An engine comprising a first section having a first face and a second section having a second face, the first and second faces being opposed to one another and arranged for relative rotation, the first face comprising at least one chamber, the second face comprising a plurality of discrete regions each being associated with a discrete stage of a combustion cycle, wherein the first and second faces are arranged such that relative rotation thereof causes the at least one chamber of the first face to be exposed to the discrete regions of the second face.