Abstract: There is disclosed an engine which drives a turbine via a series of relatively identical hot gas pulses. The series of pulses are generated by a combustor-compressor unit under a controllable firing rate. The firing rate of the unit is rapidly variable over a wide range to enable one to drive the turbine and a shaft coupled to the turbine for propelling a vehicle. The combuster compressor is controlled to develop the gas pulses by a servo system which monitors the shaft rotation for varying mechanical loads to operate the turbine at a constant speed. A torque converter is employed to transform the shaft power into mechanical power necessary to propel a vehicle at conventional and required speed variations.