The Effects of Methanol Injection on Emission and Performance in a Carbureted SI Engine

A single cylinder carburetor SI engine with a modified L type cylinder head and equipped with a fuel injector was used to inject methanol into the combustion chamber.

Four series of runs at an engine speed of 2500 rpm were made. One series with different values of λ* was performed with gasoline, and the other three series methanol was injected into the gasoline-air mixture. Each series of methanol injected run was supplied with the same energy input per cycle to correspond to that of the gasoline.

The results of the experiments indicated that the performance (BHP) of the engine was proportional to the energy input of the mixture up to about 50% methanol injected.

With the equivalence air-fuel ratio above λ = 1.15 (lean mixture), it was found the NO_x concentration decreased more than 30% while the BSFC remained constant.