Exhaust Hydrocarbon and Nitrogen Oxide Concentrations with an Ethyl Alcohol-Gasoline Fuel 640651

The exhaust hydrocarbon and nitrogen oxide concentrations of a single-cylinder engine, operating on a 25% (wt.) ethyl alcohol – 75% gasoline fuel, are compared to those operating on gasoline. For comparisons at the same airfuel ratio but lower than 15.3, the addition of ethyl alcohol to gasoline reduces the exhaust hydrocarbon concentrations and increases the nitrogen oxide concentrations. At the same air-fuel ratio but higher than 15.3, the addition of ethyl alcohol reduces both the hydrocarbon and nitrogen oxide concentrations. However, tests with automobiles, operating at the same air-fuel ratio with both fuels, indicate that the addition of ethyl alcohol causes an increase in “surge” and, in some cases, results in a power loss. To overcome these performance problems, the ethyl alcohol-gasoline fuel should be operated at about the same percent theoretical air as gasoline. For comparisons at the same per cent theoretical air, the addition of ethyl alcohol to gasoline has little effect on the exhaust hydrocarbon and nitrogen oxide concentrations. On this basis, addition of ethyl alcohol to gasoline appears to have no practical advantage from the standpoint of reducing automobile exhaust hydrocarbon and nitrogen oxide concentrations.