The Partee Racing S85 stroker longblock combines a billet Arrow 82.7mm stroke crankshaft with stock length Carrillo or Arrow rods, Partee Racing's proprietary JE 2618 alloy pistons with DLC pins, race-proven BMW S62 piston rings, and Schrick 292/280 camshafts and new hydraulic lifters to achieve 5.74l of displacement and wheel horsepower in the mid- to high 500 range, depending upon exhaust, intake and tune. Machine work includes boring and decking of the block and installation of headbolt inserts in our RMC-V40 CNC, honing of the cylinder walls in our Sunnen SV-10, and re-exposure of the silicone from the aluminum substrate of the cylinder walls in our semi-manual hone until we reach the requisite surface roughness characteristics (Ra, Rvk, Rpk, Mr1 and Mr2) as confirmed by a digital profilometer on a cylinder by cylinder basis. Cylinder heads are decked, lightly ported and finished by hand, an a competition multi-angle valve job performed. Proprietary Partee Racing valvesprings are installed. Stock valves are reconditioned and back-cut to improve flow at the seat. Out of spec valve guides are replaced with motorsport quality guides made from Moldstar 90 when necessary at an additional charge. All components updated to the latest revisions (piston squirters, vanos and crank gears, etc.). The reciprocating assembly is computer balanced to within 1 gram. 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. Although other combinations of bore and stroke are available, this is our preferred design. Price below does not include the $4500 core charge if applicable. See the Core Charge Policy for details.
