Description

The Cummins ISB Piston & Ring Kit C4089670 (0.50 mm Oversize) is a complete, OEM-spec piston kit designed for ISB diesel engines that have undergone cylinder boring during professional rebuilds. This oversize piston kit is engineered to restore factory compression, sealing efficiency, and long-term engine durability. Designed for Cummins ISB platforms , this 0.50 mm oversize kit compensates for cylinder wear or machining, ensuring proper piston-to-wall clearance and consistent combustion across all cylinders. Using a matched piston and ring set is critical to achieving correct clearances, stable oil control, and uniform compression during an engine overhaul. The pistons feature precision-machined ring lands and optimized skirt geometry to reduce friction and maintain piston stability under high operating loads. The included piston rings are manufactured from high-strength, wear-resistant materials to provide fast seating, strong cylinder sealing, reduced blow-by, and controlled oil consumption—key requirements in modern, emissions-controlled ISB diesel engines. The C4089670 oversize piston kit is commonly installed during ISB engine rebuilds, in-frame overhauls, and professional remanufacturing projects . It is trusted by diesel repair shops, fleet maintenance operations, and engine builders who require OEM-level reliability and performance.