Forged Piston Set (Factory Specs), Mahle - E9X M3

Mahle Motorsports S65 pistons are forged for strength, light weight, and low drag to be a more specialized application than stock BMW pistons. Factory BMW pistons are cast aluminum, which is fine for the intended power output and durability. But increase the performance, especially on turbo- or supercharged engines, and the cast aluminum becomes a weak link at some point. The strength of cast parts is susceptible to heat, detonation/knock, and other timing or fuel issues. These types of combustion forces can make it brittle or even deform the piston shape or size. Forged pistons are inherently a stronger material and more robust in these extreme conditions.

This is a piston that shares the factory specs - only .01mm larger bore (+.0004") but with a lower compression for boosted applications.

Full specs -
Bore: 92.00mm
Stroke: 75.2mm
Rod length: 140.7mm
Compression height: 27.3mm
Pin diameter: 21mm
Piston crown volume: 2.1cc
Weight: 366g
Compression ratio: 10.1:1

Mahle Motorsports pistons are better engineered than mass-market OEM pistons. Quality and machining is much more tightly controlled, ensuring superior performance. Mahle uses a Grafal coating on piston skirts that reduces drag, friction, scuffing, and cylinder bore wear and a phosphate coating on other surfaces.

All pistons include a ring set, wrist pins, and circlips.

Made in the USA.