Motors and associated methods. Representative motors include high-conversion efficiency, unidirectional or bidirectional small-scale hot gas vane motors. An injection chamber receives hot injection gases. A non-circular stator is coupled to the injection chamber, and the non-circular stator is designed for maximum expansion of the hot injection gas. A rotor is coupled to the non-circular stator and accelerates when the hot injection gas expands, resulting in a conversion of hot injection gas to rotary mechanical power.