Engines having cylinders of noncircular cross section wherein the cylindrical curve is generated at a preselected constant outwardly normal distance from a closed curve. The closed curve about which the cylinder curve is generated is preferred such that there is a continuous change of curvature without discontinuity in that curvature in the cylindrical curve, symmetry of two inter-vertical axes. A plurality of intake and exhaust port arrangements are disclosed illustrating four intake ports and four exhaust ports on opposite sides of the major axis of symmetry of the defined cylinder. The outermost of the ports are smaller and are positioned closer to the top of the cylinder. The valves are oriented such that the stems thereof point to the centerline of the associated camshaft for direct actuation. |