THE INFLUENCE OF DIFFERENT COMPRESSION RATIOS ON THE PERFORMANCE OF AN CNG-FUELLED FLEX INTERNAL COMBUSTION ENGINE

In Brazil, in the last few years, there has been a tendency to the use of alternative fuels. One of them is Compressed Natural Gas (CNG) and it is used due to its low cost, low fuel consumption and available technology. An originally gasoline or alcohol fuel engine can be also fuelled by CNG with some modifications, turning it into a multi-fuel engine. Commonly, however, the original compression ratio is unchanged, not allowing to explore CNG higher resistance to knock. This work aims at obtaining and analyzing the 1.3-L 8v FIRE FLEX engine performance curves for different compression ratios. A 5^th generation BRC CNG multi-point fuel injection system is used for 11:1, 12,5:1 and 15:1 compression ratios and a development engine control unit and its calibration software were used to perform the system electronic management.