Comparison of Characteristics Between Gasoline and Methanol in a Spark Ignition Engine

An experimental study on performance, exhaust emissions and cyclic variations was carried out for gasoline, M100 and M85. To take the advantage of methanol's higher octane number, increased compression ratio was tried and its effect was investigated. A pre-ignition detector was installed to eliminate the possibility of pre-ignition damage. THC emissions from methanol were corrected by some assumptions in order to be compared with those from gasoline.

Combustion pressure data were measured by virtue of a fast data acquisition system. From them, all data required for the investigation of cyclic variability were obtained. The coefficient of variations of 1MEP was applied as a criterion of lean misfire limit.

Improved performance was achieved for methanol. The advantage on exhaust emissions, especially NOx and THC, was also confirmed. It was found that Pmax has close relationship with combustion durations and there is no noticeable connection between successive cycles.