A diesel engine is designed to burn on a mixture of liquid fuel or diesel, and liquefied petroleum gas, or gas. The diesel is injected into the cylinders as is conventional on diesel engines. The gas is mixed into the intake air. The output of the governor connects to a diesel control and a gas control. As more fuel is consumed, both the amount of diesel and the amount of gas is increased; however, the amount of gas is increased at a much faster rate than the amount of diesel is increased. At no load, the engine operates on about 76 percent diesel and 24 percent gas. At 100 percent load, the engine operates on about 80 percent gas and 20 percent diesel. A special gas valve is used.