High pressure direct fuel injection as a solution for performance enhancement in two-stroke spark-ignition engine

Two-stroke spark-ignition engines mainly suffer from the poor fuel economy and high exhaust emission. However, the methodology presented here has adequate potential that can salvage these engines from becoming extinct as the compactness and their power to weight ratio are the two favorable characteristics that provide sufficient leverage for their salvation. The present paper makes an attempt to investigate the influence of the direct fuel injection at moderately high pressure on two-stroke spark-ignition engine performance as well as emission. In this paper, the conventional carbureted two-stroke spark-ignition engine has been modified with a high pressure fuel injection system installed on the cylinder head. The injection of fuel is timed with the closure of exhaust port shut by the piston, which helps in saving fresh fuel from getting short-circuited through the exhaust port. The experimental investigation has been carried out on the engine at various throttle positions of both carburetor as well as fuel injector for different speeds. The experimental measurements revealed that results of direct fuel injection mode compared well as opposed to the carburetor mode. It was observed that brake power exhibited significant improvement approximately 20.1% as compared to the conventional engine. The brake thermal efficiency is found to be 16.3% higher than that of the conventional engine. Above all, fuel loss through short-circuiting noted to have reduced brake specific fuel consumption by 17%. The direct injection system has shown 27.5 and 88.5% reduction in carbon monoxide and unburned hydrocarbons emission, respectively, as compared to the conventional engine.