MAHLE 42079CP.040 Premium Plasma-Moly Piston Ring Set 3.386 in. Bore +0.040 Oversize L4

The MAHLE 42079CP.040 is a premium plasma-moly piston ring set engineered for 4-cylinder (L4) engines with a 3.386-inch bore diameter at +0.040-inch oversize — a standard rebuild specification for worn or re-bored engine cylinders. This set includes compression rings with thicknesses of 1.2mm, 1.5mm, and 2.0mm, providing a complete sealing solution for engine rebuilds and overhauls.

MAHLE Original piston ring sets are engineered with installer-friendly design as a priority. Each set is pre-lapped to seat immediately, virtually eliminating traditional break-in time and getting rebuilt engines back on the road faster. Ring materials, coatings, and tension are all precisely optimized for reduced friction and extended service life in each specific application.

Key Features:

• Plasma-moly top compression ring for superior wear resistance and fast seating
• Barrel-faced compression ring contact area for more efficient combustion sealing
• CNC-controlled gap chamfer on compression rings to optimize compression and minimize blow-by
• Reverse twist intermediate ring design for enhanced groove side sealing and taper-race machined contact surface
• CP-20 oil ring assembly with exclusive 20-degree ear angle for maximum side seal against the cylinder wall
• Special chemical polish on oil ring expander for enhanced oil drain-back performance
• Sold as a complete set for one cylinder
• +0.040-inch oversize bore (3.386 in.) for re-bored or worn L4 cylinders

MAHLE is a world-leading OEM and aftermarket manufacturer of piston rings, with over 100 years of trusted performance. The 42079CP.040 is built to OE standards, making it the ideal choice for professional engine rebuilds requiring precision fitment and long-term durability.