As competent and low-pollution alternative fuel, CNG has revealed its excellence over engine performance and emissions. In recent years, CNG is considered as the diesel engine alternative fuel for heavy-duty engine applications due to its lower emissions and cost effective after-treatment systems. Due to the implementation of stricter emission norms over the years, the evolution of the fuel supply system has become more robust and electronically controlled.
In the case of CNG engines, most of the engines were equipped with MPFI fuel system, for its precise fuel control abilities and controlling emission parameters. However, this MPFI system encompasses severe design changes in the intake manifold and is cost worthy to OEMs over the SPFI fuel system. MPFI system adds on the overall cost of the engine unit and its maintenance when compared to SPFI system. SPFI fuel system had proved its robustness to achieve BSIV emission norms but, due to challenging test methods and stringent emission limits, BSVI development with this fuel system seems cumbersome with limited control parameters. This paper presents the research work conducted on a heavy-duty CNG engine with a SPFI fuel system. The challenges involved for achieving the BSVI emissions through engine calibration, without major engine hardware change along with engine performance is incorporated in this work.
