Abstract
A 11L heavy duty LPG MPI engine has been developed using the liquid phase LPG injection system which is one of the next generation LPG fueling technologies, since the LPG MPI engine can achieve higher power and efficiency, and lower exhaust emissions than the conventional mixer type system. A prototype natural aspiration(NA) type engine was firstly developed in this work prior to a turbo-charged engine due to less difficulty in technical approach. The performance results demonstrated that the LPG MPI engine has the higher engine maximum power and torque by approximately 20% than the base diesel engine. The high torque of the engine in low rpm ranges satisfied an important design parameter for heavy-duty vehicles. And, EURO III regulation for exhaust emissions was successfully met up to 25% of its level.