The B Series product line consists of 3, 4 and 6-cylinder high swirl direct injection diesel engines having a displacement of .98 liters per cylinder. They were designed to achieve high levels of turbocharging with conservative component loading. The seven most important design objectives were durability, reliability, sociability, performance, application adaptability, cost and service. The design concepts employed are discussed in some detail and results are given for typical analyses performed during the design phase. Optimized engine performance data is presented for emission regulated and non-emission regulated configurations. The mechanical development and validation of the design are also discussed along with the accompanying results. This development and validation process included rig tests, fatigue tests, endurance tests, abuse tests, field tests and reliability proof tests. Some typical approaches to cost avoidance are enumerated towards the end of the paper.