... was increased from 8.5:1 to 15:1 at 8 N-m load. The emission level of carbon dioxide was decreased with an increase in CR due to an improvement in the thermal efficiency and the combustion process. spark-ignition engine biogas compression ratio variation operational limits pre-ignition cycle-to-cycle...

... effective pressure (IMEP)) and high (limited by pre-ignition) operating loads were decreased; however, it was found that the overall operating range was increased. Results also showed that for a given operating load, with the increase of CO 2 percentage in the fuel, the brake thermal efficiency...