TESTS on two series of diesel engines were run. The first group, consisting of four engines, had the stroke changed only, while the second group had the stroke/bore ratio changed and the displacement held constant.
Results of the tests indicate that the longer stroke engines had more power, higher torque, and lower fuel consumption.
Friction was high for the short-stroke engines at low speeds and for the longest stroke engine at high speeds. Theoretical analysis indicates that the optimum stroke/bore ratio for best performance may vary as the compression ratio and bore diameter are changed.