PURPOSE: To obtain a small size pollution-free engine with large output by a method wherein hydrogen gas or the like is sucked in through a venturi, which is shielded from the outside air, during the suction stroke and at the same time atomized moisture is also mixed therewith to be compressed as a whole and then liquid oxygen is injected into said gas moisture mixture at the final stage of the compression stroke in order to ignite the mixture.

CONSTITUTION: Moisture is sucked out of the tip of a venturi in a sprayed form by passing hydrogen gas, the pressure of which is equal to the atmospheric pressure, through the venturi, which is shielded against the outside air, during the suction stroke of a piston in order to mix with said hydrogen gas and then to supply to a cylinder during the operation of an engine. After that, the hydrogen gas mixed with moisture is compressed. Liquid oxygen is injected under high pressure over a period ranging from about 8° before the end of the compression stroke to 30° or more after the start of the combustion stroke of the piston in order to strongly promote the combustion stroke. In this case, said moisture turns to be superheated steam, resulting in generating much larger output.