Mixture Maldistribution Due to Manifold Films in a Methanol Fuelled S.I. Engine

Geometric maldistribution is recognized as a major impediment to obtaining maximum efficiency from carbureted or single point injected methanol fuelled engines. In this program engine tests have been conducted with the inlet manifold inclined to provide a gravitational influence on the flow of fuel in order to study maldistribution effects due to manifold fuel films. It was found that substantial distribution errors were caused by this slight gravitational influence, which was only a fraction of that which could occur periodically in a maneuvering passenger car. Improved atomization is shown to be superior to heating the inlet air for reducing maldistribution, although the latter vaporized fuel more completely before the inlet ports. Fuel films may evaporate more easily than airborne droplets in the size range produced by many carburetors.