MAHLE 50452CP.040 Perfect Circle Standard Piston Ring Set Over - 040

The MAHLE 50452CP.040 is a Perfect Circle standard piston ring set ground to .040" oversize for use during engine rebuilds and overhauls requiring a bored or worn cylinder to be restored to proper tolerances. Formerly marketed under the standalone Perfect Circle brand, these rings are now produced under the MAHLE Original banner — trusted by professional engine builders and automotive technicians for over 100 years.

Key Features:

• .040" oversize specification for use in cylinders bored 0.040" over standard
• High tensile strength and high yield strength construction with excellent hardness and low ring mass
• Engineered for stress resistance, minimal groove pound-out, and extended service life
• Optimized cylinder conformability for reduced oil consumption and improved blow-by control
• Low-friction design reduces internal engine drag for improved efficiency
• CP-series 3-piece oil ring assembly featuring a stainless steel expander between two chrome-faced steel rails for superior conformability within the cylinder bore
• Ring materials, coatings, and tension levels optimized for each specific application
• Installer-friendly design helps prevent incorrect installation

MAHLE is the world's largest manufacturer of piston rings, with deep OE engineering expertise driving innovations including narrow compression rings, steel compression rings for gasoline engines, and low-tension oil rings. The Perfect Circle / MAHLE Original standard ring line reflects that OE-level technology in a direct-fit aftermarket replacement. Ideal for engine rebuilds, re-ring jobs, and overhaul projects requiring .040" overbore rings.