MAHLE 51510CP.040 Plasma-Moly Engine Piston Ring Set 0.040 Over

The MAHLE 51510CP.040 is a plasma-moly coated piston ring set designed for engine rebuilds requiring a 0.040-inch overbore. MAHLE, the world's largest manufacturer of piston rings, engineers these rings to OE-quality standards, delivering reliable compression sealing, reduced blow-by, and long service life.

The plasma-moly coating on the top compression ring provides exceptional wear resistance and faster break-in, making this set a preferred choice for professional engine rebuilders and performance enthusiasts alike. The ring set includes all rings needed per cylinder — top compression, intermediate, and oil control assembly.

Key Features:

• Plasma-moly top ring coating for superior wear resistance and reduced break-in time
• Barrel-faced compression ring contact surface for efficient sealing and reduced blow-by
• Reverse-twist intermediate ring design for improved groove side sealing
• CP-style oil ring assembly with 20-degree ear angle for optimal cylinder wall contact and enhanced oil drain-back
• 0.040-inch oversize bore specification for use with bored or worn cylinders
• Pre-lapped finish for immediate seating with minimal break-in required
• OE-level materials and tolerances trusted by professional technicians

MAHLE Original piston ring sets (formerly Perfect Circle) have been trusted by professional automotive technicians for over 100 years. Each set is engineered to deliver high tensile strength, excellent hardness, and low ring mass — resulting in stress resistance, minimal groove pound-out, and good blow-by control with low friction.