CP Piston & Ring Set for Subaru EJ255 WRX - Bore (100.0mm) Size (+0.5mm) CR (8.4) *Single Piston*

If you're rebuilding the engine in your Subaru EJ255 WRX and need a reliable piston to handle increased performance, this forged piston from CP Pistons is a solid choice. It's designed to be a direct replacement for your stock piston, but with the strength and durability that comes from a forged construction. This particular piston is 100.0mm in bore size, which is an oversize of +0.5mm, and features a compression ratio of 8.4:1. This setup is common for builds looking for a bit more displacement and power while maintaining a safe compression for boosted applications.

CP Pistons are well-known in the performance engine building community for their robust construction. Forged pistons are made from a solid block of aluminum that's heated and hammered into shape, making them significantly stronger and more resistant to detonation and fatigue than cast pistons. This strength is crucial when you're pushing an engine harder than stock, whether that's with more boost, higher RPMs, or both. The included rings are designed to work seamlessly with the piston for a proper seal, which is key for engine performance and longevity.

When installing these pistons, remember they are an oversize part, so your engine block will need to be bored and honed to the correct 100.0mm dimension to ensure a proper fit and seal. Always refer to the manufacturer's installation instructions for specific details on ring gap, piston-to-wall clearance, and assembly procedures.