MAHLE 51106CP.030 Perfect Circle Standard Piston Ring Set Over - 030

The MAHLE 51106CP.030 is a Perfect Circle standard piston ring set ground to a 0.030-inch overbore specification, designed for engine rebuilds and re-ring applications requiring precise oversize fitment. Formerly sold under the standalone Perfect Circle brand, this ring set is now part of the trusted MAHLE Original lineup — a name professional engine builders have relied on for over 100 years.

Key Features:

• Cast iron construction — provides high tensile strength, excellent hardness, and low ring mass for long service life
• 0.030-inch overbore sizing — engineered for cylinders bored 0.030" over standard for precise fitment and proper ring seal
• Optimized ring tension — reduces friction while maintaining effective compression sealing and oil control
• Stress-resistant materials — minimize groove pound-out and promote consistent cylinder wall conformability
• Good blow-by control — supports oil economy and low friction throughout the ring's service life
• Installer-friendly design — rings are precision ground and designed for straightforward installation during engine overhaul
• OE-derived technology — MAHLE's extensive OEM development program drives advances like low-tension oil rings and narrow compression rings into every aftermarket set

MAHLE is the world's largest manufacturer of piston rings, and the Perfect Circle heritage brings over a century of engineering expertise to every set. The 51106CP.030 is the correct choice for engine rebuilders working with bores opened up to the 0.030-inch oversize specification. Sold as a complete set.