Perfect Circle 3150032-045 Plasma-Moly Piston Ring Set 4.170" Bore +.045" Oversize

The Perfect Circle 3150032-045 is a Plasma-Moly piston ring set designed for high-output and performance engines with a 4.170-inch bore diameter at +.045" oversize. This ring set covers all 8 cylinders (V8 applications) and is built to deliver superior sealing, durability, and power retention under demanding conditions.

Manufactured under the MAHLE Original brand — the parent company of the iconic Perfect Circle name — these rings feature a plasma-moly face coating applied over SAE 9254 steel. This construction provides exceptional tensile strength, hardness, and fatigue resistance. The plasma face coating extends service life, eliminates ring breakage, reduces side wear, and minimizes groove pound-out that can occur in high-stress engine environments.

Key Features:

• Bore Size: 4.170" (+.045" oversize)
• Ring Set Coverage: Full set for 8 pistons (V8 engines)
• Tension: Standard tension
• Fit Type: File fit for precise custom gap adjustment
• Top Ring Material: SAE 9254 steel with proprietary plasma-moly face coating
• Face Coating: Plasma-moly for superior wear resistance and reduced friction
• Reduced cross-section design for lower ring mass and better conformability to cylinder bore distortion
• Top ring groove can be positioned closer to the piston crown, reducing crevice volume and unburned fuel

The smaller cross-section of these steel rings lowers ring mass, allowing the ring to better tolerate inertial forces at high RPM and seal more effectively against the bottom of the ring groove. This design also improves the ring's ability to conform to cylinder bore distortion — a critical advantage in today's high-output engines. The Perfect Circle 3150032-045 is an ideal choice for engine rebuilds requiring oversize rings with proven performance-grade materials and construction.