The modification and testing of a compression ignition engine using diesel and vapourized ethanol as fuel has been carried out. Tests on the engine fuelled with diesel only were made, and the performance evaluated to form a basis for comparison for those of ethanol-diesel dual fuelling. Modifications were made in the introduction of the ethanol and air. A carburettor was used to vapourize aqueous ethanol into the engine. The effect of preheating the intake ethanol-air mixture was also investigated. Performance was evaluated in terms of engine horsepower, brake specific fuel consumption, brake thermal efficiency, the exhaust gas temperature, lubricating oil temperature and exhaust emissions. The vapourized ethanol partially reduced diesel fuel consumption but also increased total fuel delivery. Vapourization increased power output, thermal efficiency and exhaust emissions but lowered exhaust temperature and lubricating oil temperatures.