Abstract: Rotary piston type engine comprising a casing having a cavity defined by an inner peripheral wall of trochoidal configuration, a substantially triangular rotor disposed in said cavity for rotation with its apex portions in sliding contact with the inner peripheral wall of the casing to define working chambers of variable volume, a main combustion chamber disposed outside the cavity in the casing and connected with the working chamber in compression stroke, a single fuel injection pump connected through a main fuel injection nozzle to the main combustion chamber and through an auxiliary fuel injection nozzle to the working chamber in intake stroke, and a control valve for allowing fuel to flow through the auxiliary fuel injection nozzle into the working chamber during high load operation of engine.