The uses of engine-driven machines are increased and the air is polluted day by day. Thereby, substitution of natural gas (made by the country) in Petroleum would save more money (foreign currency spending), reduce air pollution and much more good benefits could be achieved. However, natural gas- driven engine could produce lesser power output in comparison with petroleum –driven engine. This problem can be solved by setting up the supercharger at the engine inlet that helped the engine to produce higher output, but reduce the air pollution. The comparison of performance of the petrol engine using the fuel of petrol and CNG as alternative fuel with and without supercharger are presented in this paper.