ZRP RODS – SUBARU 2.5L EJ25 WRX-STI PISTONS SET

Subaru EJ25/EJ257 pistons are designed for moderate to high-performance tuning, primarily for road racing or club racing cars looking to develop their engines for high mileage and/or street use. Designed by ZRP engineers and manufactured in Germany from a high-silicon, low-expansion 4032 (T6) alloy. This allows the engine builder to use a closer piston-bore clearance, resulting in better sealing. This minimizes the slapping noise during cold starts, common among engines using forged pistons, ensuring quiet operation and low oil consumption.
We chose a full-round skirt design with a lower reinforcing band, with oversized and deeper valve pockets to allow the use of high-lift camshaft profiles. They have offset pins for quiet operation, and the wrist pins are made of 9310 alloy. Other features include anti-knock grooves to protect the first rings, and a gas pressure accumulator groove for improved ring sealing and vibration reduction. A pack of premium Japanese-quality 1.00 mm x 1.20 mm x 2.80 mm rings is included.Product Features and DesignAnti-knock grooves for long life and high performanceGas pressure accumulator groove in the second ring for increased wear resistance.Horizontal slots in the pin hole designed to allow oil to penetrate between the pin and the pin hole area.Precision CNC machined ring groovesHigh-silicon/low-expansion 4032-T6 alloyHoned pin holesSide gas ports for improved ring sealingFull-round skirt with lower reinforcement band for high HP/boost applicationsValve pockets designed to accommodate oversized valves and high-revving camshafts Pistons designed to optimize squish for longer engine life and increased power potentialOptional coatings available upon request”Blast Off Bronze” Thermal Barrier Coating”Stealth Black” Side-Skirt and Under-Crown Moly CoatingAdditional InformationApplication EJ25 / EJ257 WRX-STi (2004-UP)Bore Sizes 100.00MM, 99.50MM, 99.75MMWeight Gr. 402, 405, 407Stroke 79.00mmCompensation Ratio 8.5:1OEM Compensation Ratio 8.0:1Compensation Height 30.70mmRod 130.45mmPin Diameter 23.00mmDeck Clearance -0.35CCS Dome -19.90cc, -20.30cc, -20.70ccRing Set21-GNH1000, 21-GNH9950, 21-GNH9975Wrist Pin Pn WP082