A new heavy duty diesel truck engine, the 3306 DITA, has been developed by Caterpillar Tractor Co. The engine is an Inline 6 cylinder covering the 245-270 hp (182-201 kW) range. A primary objective of the development program was a 7-10% reduction in fuel consumption while maintaining the durability, reliability, and serviceability required of a heavy duty truck engine. Manufacturing considerations for high volume tooling were emphasized during the design stage. This paper deals with the design, development and performance aspects of the engine.