Mahle Motorsport Piston Set for BMW N54 engine. 84.0 or 84.5mm Bore, 89.6mm Stroke, 145.05mm Rod, 22mm Pin. Choose 10.2:1 or 9.5:1 CR. CR calculated at 0.75mm above deck and 1.22mm head gasket thickness. PowerPak Plus 2618 Alloy & Hard Anodized Top Ring Groove For Extreme Duty Applications