Abstract: Water is sprayed onto the surface of a bank of conduits or tubes extending through a heat exchange compartment, which conduits carry the hot exhaust gases from a diesel engine at a temperature of approximately 950.degree.-1100.degree. F. The water is sprayed at such a rate that a substantial portion of the water is reformed into a mixture of hydrogen and oxygen gas and steam. The hydrogen is then mixed with air to form hydrogen enriched air which is introduced into the combustion chamber. When the hydrogen enriched air is compressed, the diesel fuel is introduced with a resulting improvement in fuel efficiency and maximized combustion of the fuel. The water is delivered to the hydrogen generator responsive to the activation of the accelerator pedal at a controlled rate in which the percentage of water to diesel fuel is substantially in the range of 5% to 10%. Air from the engine turbosupercharger is delivered to the hydrogen generator to pick up and carry the hydrogen gas back to the air intake of the engine.