CP Piston & Ring Set for Subaru EJ257 WRX STi - Bore (100.5mm) - Size (+1.0mm) - CR (8.2) - Single

This listing is for a single CP Pistons forged piston and ring set, specifically designed for the Subaru EJ257 WRX STi engine. You'll receive one piston and a complete set of rings to match, ready for installation. This set is built for a 100.5mm bore, which is a +1.0mm overbore from the factory specification, and features a compression ratio of 8.2:1. These are intended for engine rebuilds where improved strength and performance are key goals.

CP Pistons are well-known for their robust construction, and this forged piston is no exception. Forging the aluminum allows for a stronger, more durable piston that can handle the increased stresses of a performance engine build. The 8.2:1 compression ratio is a notable change from stock, often chosen to accommodate modifications like turbo upgrades or different fuel types, allowing for more boost or a different tuning approach. The included rings are designed to seal effectively with the piston and cylinder wall, ensuring good compression and oil control.

When rebuilding your EJ257, using a quality forged piston like this one is a solid choice for reliability and performance. Remember that this part cannot be shipped to California due to CARB regulations. Always consult your engine builder or a trusted mechanic for specific installation procedures and compatibility with your complete engine build.