Piston Ring Set 4.020 Bore 1.2mm 1.5mm 2.5mm

The Piston Ring Set 4.020 Bore 1.2mm 1.5mm 2.5mm from MAHLE ORIGINAL/CLEVITE is engineered for high-performance engine rebuilds and overbored applications where precision ring fitment directly impacts compression, blowby control, and long-term reliability. This piston ring set serves engine builders, machine shops, and serious enthusiasts tackling stroker builds, top-end refreshes, or complete engine overhauls on both street and competition platforms. Oversized piston rings like this are essential when cylinder walls have been bored beyond factory specifications, requiring matched ring grooves and bore tolerances to seal properly and maintain peak performance.

MAHLE ORIGINAL's engineering delivers three-piece ring geometry with compression ring thicknesses of 1.2mm and 1.5mm, plus a 2.5mm oil control ring that manages crankcase pressure and cylinder wall lubrication under load. The 4.020-inch bore diameter accommodates engines bored 0.020 inches over stock, a common upgrade for displacement increases and improved flow characteristics in aluminum blocks. Premium materials and tight manufacturing tolerances ensure consistent gap closure, minimal friction drag, and superior sealing across the full RPM range—critical factors that prevent ring flutter, hot spots, and premature wear on freshly honed cylinder walls.

This ring set is ideal for small-block and mid-block engine applications where 0.020-inch overbore dimensions are standard—including popular platforms like Chevy, Ford, and Mopar builds. Proper installation requires a ring compressor tool, accurate piston-to-wall clearance verification, and matching ring end gaps to the specific combustion chamber and bore finish. Pairing these rings with correctly sized pistons, properly honed cylinders, and quality rod and main bearings ensures optimal power delivery, fuel economy, and engine longevity in both daily drivers and high-output applications.