Abstract: The present invention provides an internal combustion engine comprising a main body portion defining a combustion chamber in the form of a toroidal cavity with a generally circular axis, an air intake, compressor means for drawing air from said intake and delivering it to said toroidal cavity under pressure in a generally tangential direction to impart a swirl motion to gases in said cavity about said circular axis, means for exhausting combustion gases from said cavity, drive means disposed adjacent said exhaust means so as to be acted on by said combustion gases to perform mechanical work and thereby provide an output of the engine, and means coupling said drive means to said compressor means for providing power thereto.