An 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 the higher power and efficiency, and lower exhaust emissions than the conventional mixer type system.
Two prototypes - a natural aspiration(NA) engine and a turbocharged inter-cooler(TCI) engine - were developed in this work and tested to measure the performance and emissions. For a NA type engine, in order to achieve the low emissions, the stoichiometric air/fuel ratio was adapted with a three-way catalytic converter. Whereas, for a TCI type, the lean burn technology was introduced to minimize the thermal loading due to an increase of the engine power.
The results in this work demonstrated that the LPG MPI engines have the higher engine performance and lower exhaust emissions than the base diesel engine. Especially, with the NA stoichiometric engine, EURO III regulation was successfully met up to 25% of its level.