Mahle PowerPak 99.75mm Bore Piston and Ring Kit Subaru WRX / STI EJ25 2004-2021

Mahle's PowerPak piston assemblies for the Subaru WRX and STI includes forged pistons, piston rings, pins, and wire locks--all in one race-proven package. The pistons are hand-deburred and then coated with dry phosphate to protect against ring micro-welding and pin galling during initial startup. For additional performance, Mahle added its proprietary Grafal anti-friction coating to the piston skirts. Low drag rings, steel pins, and round wire locks complete the Mahle PowerPak package.

Specs:

• Bore (in):3.917 in.
• Bore (mm):99.750mm
• Piston Style:Dish, with four valve reliefs
• Piston Material:Forged aluminum
• Compression Distance (in):1.209 in.
• Piston Head Volume (cc):+22.00cc
• Wrist Pin Style:Press-fit or floating
• Pin Diameter (in):0.906 in.
• Gapless:No
• File Fit:No
• Top Ring Thickness:1.2mm
• Top Ring Material:Steel
• Top Ring Facing Material:Gas nitrided
• Second Ring Thickness:1.5mm
• Second Ring Material:Iron
• Second Ring Facing Material:Cast iron
• Oil Ring Thickness:2.8mm
• Oil Ring Material:Stainless steel
• Oil Ring Tension:Standard