JE Pistons Subaru EJ257 Ultra Series 8.5:1 C/R 100mm Bore 83mm Stroke Piston Kit (Set of 4)

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

Additional Information

100.00 mm Bore - 28.70 mm CD - (-21.50 cc) - 4 Cyl. Piston Kit

Part Type

Engine Piston Kit

• 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.
• 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
• JE’s proprietary Aligned Grain Flow forging technology providing next-level tensile strength ideal for the extreme cylinder pressures of power adder engine builds.
• 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.
• Made 100% in the USA
• 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
• Smooth Crown Finish: Deburs all areas around the valve pocket and dome area, to reduces stress risers and prevent hot spots.
• 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.

Note for Pistons, Rings, Rotors, Rods and engine internals

Unless otherwise specified, some brands supply brake rotors, pistons, strut mounts, rods and rings separately. In some cases, titles may indicate plural, or 'set' - eg the term “ring set” often refers to the rings for a single piston only. If you’re unsure about what’s included with this product, please contact our team for clarification.

Images are supplied by the manufacturer and may be generic. While all efforts are made to provide accurate pictures, there may be differences in the actual product, such as colour, quantity, version, or included components. Please carefully review the description and specifications for details on inclusions or any variations. Some items may be sold individually or in sets, and images may occasionally depict additional products or quantities not included in your purchase. For assistance or clarification, please contact customer support.

Reference Information

Piston Kit, JE ULTRA SERIES-SUBARU EJ257 STROKER - 9