Precision Dimensions for Big Performance

The block sports a 9.240″ deck height with 4.115″ cylinder bores and 4.400″ bore centers, perfectly engineered for aggressive builds while maintaining true LS compatibility. Five billet steel main caps, all four-bolt and cross-bolted, keep the crank planted no matter how hard you push. Torque the studs to 75 ft-lbs, the cross bolts to 30 ft-lbs, and you’ve got a bottom end that laughs at high RPMs and boost alike.

Rebuildable and Engineered for Longevity

Each cylinder comes with a replaceable dry ductile steel sleeve, pressed to exact tolerances for maximum durability. Builders can safely bore up to 4.165″, opening the door to serious displacement upgrades. And with priority main oiling and dry-sump provisions, this block ensures your engine gets the lubrication it demands under even the harshest conditions. Screw-in freeze plugs, cam plug, all dowel pins, and pipe plugs come included—this block is ready to go straight from the box to your build.

Built for Builders

Every detail of the BMP‑086515 is designed with the engine builder in mind. Standard GM LS bearings, camshaft placement, and lifter bores make assembly predictable, while the block’s LSX head bolt pattern and drilled-and-tapped motor mounts give you flexibility for retrofits or high-performance swaps. From oil passages to bearing alignment, Bill Mitchell has dialed in the details so your build goes smooth and fast.