5.9 Cummins Long Block

The D&J Precision Machine Performance Series 5.9 Cummins Long Block is engineered to deliver unparalleled performance and reliability for high-powered Cummins engines. D&J Precision Machine is recognized as a leader in the Cummins performance industry. This long block comes fully assembled from the oil pan to the rocker box, featuring D&J's X-Beam Stock Length Billet Rods and a Stage 2 High-Performance Cylinder Head. It is custom-built using premium components from Cummins, Mahle Clevite, and ARP, and is rated to handle up to 1200 hp, making it ideal for demanding, high-performance applications. The engine undergoes a rigorous build process, including comprehensive inspection (disassembly, crack-checking, blasting, cleaning), precision CNC machining (boring, line boring, surfacing, girdle and stud machining, torque plate honing), and fire ring grooves cut into the cylinder head and block, paired with custom ARP 9/16" head studs for a superior seal. The Stage 2 Performance Cylinder Head features heavy-duty seats, 5-axis CNC porting, and is hand-lapped and pressure-checked. Key build components include D&J X-Beam Billet Rods, OEM Cummins Pistons, D&J HD Girdle with ARP Main Studs, D&J ARP Head Studs, fire-ring sealing, D&J HD Pushrods, the D&J 250 CFM Stage 2 High-Performance Cylinder Head, a performance cast cam, new OEM tappets, oil cooler, oil pump, crankshaft seals, and billet soft plugs. Optional upgrades such as billet valve covers and timing covers are also available.