An internal combustion gasoline engine includes an air heater coupled to an intake duct of the engine in a heat transfer relationship with air in the intake duct. A combustion pre-chamber is also formed in the head of the engine. The pre-chamber is at least partially separated from the combustion chamber by a wall. One or more apertures are formed through the wall and provide fluid communication paths from the combustion chamber to the pre-chamber, feeding a mixture of air and fuel from the combustion chamber to the pre-chamber. The apertures further define a plurality of combustion paths allowing ignited fuel and air from the pre-chamber to efficiently enter and combust the fuel and air mixture within the combustion chamber. The air heater and the combustion pre-chamber increase combustion efficiency from a first efficiency level to a second efficiency level greater than the first efficiency level.