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When Patrick Brown rolled his Cummins-powered truck into the Ultimate Callout Challenge (UCC) earlier in 2025, it marked the culmination of nearly a decade of work. Brown, owner of MoonLight Diesel & Fab, has spent the last eight and a half years transforming a former five-speed daily driver – from a funeral home – into a purpose-built competition machine. His compound-turbocharged 6.7L VP Cummins is now the centerpiece of his racing program.
From Daily Driver to UCC Contender
The truck began life as a straightforward pickup, towing equipment and running errands before Brown acquired it. “It was a one-owner truck until I got it,” Brown recalls. “It just snowballed into what this is. I had a vision that I wanted to do over the years, and it’s been a work in progress.”
What started as a daily driver transitioned into a King of the Street (KOS) regular, and now, for the first time, into the spotlight at UCC. Along the way, the Cummins engine underneath the hood has evolved dramatically.
Building the 6.7L VP Cummins
Originally, Brown ran a 5.9L Cummins, but repeated block failures prompted a switch. “We kept splitting the side of the factory 5.9L blocks down the coolant passages,” he explains. “Every year it seemed like I was doing that once or twice.” The solution: swap to the 6.7L platform.
The current engine features a standard-bore 6.7L Cummins block with main studs, a girdle and Wagler Street Fighter rods anchoring the bottom end. Pistons are standard Mahle units that have been fly-cut by Haisley Machine to provide valve reliefs.
Up top, Brown recently upgraded to a Fleece Performance / Freedom Racing Engines cylinder head. “It’s one of their largest street heads you can do before cutting the shelf off,” he notes. The head is filled with Fleece valves, springs and hardware, while additional valvetrain strength comes from Manton rocker bridges, ARP rocker studs and Hamilton pushrods. A custom-cut camshaft optimized for the VP 6.7L platform rounds out the valvetrain, tailored to make power from idle to 4,000 rpm.
Air Delivery: Compound Turbos
Airflow is handled by a compound-turbo setup designed with the help of Fenley Precision Induction. The manifold charger, nicknamed “The Felony,” is paired with a 107mm atmospheric charger up front. “They go hand-in-hand pretty well,” says Brown. “That turbo has shown nothing but success for us so far, and we haven’t found the breaking point yet.”
At full tilt with nitrous, the compound system produces roughly 106 psi of boost. Brown’s future turbo plans are to step into triple-turbo territory with further help from Fenley.
Fueling the Beast
To feed that much air, Brown relies on custom Dynomite Diesel Products (DDP) injectors, flowing around 98 liters per minute. Built specifically for the 6.7L VP swap, the injectors feature unique bodies and spray patterns tailored to the engine. A Scheid pump and modified 6.7L injector tubes finish out the system.
Brown believes he may be running the largest VP-style injector set ever built. “We haven’t found the limit of those yet,” he says. “I’ll keep throwing fuel at it until we do.”
Nitrous and Electronics
The truck carries three nitrous kits – two on a progressive Maximizer 5 controller and a third 375-shot single-button system used strictly for the dyno. Staging the nitrous progressively down track helps clean up smoke and optimize power delivery.
A custom standalone ECU and harness package from Diesel Specialties handles engine management. Tuning is done through Quadzilla’s Wi-Fi-based system, which demands stable voltage. After a nitrous-related backfire at a previous event, Brown beefed up the electrical system to maintain voltage stability under heavy load.
Power and Performance Goals
On the dyno, Brown’s Cummins has already shown four-figure capability, with 1,301 horsepower recorded on a previous setup. With the new compound arrangement and fresh cylinder head, he has his sights set higher. “I’d like to make 1,400–1,500 horsepower this year, reset my personal best, and set the new industry record again,” he says.
On the track, his personal best ET is a 6.48-second pass, and he’s aiming to better that. For the sled pull portion of competition, Brown is confident in his setup and weight reduction compared to previous events. “The ultimate goal is just to finish, set some personal goals, and enjoy the fellowship,” he says.
Patrick Brown’s 6.7L VP Cummins represents the dedication and ingenuity of grassroots diesel competitors. From splitting factory 5.9L blocks to designing one-off covers for a VP-pump 6.7L, Brown has engineered his way into the elite ranks. With compound turbos pushing past 100 psi, a fueling system that hasn’t yet found its limit, and 1,500 horsepower within reach, Brown proves that persistence and creativity pay off in the world of competitive diesel performance.
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].
