MAHLE 51097CP.020 Standard Piston Ring Set Bore Oversize - 3.780 0.020 L4

The MAHLE 51097CP.020 is a standard replacement piston ring set engineered for four-cylinder (L4) engines with a 3.780-inch bore diameter and a +0.020-inch oversize specification, designed for use in engines that have been bored or honed during a rebuild. This set includes four complete ring packs — one per cylinder — featuring cast iron construction with ring thicknesses of 2.0mm (top compression), 2.0mm (second compression), and 4.75mm (oil control).

Part of the MAHLE Original line — formerly marketed under the Perfect Circle brand — these rings are trusted by professional engine builders and technicians worldwide. MAHLE is the world's largest manufacturer of piston rings, leveraging decades of OEM-level research and development to deliver superior aftermarket replacement components.

Key Features:

• +0.020" Oversize — engineered for cylinders bored 0.020" over standard to restore proper piston-to-wall clearance
• Cast iron construction — delivers high tensile strength, high yield strength, and excellent hardness with low ring mass
• Stress resistance and long service life — minimizes groove pound-out and ensures excellent cylinder conformability
• Low friction design — promotes oil economy and effective blow-by control
• CP-20 oil ring assembly — features a 20-degree ear angle for optimal side sealing against the cylinder wall, with a chemically polished expander for enhanced oil drainback
• Pre-lapped finish — rings seat quickly, virtually eliminating extended break-in periods

The MAHLE Original 51097CP.020 piston ring set is an OEM-quality replacement solution for engine rebuilds requiring a 0.020-inch overbore. Ring materials, coatings, and tension levels are all application-optimized to deliver reduced friction and extended service life right out of the box.