CP Piston & Ring for Subaru EJ257 WRX STI- Bore (100.0mm)-Size (+0.5mm)- CR (9.0) - *SINGLE PISTON*

CP Pistons is well-known for making strong internal engine components, and this SC7439-1 forged piston is a prime example of their work for performance Subaru builds. If you're rebuilding the engine in your Subaru EJ257 WRX STI, this single piston is built to handle the demands of a performance application.

This piston features a 100.0mm bore and is a +0.5mm oversize, meaning it's designed to replace a worn or damaged piston with a slightly larger diameter. It has a compression ratio of 9.0:1, which is a common target for modified EJ257 engines looking for a balance between power and pump gas usability. The forged construction means it's made from a solid block of aluminum that's heated and hammered into shape, making it significantly stronger and more durable than cast pistons, which is essential for high-performance engines.

This part is sold individually, so be sure to order the correct quantity for your engine build. Please note that this piston is not CARB approved and cannot be shipped to California.