manifold wears a coat of POR-15 High Temp paint.
After cleaning up the mounting surfaces around the exhaust ports on the cylinder head, the manifold can be secured via the four supplied (8mm) Allen bolts, which install in the manifold’s centersection. All other manifold fasteners are retained factory bolts, but BD does supply six new exhaust manifold gaskets for a fresh seal. Using the recommended center-out sequence, all manifold fasteners are torqued to 37 lb-ft.
For high horsepower applications—where excessive drive pressure could potentially overspeed the S467—BD machines a wastegate port into its Race manifold. Specifically designed to accept a 45mm TurboSmart Hyper-Gate 45 model wastegate, it’s geared toward the enthusiast pushing his or her turbo past the 700 hp mark.
For this application—a tune-only, 500hp truck still making use of the stock 68RFE automatic transmission—BD’s wastegate blocker plate and its corresponding clamp was employed in the Race manifold’s wastegate port. It would take a sizeable set of injectors, a stroker CP3, or a high dose of nitrous to warrant the need to run a wastegate in conjunction with this particular S467 turbo.
Setting the S467 in place on the exhaust manifold may call for a slight tweak to the factory A/C line for adequate clearance, but is otherwise uneventful. Once the turbo is securely mounted to the exhaust manifold, its oil drain can be installed, followed by the appropriate clocking of the compressor housing to accept the new hot-side intercooler pipe.
In our install, the grid heater solenoid had to be relocated toward the firewall prior to installing the new hot-side (passenger) intercooler pipe. The intercooler pipe itself is secured to the turbocharger’s compressor housing outlet and intercooler inlet via supplied silicone boots and spring-loaded T-bolt clamps. Before the turbo oil feed line was installed, the turbocharger’s centersection was pre-lubricated with fresh engine oil to avoid any scoring of its bearings during initial startup.
BD’s high-flow, cold-air intake assembly forces you to part ways with the factory Ram Active Air system on ’13-and-newer trucks, but we don’t think that’s a bad thing. After all, the BD system makes use of a massive 8-inch-diameter, open element air filter and a 5-inch-diameter composite intake tube, so there is no shortage in available airflow. A rubber airbox seal and a custom intake box and lid are also part of the package.
The supplied 5-inch intake tube accommodates the factory MAF sensor and air temperature and pressure sensor. Once the cold-air intake has been installed, the supplied crankcase ventilation hose can be routed from the engine to the silicone intake boot and attached via the barbed fitting and clamp. Knowing that all installs will be slightly different, BD provides generous sections of hose in its Rumble B kit, allowing the installer to cut them to length as he or she sees fit.
With the major items installed, loose ends were tied up by relocating the coolant overflow reservoir, installing the transmission dipstick tube reposition bracket, and ensuring that all clamps and fasteners were tight. After that, the downpipe was clamped into place between the turbo and existing exhaust system, followed by the installation of the BD airbox lid.
Thanks to EFI Live software, the electronic side of integrating a fixed-geometry turbo onto a 6.7L Cummins is very straightforward. In fact, after the folks at Anarchy Diesel made a few simple tweaks to the truck’s existing performance calibration, it was like the swap never even happened. Here you can see the revised Anarchy file being uploaded to the ECM via an EFI Live FlashScan V2 device.

Sources

BD Diesel Performance
Sumas, WA 98295
800-887-5030
www.dieselperformance.com
EFI Live
Auckland, NZ, AK
http://www.efilive.com
Anarchy Diesel
423-815-5582
anarchydieseltuning.com

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