JE Pistons Small Block Ford (20 Degree Head) 4.030 Bore / 1.600 CD / -5.00 CC - Set of 8Forged in the USA using 2618 aluminum, yielding high tensile strength needed for high demand performance applicationsProprietary Forged Side Relief (FSR) forging design minimizes friction and power loss with reduced skirt width and saves additional weight with a shorter wrist pinRing groove design placement proven to maintain positive seal in high HP, boosted applications, along with stout top land thickness for improved strengthLow friction skirt