DUAL-MODE ENGINE WITH CONTROLLED AUTO-IGNITION

An internal combustion engine is described having exhaust and intake poppet valves having opening and closing events relative to the rotation of the engine crankshaft that are selectable such that the engine may be switched between a two-stroke mode and a four-stroke mode, wherein control means are provided to operate the engine in four-stroke mode under high load and starting operating conditions and in a two-stroke controlled auto-ignition mode under low and medium load operating conditions.