Description

The Cummins Piston 3908816 (1.00 mm oversize) is a precision-engineered diesel engine piston designed for engines that have been machined to a 1.00 mm oversize bore . This piston is used during engine rebuilds to restore proper compression, combustion efficiency, and engine performance after significant cylinder wear or damage. Manufactured from high-strength aluminum alloy , this oversize piston is built to withstand high combustion pressures, elevated operating temperatures, and continuous heavy-duty service common in Cummins diesel engines. The optimized piston crown supports efficient fuel combustion, while the reinforced skirt design helps reduce piston slap, scuffing, and uneven wear following cylinder machining. Designed for accurate fitment in 1.00 mm oversize cylinders , the Cummins 3908816 piston ensures correct compression ratios, proper piston ring seating, and smooth, stable engine operation. Using the correct oversize piston is critical to prevent blow-by, oil consumption, and premature engine failure in rebuilt engines. This piston is commonly used in Cummins diesel engine rebuild and overhaul applications , including on-highway trucks, industrial engines, and heavy-duty equipment requiring precise, oversized components.