Abstract: The present invention relates to turbine motors which make use of combustion gas to turn a turbine wheel. The motors make use of a reaction tunnel consisting of a casing having a central chamber with a turbine wheel rotatably mounted therein. The central chamber is provided with openings along two opposing side walls such that combustion gas may circulate in a corkscrew-like fashion through the reaction tunnel via exterior gas conduits which link holes on the opposing side walls of the chamber. Incoming air is preheated by being brought into contact with the exterior gas conduits so that the air may undergo indirect heat exchange with combustion gas, the preheated air then being fed to the air inlet of a combustion chamber. The motors of the present invention thus make use of heat which would otherwise be lost.