Abstract: A rotor for a rotary engine of the kind comprising a rotor which rotates in a cavity to form working chambers within the cavity which vary in volume as the rotor rotates, the rotor comprising a body having, in a plane transverse to the axis of rotation of the rotor, an outer profile of generally equilateral triangular shape with outwardly curved sides and an inner profile providing part peripheral location formations in regions of the mid-points of the rotor sides in engagement with an insert, the insert providing a bearing part and an indexing gear of the rotor, the inner profile of the body adjacent each apex of the rotor being radially outwards of the inserts of the entire axial length of the rotor thereby providing a gap between the location portions so that axial cooling passages are formed bounded by the rotor body and the insert.