The Influence of Fuel Characteristics on Vaporization in the S.I. Engine Cylinder During Cranking at Low Temperature

Using five single-component, three dual-component and five full boiling range fuels, the relationship between engine startability under low temperature and fuel volatility was experimentally studied. The study was carried out through the analysis of fuel vaporization and mixture formation in the cylinder. The effect of other factors such as cranking speed, ignition timing and fuel quantity supplied to the cylinder on startability was also examined from the view point of fuel vaporization in the cylinder. A theoretical approach for estimating the startability with fuels of various volatility was attempted. Based on this estimation, the degree of cold startability deterioration with lower volatility fuels and the way to improve cold engine startability were discussed.