Abstract: Device, systems and methods for introducing water into the combustion chamber of an internal combustion engine, incorporating an injector and a heater, are shown and described. The injector is configured to inject water at a pulse rate and frequency controlled by various engine performance readings, and the heater configured to convert the water into steam on demand, and to route the steam into the air stream flowing toward the combustion cylinder. In certain embodiments, the heater is positioned to provide steam to the cylinder before the temperature of the steam changes significantly. In other embodiments, the heater is configured to convert to steam a flow of water equal to or less than the amount of fuel burned by the engine during the same time period.