Pro Stock engine increased block strength over the 5.9L crankcase and a 6.7L block. Further improving strength and reliability, the block’s water jackets are filled with concrete. It’s been machined to accept a girdle, 14mm ARP main studs (vs. the 12mm factory fasteners), cylinder sleeves and fire-rings, and incorporates a one-inch thick deckplate up top to keep the combustion area of each cylinder from distorting. A balanced rotating assembly consists of a stock 6.7L Cummins crankshaft, R&R Racing Products connecting rods and ultra-low compression (12:1) Arias pistons. A Wagler Competition Products 12-valve cylinder head—treated to heavy port work, oversized Inconel intake and exhaust valves, roller rockers, chromoly pushrods and a one-piece valve cover—anchors to the 6.7L-based block by way of 14mm ARP head studs. In order to clear the removable hood (and because Cox didn’t want to have to lift the truck’s body), the engine is cocked slightly toward the passenger side fender.
Capable of flowing more than 1,000cc of fuel, but typically set at the 800cc mark, is one of Scheid Diesel’s 14mm P-pumps. The high-flow P8600 houses 14mm plungers and barrels, a quick-rate cam and sports an RSV (“Ag”) governor. The big injection pump benefits from dual supply lines and a gear-driven Daryl Saucier Racing (DSR) lift pump feeding it 50 psi worth of fuel pressure. Pressurized diesel leaves the P-pump through large diameter (0.120-inch) stainless steel injection lines and a set of Scheid’s triple-feed injectors equipped with 5×0.030-inch injectors (five holes in each nozzle, with each measuring 0.030 inches) mix fuel with the compressed air in each cylinder.
Pro Stock class rules dictate that a single turbocharger must feed the engine and that the turbo has to be of a smooth bore design. All air must pass through the compressor wheel inducer, which can be no larger than 3.6 inches (roughly 92mm) in diameter. Despite these limitations, this turbo from Hart’s Diesel moves enough air to support 1,850hp. It builds between 50 and 55 psi of boost during the course of a pull.
With so much fuel on tap and the incoming air compressed to more than 50 psi, intake temperatures can crest 500 degrees F. To cool things back off before entering the head, boosted air is routed through this water-to-air intercooler. Highly efficient, the system drops incoming air temperatures from 500 degrees to as low as 70 degrees, meaning cooler, denser, horsepower-friendly air is all the engine ever sees. This one component is just as responsible for the Cummins’ 1,850hp output as its wild injection system or top-of-the-line turbocharger is.