A rotor for an electrical generator is disclosed, including a rotor body having a circular portion and a cylindrical portion coaxial with the circular portion. A generally cylindrical recess is defined by the cylindrical portion and the first side of the circular portion for receiving a stator. At least one first wall is at least partially spaced apart from the first side of the circular portion, defining at least one chamber therebetween. The chamber has an inlet. An aperture in the at least one first wall defines an outlet of the at least one chamber. At least one second wall extends outwardly from the first side of the circular portion. The at least one second wall has an end portion adjacent to the inlet of the at least one chamber. An internal combustion engine with an electrical generator and a method of cooling an electrical generator are also disclosed.