Mahle PowerPak 99.5mm Bore Piston and Ring Kit Subaru WRX / STI EJ25 2004-2021

Part #: 930285117. Mahle's PowerPak piston assemblies offer a race - tested solution all in one package. It includes forged pistons, piston rings, pins, and wire locks. The pistons are carefully hand - deburred and then coated with dry phosphate. This coating safeguards against ring micro - welding and pin galling during the engine's initial startup. To boost performance, Mahle has applied its unique Grafal anti - friction coating to the piston skirts. The package also features low - drag rings, steel pins, and round wire locks. Specs: Bore Size 99.5mm, Wrist Pin Size 23.0mm, Piston Material 2618 Forged Aluminum, Compression Height 30.7mm, Piston Ring Size 1.2 1.2 2.8mm, Piston Type Dish - 22cc, Crankshaft Stroke 79.0mm.

Using this Mahle piston and ring kit is straightforward. First, make sure your engine is clean and free of debris before installation. Follow the manufacturer's guidelines to correctly fit the pistons, rings, pins, and wire locks into your Subaru WRX or STI EJ25 engine. When starting the engine for the first time, be gentle as the dry phosphate coating on the pistons needs time to work its magic in protecting against ring micro - welding and pin galling. For maintenance, regularly check the pistons and rings for any signs of wear or damage. If you notice any issues, it's best to consult a professional mechanic. Keep the engine well - lubricated to ensure the Grafal anti - friction coating on the piston skirts continues to reduce drag and boost performance.