2,200 Horsepower Compound Turbo 6.7L Cummins

Nov 01, 2023

Josh McCormack has made his name known well throughout Engine Builder Magazine over the years – he's been featured in our Diesel of the Week series twice, won our Diesel of the Year contest in 2020 with his 6.8L Cummins build, and hosted an Engine Builder Takeover back when he worked at Power Driven Diesel.

He's worked in the diesel industry for most of his adult life and has made a name for himself competing in various events, including back-to-back All Truck Challenge wins in 2021 and 2022. Both of those wins were backed by some kickass engines built by McCormack himself, including a powerful 6.4L Cummins in 2021.

McCormack has since left Power Driven Diesel and opened up his own diesel shop with co-owner David Petrick, who's also been featured in a previous Diesel of the Week. The Abingdon, VA-based diesel shop is called Wide Open Throttle Motorsports (WOT), which is capable of completing a bevy of Cummins engine and transmission work. From stock engine rebuilds to 2,500 horsepower Cummins powerhouses, they can do it all – in fact, many of the engines sold at WOT are replicas of today's Diesel of the Week engine. McCormack and the team call it the "Ultimate 6.7L."

"I had just won the 2021 All Truck Challenge and returned home and I didn't have any problems with that engine, but I wanted to build something that I could drive on the street and not have to worry about," McCormack says. "This one seems to take quite a beating and so far it's the hardest I’ve ever pushed one.

"I wanted something that could tow, drive well on the street, and do drag racing and pulling. Also, one of my big things is clean diesel power. I’m sure as a teenager I didn't always think like that, but in the past few years, I’ve tried to set a good example of being able to make 1,500-2,000 horsepower without smoking up the whole city. I feel as though the more we can change that image of the diesel industry, the longer it will last."

The build starts with a 6.7L Cummins block pulled out of a 2012 truck and machined by Enoch Motorsports. It has a Power Stroke Products 6.7L OEM replacement crankshaft, a set of Wagler Street Fighter rods, Mahle pistons and a Mahle ring set. The block gets reamed out and threaded for 14mm main studs for a 12-valve application.

The engine also has a Colt Cams stage 5 camshaft with tappets, Manton stage 3 pushrods and valve bridges, OEM 6.7L rocker arms, a ported cylinder head with billet freeze plugs, and a Haisley fire ring gasket. Everything is held together by ARP 625 studs.

"There's really nothing too fancy," he admits. "Although we do have Trend tool steel wrist pins, which I think is one of the things that makes our builds different. I’ve found that around 1,500-1,600 horsepower, the wrist pins that come with those Mahle pistons tend to dig in, so we like to upgrade them."

On the fueling side, McCormack decided to run a single Exergy 14mm race pump after seeing the success that Firepunk Diesel was having with it. Transferring fuel to the Exergy is an Airdog 5g lift pump. Forcing fuel into the combustion chamber is a set of 5.9L Dynamite Diesel 300% over injectors. The setup still features a factory 5.9L rail, as McCormack believes it's much easier to work on.

For air, McCormack runs a Steed Speed T4 wastegated manifold, and a Turbosmart 45 that dumps into the hot pipe. On the manifold, he's running a Forced Inductions 480/96 T6 charger and a Garrett 106mm GTX55R out in front. In order to help aid in some of that horsepower production, he runs one Maximizer 5 progressive nitrous controller from Nitrous Express and four nitrous kits – two large 375 solenoids and two smaller ones.

On fuel only, McCormack's ’07 Ram 2500 makes anywhere between 1,600-1,800 horsepower. On nitrous, that range looks more like 2,000-2,200 horsepower.

"One of the things I always get hated on for is that the truck still has a factory intake horn," McCormack says. "But the engine's made 2,183 horsepower, so I’m not complaining. To get those numbers, we’ve been increasing the rail pressure. Normally a 5.9L truck will run like 26,000 psi rail pressure, but I usually run this truck at 235 MPa, which is like 34,000 psi rail pressure. We use a Dynamite Diesel high pressure seal that can take that much so we’ve really taken advantage of it."

This year, McCormack plans on using the truck in more dirt drag events, but more than anything, just wants to be able to drive it around. Recently, he took his current setup on a 600-mile round trip to Kentucky and made 22mpg. With heated seats, air conditioning, full radio and subwoofers, he's got quite the comfortable ride.

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].