The perspective of changing shortly the national policy on emissions from internal combustion engines has lead to research aiming to control emissions without decreasing engine performance. In this research, the influence of several parameters on engine performance was analysed: firing angle, airfuel ratio, mixture preparation and compression ratio 5. A one cylinder CFR engine was used burning hidrated ethanol as fuel. Hydrocarbons and unburned alcohol were :measured separately by introducing into the sampling line a water condenser, and using conventional measuring instruments. Several measurements were carried out to optimize the exaust condition of gases (basically temperature) and using a catalyst to reduce emissions. Finally the measured emissions are shown as a function of several pamaters.