Cummins 6.7L With Compound Turbos

Published in the December 2009 Issue December 2009 Cummins, PowerStroke, Turbos

CumminsFord's current engine may have an advantage with its sequential turbos. But that doesn't mean it's the only new emissions diesel engine that can take advantage of two turbo chargers.

We found this twin-turbo 6.7L Cummins while dropping off a truck at Dynomite Diesel Performance earlier this year. After testing a few different 6.7L Cummins setups over the year, this truck caught our eye, so we took it for a spin.

The truck showed up at DDP with a DPF-delete exhaust already in place. The DDP compound turbo kit consists of an S300 and S400 charger package, with a 62 mm compressor wheel in the S300 and a 74 mm compressor wheel in the S400. The kit uses DDP's own 5-ply hump boot between the two chargers that have a 220-psi burst rating. It is an exceptionally clean kit.

In order for the engine's head to handle the added boost pressures, ARP head studs were installed. It's important to note that when installing head studs, the best way to ensure proper torque, and therefore proper head seating, is to install the studs to spec, install the head nuts and drive the truck until it reaches full operating temperature. You want the block to get good and hot. Then let the truck sit overnight and come back and remove the nuts, break the studs loose and re-torque them to spec. You will get an additional quarter-turn out of them with this process and will have a solid, reliable head seal.

DDP also shimmed the in-seat valve springs to prevent them from being pushed back under compression.

The 6.7L has a stock CP3 and a set of Dynomite 80 horsepower injector nozzles for a little extra fuel for the compounds.

The transmission had some Sun Coast treatment to handle the added power and torque.

Driving the truck was a dream, especially if you are a fan of the newest Cummins engine. It builds loads of low rpm torque and rockets down the road with one of the smoothest power curves we've ever felt. It spools super quick and builds boost up to and over 60 psi in a rapid, controllable manner. And it was completely smoke-free during our test drive in Monroe, WA. For towing, this setup would be ideal with all of its low-end power coming out of the compound chargers.

Take that, 6.4L Power Stroke elitists.


Dynomite Diesel Performance

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