Evaluation of Performance and Emission of SI Engine Fuelled with CNG at Low and High Load Condition

An experimental study was conducted to evaluate the performance and emission of spark ignition (SI) engine fuelled with CNG at low and high load condition. This study is the series activity of research, design and development of conversion kit for gas fuelled vehicle in the author laboratory. The SI engine that used in this study is Honda L15A, four cylinders, 1,497 cm3 using electronic control unit. Three different fuel system namely standard gasoline fuel system, commercially CNG conversion kit and proposed CNG conversion kit designed by Research Centre for Electrical Power and Mechatronics–Indonesian Institute of Sciences, all of them utilized with fuel injection system and electronic control unit were used in this study. The test was conducted on the 25% and 80% throttle opening position with engine speed over 4,800 rpm. The results show that the maximum brake power at 25% throttle opening position of SI engine using commercially CNG conversion kit (19.00 kW) is almost same with SI engine using proposed CNG conversion kit (19.68 kW), while for 80% throttle opening position the maximum brake power of SI engine using proposed CNG conversion kit (38.67 kW) is higher than commercially CNG conversion kit (34.29 kW). The emission of CO and HC at 80% throttle opening position is lower than at 25% throttle opening position for both of SI engine using commercially and proposed CNG conversion kit.