Four military engines were tested to determine the effect of fuel properties on engine performance. These engines were the Detroit Diesel (DD) 4-53T, Continental Motors LDT-465-1C, Cummins NTC-350, and the Caterpillar 3208T. For this program, 18 fuels were blended to attain wide variations in kinematic viscosity, cetane number, ten-percent boiling point (10%BP), and aromatic content. Each of the eighteen fuels was run at the same relative speed and energy levels in each engine. Loads attained from the given speed-energy points were analyzed using the computer program SAS. These multiple linear regression analyses yielded a stable load prediction equation for each engine with energy, speed, aromatic content, inlet air temperature, kinematic viscosity, and 10%BP as the independent variables. Two additional fuel blends were run as cross-validations. Predicted loads agreed well with observed loads for these fuels except at low speed-energy points in some engines.