OEM Piston Ring Kit for Subaru Boxer Engines

Restore tight compression and clean running with a premium ring pack built for Subaru flat-four cylinders. This kit is needed when rebuilding, after high mileage, or if oil use and blow‑by rise. Proper sealing brings back power, smooth idle, and lower emissions.

Why this part is needed

Compression rings trap combustion pressure so each stroke delivers full power. The oil control ring meters lubricant on the liner, stopping oil burn and plug fouling. Fresh rings protect pistons, cylinder walls, and catalytic converters.

How it works ⚙️

Heat makes the steel rings expand, pressing against the honed bore. Gas pressure loads the top ring, creating a tight seal. The expander-backed oil ring scrapes excess oil, returning it to the sump. Coated faces reduce friction and wear for long life.

If worn or broken ⚠️

Signs include low compression, slow starts, misfire, blue smoke, high oil use, and fuel smell in the oil. Continued driving can score cylinders, raise crankcase pressure, and damage O2 sensors and the catalyst.

Tech notes ✅

• Measure end gaps in-bore; adjust carefully
• Light plateau hone for proper seating
• Stagger ring gaps ~120° apart
• Verify groove clearance and ring orientation

Compatibility

• Legacy
• Impreza
• Forester
• Exiga