Abstract: A dual system for overall engine emissions control, including prevention of excessive formation of nitrogen oxides and carbon compounds 1) by cooling and humidifying intake air and 2) by restructuring and modifying hydrocarbon fuels, resulting in a more complete combustion, a significant reduction of the latent heat of combustion and increased combustion potency. The invention utilizes one or more ultrasonic devices to create an aqueous vapor from an ultra-pure water supply, said vapor varying in quantity according to engine size and load, having electronic sensors and controls for precision switching, metering and delivery. Simultaneously, while humidifying the intake air, the hydrocarbon fuel is passed from a fuel supply through a catalytic reactor to restructure the hydrocarbon molecules into a more homogeneous, more combustible and cleaner-burning fuel. Thus equipped, said internal combustion engine can be run as a fuel conserving, low emissions prime mover.