This paper describes the Series 60 heavy-duty diesel engine which is rated from 250 to 400 horsepower (186 to 298 kW). It is an inline, six-cylinder, four-stroke-cycle engine with a front gear train to drive the overhead camshaft, pumps, and engine accessories. The engine is turbocharged and air-to-air charge air cooled and uses four valves with a centrally-located electronic unit injector for each cylinder. The malleable iron piston is of the two-piece crosshead design. The Series 60 engine was designed to set new world class standards in areas of primary importance to heavy-duty engine users, which include fuel economy, reliability, durability, noise level, and exhaust emissions.