This paper discusses the philosophy behind and design features of a new family of high-speed 2-stroke cycle diesels of 270-860 hp, some of the mechanical and performance problems encountered during their development, and some of the test methods used and the results obtained. The good power-to-weight ratios and growth potential of these 92 in3 (1508 cm3) per cylinder engines make them strong contenders as highway truck, industrial, earthmover, and marine prime movers.