Sin City Diesel's Compound Turbo 6.7L Cummins Engine
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Sin City Diesel’s Compound Turbo 6.7L Cummins Engine

Courtesy of Engine Builder.

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A lot can happen in the span of just two-and-a-half-years. Case in point, we first talked to Sin City Diesel and Off-Road owner Frank Davis in late 2019 to learn about a rebuild of a 6.6L LBZ Duramax they had done for a customer.

At the time, the one-year-old shop was divided into two 4,000 sq.-ft. facilities that offered either diesel or off-road work. The business has since expanded to a much larger 17,500 sq.-ft. space, fitting a variety of services under a single, much larger roof. The increase in space has allowed Davis to pursue more routes and opportunities for the shop, maintaining the diesel and off-road aspects while adding fabrication work and even a UTV sister brand called Sin City Xtreme Performance (check out one of their latest UTV builds).

On the diesel side of things, the shop has the capability to tackle a variety of projects, including repair work, engine rebuilds, engine swaps, suspension installs, and much more.

“We work on all three, Cummins, Powerstroke and Duramax,” Frank Davis says. “We do a lot of the early 2000s pre-emissions era trucks, from oil changes to full builds.”

Just recently, Davis reached out to tell us about a new diesel build the shop did of a 6.7L Cummins engine for the new Sin City shop truck. It only took Davis purchasing four different trucks to settle on the final product.

“I went through a phase where I was just buying and selling back-to-back,” Davis says. “I had a 2017 4th Gen mega cab and it was my dream truck. We did a bunch of work on it, but we don’t do any emissions delete stuff so there wasn’t much I could do to make power. I sold that and got a 2012 4th Gen quad cab, which I only had for about a week.”

After going through two more 3rd Gens, Davis finally settled on his current truck – a 2006 2500 mega cab. He always planned on using the Duramax platform for the shop truck, but eventually decided on a Cummins due to the platform’s more easily accessible upgradability. The build was also inspired by Josh McCormack, a friend of Davis’ who has also been featured in our Diesel of the Week series.

The original goal for the build was simple – to make a 10-second, 1,000+ horsepower combination. The team at Sin City started with the bottom end of the standard bore, un-sleeved 6.7L Cummins. The rotating assembly consists of a stock Cummins crank, 14mm main studs, Wagler Street Fighter connecting rods, and Mahle pistons with valve reliefs cut in them. Trend steel DLC-coated wrist pins were also added to the mix.

“Outside of that we did the normal balancing and made sure everything was good on that end,” he says. “It took a bit to find the right shop, but we eventually found Enoch Motorsports and had them do the machine work. The block was decked, fire rings were machined into the block and head, and it was honed to get to the desired piston wall we wanted. They did a great job.”

Up top, the engine features a Power Driven Diesel ported head with an XDP valvetrain. The truck is running OEM Cummins rockers and has XDP 7/16ths pushrods. The camshaft is a Hamilton 160/220 cast cam with the crank and cam gears welded onto both. Davis also added a Goerend flexplate and Fluidampr high power kit to assist with durability.

“We’ve got ARP 625 head studs throughout and we also got the Haisley fire ring,” he says. “We did half in the head, half in the block and have found that’s been the best way to do it, and we can continue to keep treating it.”

For the fuel system, the engine is running a set of Dynomite Diesel Products 200% over injectors and their 12mm CP3 on the engine with a stock 6.7L CP3 over top of that and a Fleece dual CP3 kit. For air, Davis decided on a compound turbo setup to maintain better streetability of the vehicle. The system consists of a Forced Inductions S472 and a Power Driven Diesel Aggressor S488.

With the final touches of the overall build still getting dialed in, Davis says the goal is to produce around 1,300 horsepower on fuel only, and north of 1,500 with nitrous. All this Cummins diesel power will be concentrated on going sled pulling later this year.

“I don’t have anything concrete planned for the truck yet, but I really want to get into some sled pulling events in the future around the area,” Davis says. “To me, sled pulling is the epitome of having a diesel truck, so that’s the goal.”

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Diesel of the Week is sponsored by AMSOIL. If you have an engine you’d like to highlight in this series, please email Engine Builder Editor Greg Jones at [email protected]

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