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 a precision-engineered engine rebuild component designed for high-performance and stock engine applications requiring exact bore specifications. This three-piece ring set addresses the critical seal between piston and cylinder wall, controlling compression, managing oil consumption, and regulating heat transfer during combustion. Whether you're rebuilding a stroked or overbored engine or restoring a factory powerplant to original specifications, this piston ring set delivers the precision fit that separates a reliable rebuild from a catastrophic failure.

Each ring in the Piston Ring Set 4.020 Bore 1.2mm 1.5mm 2.5mm serves a distinct function: the 1.2mm compression ring (top) seals peak cylinder pressure and resists blowby; the 1.5mm secondary compression ring (second) provides additional sealing while reducing heat stress; and the 2.5mm oil control ring (bottom) scrapes excess oil from the cylinder wall while maintaining film thickness for lubrication. MAHLE ORIGINAL and CLEVITE manufacture these rings using premium cast iron with carefully controlled tolerances and surface finishes that ensure rapid seating and minimal blow-by, even under aggressive boost or high-RPM operation. The 4.020-inch bore dimension indicates compatibility with bores at or near 4.020 inches—typical for many V-block small-blocks and mid-displacement engines when fitted to the correct piston.

This piston ring set is essential for engine builders, machine shops, and serious enthusiasts rebuilding engines for street, drag, or endurance applications where compression integrity directly impacts power delivery and durability. Proper ring-to-groove clearance, correct installation sequence, and careful honing of the cylinder wall are mandatory to maximize ring life and prevent pegging or sticking. Always confirm your engine's exact bore size and piston specifications before ordering—even 0.005 inches of mismatch will compromise sealing efficiency and can cause catastrophic oil burn or loss of compression. Compatible with most small-block platforms using 4.020-inch bore pistons; consult your engine's technical manual or machine shop to verify fitment with your specific block and rotating assembly.