Piston Terminology

FSR (Forged Side Relief) forging designs feature a reduced skirt width and shorter wrist pin when compared to traditional “full round” style forgings. The narrow skirt helps minimize piston contact with the cylinder wall that can cause friction and power loss while the shortened wrist pins reduces the overall weight. Some FSR forgings feature internal and external bracing to provide a more rigid construction while minimizing overall weight. With thousands of race miles logged in the most demanding applications like NASCAR, NHRA Pro Stock and Indy Car, these pistons provide the ultimate combination of low-friction, lightweight design with increased stability and strength.