Abstract: Operation of a homogeneous charge compression ignition engine is adapted to fuel variations. A variable valve actuating system is employed to effect conditions conducive to homogeneous charge compression ignition operation. Nominal valve timing is selected and adjustments thereto are made based on deviations in combustion phasing from a desired combustion phasing. Fuel delivery timing and quantity are adjusted once valve timing authority limits are reached to achieve further combustion phasing improvement.

Abstract: A vehicle driven by a homogeneous-charge compression ignition (HCCI) engine includes a fuel supply that supplies a hydrocarbon fuel in a first amount and an acetylene supply that supplies an acetylene-based component in a second amount. A cylinder has a piston reciprocally driven therein. The cylinder receives a combustion mixture including a third amount of air, the first amount of hydrocarbon fuel and the second amount of the acetylene-based component. The piston compresses the combustion mixture to induce auto-ignition of the combustion mixture. The acetylene-based component includes one of acetylene, an acetylene-hydrogen mixture, and a mixture of acetylene, hydrogen and other products of the acetylene production process.