In this study, which is a continuation of an earlier one, the performance and emissions of an uncooled 2.0-L single-cylinder open-chamber diesel engine were experimentally investigated further. In addition to the routine performance and emissions measurements, the heat-release characteristics, friction losses, and temperatures of combustion-chamber components were measured. The performance of the uncooled engine, which was significantly better than that in the earlier study, was as good as the performance of the water-cooled engine with the exception of high-load/low-speed conditions.For a given fuel-input energy, the uncooled engine had lower friction losses and lower pumping losses but also generally had lower thermal efficiency. The uncooled engine appeared to have less premixed combustion and substantially shorter heat-release duration than the water-cooled engine. As expected, the nitric oxide emissions from the uncooled engine were higher than those from the water-cooled engine, but the hydrocarbon emissions were lower. The uncooled engine emitted more smoke at the high-load/low-speed conditions.