CP Piston & Ring Set for Subaru EJ257 WRX STi - Bore (99.5mm) - Size (Standard) - CR (8.2)

CP Pistons is well-known for making strong internal engine components, and this forged piston and ring set is a prime example of their work for the 2004-2012 Subaru Impreza. If you're rebuilding the engine in your EJ257 WRX or STi, these pistons are designed to handle the demands of a high-performance build. They feature a standard bore size of 99.5mm and a compression ratio of 8.2:1, which is a common setup for turbocharged applications where you want to maintain good drivability while allowing for increased boost pressure.

Forged pistons like these are significantly stronger than cast pistons, making them ideal for engines that will see higher cylinder pressures and temperatures. This strength comes from the manufacturing process, where the aluminum is heated and then forced into shape under extreme pressure, aligning the grain structure of the metal. This results in a more durable and reliable piston that can withstand the rigors of performance driving. The set includes the necessary rings, ensuring you have the core components needed to get your engine back together.

When installing these pistons, it's important to follow the manufacturer's recommended clearances and break-in procedures to ensure their longevity. Remember that this piston set is not CARB approved and cannot be shipped to California. Always consult your engine builder or a trusted mechanic for specific installation advice and to ensure all necessary supporting modifications are made for your build.