MAHLE 51137CP.040 Perfect Circle Piston Ring Set 3.776 in. Bore .040 Over V8

The MAHLE 51137CP.040 is a Perfect Circle precision-ground piston ring set designed for V8 engines rebuilt to a 0.040-inch overbore. Part of the MAHLE Original line — formerly marketed under the legendary Perfect Circle brand — these rings deliver OE-quality sealing, superior oil control, and long service life for engine rebuilds and repairs.

This set features a 3.776-inch bore diameter (nominal 3.736 in. + 0.040 in. oversize), with ring thicknesses of 5/64 in. (top), 5/64 in. (second), and 3/16 in. (oil). Rings are constructed from cast iron and engineered to OE tolerances for reliable compression sealing and controlled oil consumption.

Key Features:

• Cast iron construction — barrel-faced top compression ring with positive twist for fast, efficient break-in
• Taper-face reverse-twist second ring — improved oil control and combustion gas management
• CP-20 3-piece oil ring — stainless steel expander with chrome-faced steel rails and exclusive 20-degree ear angle for superior side seal and simplified installation
• 0.040 in. oversize bore — engineered for engines bored 0.040 in. over standard for proper fit in rebuilt cylinders
• Fool-proof installation design — rings are engineered so they cannot be installed incorrectly
• OE-derived technology — narrow compression rings and low-tension oil ring designs drawn directly from original equipment specifications

MAHLE is the world's largest manufacturer of piston rings, and the Perfect Circle name has been trusted by professional engine builders and automotive technicians for over 100 years. The 51137CP.040 delivers the performance, durability, and precision required for a successful engine overhaul.