The Stirling Engine is an External Combustion Engine (the heat source is outside the engine) and can use any available source of adequate heat or cold. It is a classic illustration of converting heat energy into mechanical work using a thermodynamic cycle similar to the well-known Carnot cycle. The Manson cycle Sterling Engine uses a large single cylinder rather than dual cylinders. It is very similar to a 2-stroke engine found in many small vehicles. All Sterling engines are tested before shipping.