The invented engine comprises a working cylinder with a piston, pre-ignition chamber with spark plug and a combustion chamber which is cylindrical in shape, a fuel-air mixture injector, which is a compressor cylinder with a piston and fuel delivery device and channels for supplying the fuel and air into the combustion chamber. It also has channels for injection of the fuel-air mixture into the combustion chamber. There is a check valve between the fuel supply channel and the compressor cylinder. The pre-ignition chamber has the shape of a cup or flattened cone. The diameter of the base of the pre-ignition chamber equals the diameter of the combustion chamber. The engine has one or more pairs of channels for delivering the fuel-air mixture to the combustion chamber. The axes of these channels are paired and angled towards each other. The angle between the axes of these channels and the axis of the combustion chamber is selected within the interval between the crossing point of the axes of these channels on the central electrode of the ignition plug and the crossing point of the axis of the combustion chamber with the bottom of the working piston in its top dead point position. The invention provides for improving operation stability of the engine, reducing fuel consumption rate and reducing the toxicity of the exhaust gases by increasing homogeneity of the fuel-air mixture.