MAHLE 42257CP Engine Piston Ring Set Premium CP-Series

The MAHLE 42257CP is a premium CP-series engine piston ring set engineered to OE form, fit, and function standards. MAHLE is one of the world's largest original equipment piston ring manufacturers, and this set reflects the same advanced engineering and materials found in OE applications — designed for engine builders who demand reliability, reduced friction, and extended service life.

Constructed from SAE 9254 high-alloy steel, MAHLE piston rings deliver superior tensile and yield strength, extended fatigue resistance, and increased material hardness compared to standard steel alloys. Ring materials, coatings, and tension values are all optimized for reduced friction and long-term durability in each specific application.

Key Features:

• Pre-lapped for fast seating — seats immediately upon installation, virtually eliminating traditional break-in time
• Barrel-faced top compression ring — promotes more efficient compression and reduces blow-by
• CNC-controlled gap chamfer on compression rings for optimized sealing precision
• Reverse-twist second (intermediate) ring — improves groove side sealing with taper race machining for enhanced contact
• CP-20 oil ring assembly — exclusive 20-degree ear angle provides optimal side sealing against the cylinder wall; chemically polished expander promotes superior oil drain-back
• SAE 9254 high-alloy steel Napier second rings — available in grey iron and ductile iron BT and RBT configurations for best-in-class oil control
• Designed to minimize engine oil consumption and reduce ring mass while maintaining sealing performance

MAHLE piston ring sets are installer-friendly and trusted by professional engine builders worldwide. Each set is manufactured to exacting OE tolerances, making the MAHLE 42257CP an ideal choice for engine rebuilds and performance applications requiring proven, long-lasting ring technology.