They are designed to replace BMW part #11240618006 in the BMW M30B25

no boring or honing required

CNC machined in-house at RK’s Texas facility and made from heat-treated 4130 Chromoly steel

and Alpina B3 Bi-Turbo

BMW S63 Forged Piston Set, Pro-Xtreme, Alusil X1 20iX They are designed to replaceThese pistons are suitable for use in engine blocks with factory alusil bores, no sleeving is required. Recommended piston to wall clearance is ~0. 0025 0. 0035 in 5150 AutoSport Pro Xtreme Forged Pistons for BMW S63 Engines Upgrade your BMW S63 enginefound in the F90 M5, F91 F92 M8, and X5M X6M modelswith 5150 AutoSports Pro Xtreme Forged Pistons, made in collaboration with CP Carrillo. These pistons are built to handle extreme horsepower, intense