600 HORSES, SMOKE-FREE
FLEECE PERFORMANCE ENGINEERING’S VNT CHEETAH FOR THE FORD 6.7L
With the clean diesel era now in full swing, enthusiasts are beginning to embrace emissions-compliant performance. After all, most of us don’t want to blatantly void the warranty on our $80,000 trucks, or go tearing into a brand-new vehicle. Thankfully, fears of trashing the diesel particulate filter and blowing through gallon after gallon of DEF have begun to subside—and in the case of this article, it’s been proven that the 6.7L Power Stroke can support 580 rwhp with the factory emissions systems in place. The hidden benefit of making DPF-ON modifications is that no one else will expect your truck to run so strong. The modern diesel sleeper is a smokeless truck. They’ll never see it coming. During in-house testing of their own ’18 F-350, the folks at Fleece Performance Engineering discovered that custom tuning could push the new Fords into the 540hp range—but they also knew more power could be gleaned from added airflow. And since Fleece is in the business of building high-flow, direct-replacement variable-geometry turbochargers—namely the renowned VNT Cheetah line—the crew set about designing a drop-in unit for the 6.7L Power Stroke. To see the finished product installed and tested we trekked over to Fleece’s Brownsburg, Indiana, facility. By the end of the day the company’s tuned, emissions-friendly dually would pick up another 40 rwhp with the 63mm Cheetah in the mix.
If you’re looking to give your tuned 6.7L Ford a competitive edge, this stealthy turbo upgrade is just right for you.
THE MODERN DIESEL SLEEPER IS A SMOKELESS TRUCK. THEY’LL NEVER SEE IT COMING.
On the drive side of the Cheetah, a 10-blade turbine wheel with a 66mm exducer is utilized. The larger-than-stock turbine provides vastly improved flow at higher rpm, but thanks to the variable geometry design of the factory-based Garrett GT37, lowrpm response isn’t sacrificed in the least. In fact, when combined with precise custom tuning (with optimized vane functionality), the torque curve is broader than what the factory turbo offers. The job of tearing into the 6.7L Ford and replacing the stock turbo was left in the hands of Fleece’s lead technician, Jake Richards. First things first, Richards drained both cooling systems (the primary system is dedicated for the engine, while the secondary system is used for the water-to-air intercooler, EGR system, and transmission and fuel coolers). The low-mile coolant would be reused later.
Beginning with ’17 model year engines, Ford began using a small oil filter that protrudes into both the turbocharger’s center cartridge and the pedestal. Equipped with a tiny internal screen, it serves as an added insurance measure against debris from the block making its way into the turbo’s oil supply circuit.
After draining both cooling systems, Richards moved on to the removal of the factory air intake, intercooler pipes, throttle valve, and the upper and lower intake manifold. From there, the driver-side up-pipe was loosened, while the passenger-side up-pipe and the downpipe were removed.
With its coolant lines, oil lines and all four pedestal bolts removed, the factory turbo was ready to be pulled off the engine. After manhandling the turbo forward in the lifter valley in order to clear the cowl, Richards was able to hoist the factory Garrett up and out of the way.
Once the stock turbo had been pulled, Richards made quick work of separating it from the pedestal. After being cleaned up and hit with a coat of black paint, the factory pedestal would be swapped over to the Cheetah charger.