JE Pistons Subaru EJ25 Ultra Series 100mm Bore Dia -17.3cc 8.5:1 0.905in Pin - Piston Set

Ultra Series forged pistons from JE are the industry’s strongest, most fully featured pistons available off the shelf. Offered for Subaru STI EJ257 Engines. Ultra Series Pistons feature JE’s proprietary Aligned Grain Flow forging technology providing next-level tensile strength ideal for the extreme cylinder pressures of power adder engine builds. Equipped with the following custom level features

• Accumulator Groove: A specialty groove between the top and second ring provides added volume for blow-by gases. This helps reduce pressure between the rings, improving top ring seal and minimizing ring flutter at high cylinder pressures.
• Lateral Gas Ports: This process mills slots into the top of the top ring groove and provides a pathway for combustion pressure to get behind the top ring. Resulting in increased ring seal and is most common in circle track applications.
• Thermal Crown: Applied to the piston crown, this thermal barrier coating reflects heat back into the combustion chamber to improve exhaust gas velocity and scavenging while reducing heat transfer to help extend piston life.
• JE’s proprietary Aligned Grain Flow forging technology providing next-level tensile strength ideal for the extreme cylinder pressures of power adder engine builds.
• Pin Fit: The pin bore is precision honed to attain an exact pin clearance. Clearances typically range from .0003 to .0010 between the wrist pin and pin bore.
• Skirt Coat: Skirt Coat reduces friction and wear on piston skirts and cylinder walls while simultaneously reducing operating noise
• Designed specifically for Subaru STI EJ257 Engines. To provide optimized performance durability
• Includes high-quality wrist pins, locks, and JE Pro Seal premium piston rings
• Made 100% in the USA