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In this study experiments were carried out to evaluate performance and exhaust emissions of carbon monoxide (CO) and hydrocarbons (HC) with ethanol-gasoline blends (15E and 85E) and gasoline in a single cylinder, 4-/changing parameters like engine speed, compression ratio, air-fuel ratio and ignition timing were studied in relation to engine performance and exhaust emissions. Effect of intake air temperature on engine performance was also studied. It was found that higher power output and improved energy efficiency were possible with ethanol gasoline blends as compared to gasoline at similar air-fuel ratios. At higher compression ratios engine performance was further improved with ethanol gasoline blends. An extended lean limit was observed which was favorable to obtain lower exhaust emissions.

Methanol (90% methanol + 10% gasoline) when used as a fuel in a 2-stroke spark ignition (SI) engine gave rise to abnormal combustion even at a low compression ratio. The regime of engine operation in which abnormal combustion occurs was identified and the effects of engine parameters such as mixture strength, compression ratio, ignition timing, combustion chamber geometry etc. were studied. Analysis of pressure-time histories of engine cycles when abnormal combustion occurred revealed that abnormal combustion at higher loads is similar to knocking in four-stroke engines. At light loads the nature of abnormal combustion was different. The CFR octane rating of methanol does not correlate with actual anti-knock quality in two-stroke engine combustion. Comparison with primary reference fuels indicated that the two-stroke engine has a very high severity. The hot residual gases seem to have a major role on onset of abnormal combustion.