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

This is a single forged piston and ring set from CP Pistons, specifically made for the Subaru EJ257 engine found in WRX STi models. If you're rebuilding the top end of your EJ257, these pistons are built to handle the demands of a performance engine. They feature a 99.5mm bore, which is the standard size for this application, and a compression ratio of 8.2:1. This lower compression ratio is often chosen for builds that plan to use forced induction, like turbochargers, as it helps prevent detonation under boost.

CP Pistons are well-known for their robust construction. These are forged pistons, meaning they start as a solid block of aluminum that's heated and hammered into shape. This process creates a much stronger and more durable piston than cast aluminum, making them ideal for high-performance and racing applications where increased cylinder pressures are common. The set includes the piston and the necessary rings, ready for installation into your EJ257 block.

Keep in mind that this piston set is not CARB approved and cannot be shipped to California. Always refer to your engine builder's recommendations and the manufacturer's installation instructions for proper fitment and assembly procedures.