Our S85 "Better than Stock" longblock is bored out to 94mm on our RMC V40 CNC to accommodate our proprietary 2618 alloy pistons made for us by JE that tick up the stock compression to 12.5:1 and accommodate race-tested BMW S62 piston rings. The silicone in the Alusil cylinder walls is re-exposed from the aluminum substrate through a specialized honing process on a cylinder by cylinder basis until certain specific surface roughness specifications are met (Ra, RvK, RpK, Mr1 and Mr2) as confirmed by a digital profilometer. Carrillo or Arrow rods combine with a straightened (where necessary) and polished stock crank and BE or Mahle bearings to create a reasonably bullet-proof bottom end. The reciprocating assembly is then computer balanced to within 1 gram and the block and each cylinder head are decked the minimum amount and with high Ra finish to ensure perfect head gasket sealing. A competition multi-angle valve job is done, and proprietary Partee Racing valvesprings are installed with cleaned and reconditioned stock valves, seats and retainers. Valve guides that are out of spec will be brass lined or replaced with motorsport quality guides for an additional expense. New or rebuilt oil and vanos pumps are installed. All one-time use stretch bolts, tensioners, guides, chains, gaskets, and other consumables are replaced with authentic BMW parts. During assembly, all critical clearances and specs are blueprinted and provided to the customer upon request. Valve covers are powdercoated in wrinkle black and all exterior covers and pans are ceramic bead blasted for a new aluminum appearance. This is NOT a "eBay" special rebuild, but rather, a very high end rebuild that can serve as the basis for future modifications, such as camshafts and ported heads. Price below does not include the $4500 core charge, if applicable. See the Core Charge Policy for details.
