Abstract: A mixed cycle engine has a divided combustion chamber including a turbulence prechamber in which fuel is mixed with air and burned upon injection at compression ratios preferably between those of conventional diesel and gasoline engines. To provide positive ignition of the injected fuel, a small antechamber is provided which contains a spark plug and the fuel injection nozzle and is connected to the prechamber by an orifice through which the nozzle is arranged to direct the charge of fuel into the prechamber. The orifice is sized so that air flow passing from the prechamber to the antechamber near the end of the compression stroke peels off some of the fuel at the beginning of injection and carries it into the antechamber, forming a combustible mixture which is easily ignited by the spark plug in the relatively quiescent antechamber.