Kiyotaka Nakamura

The Development of Driveability Index and the Effects of Gasoline Volatility on Engine Performance

To reduce engine exhaust emissions, the authors have had to deal with this global environmental problem from the fuel side by introducing oxygenated fuels, reducing the RVP and using low aromatics. But when the fuel components and distillation are changed the engine driveability must be considered. T50, %90, RVP and so on have been used as the fuel index up to the present. It is possible to characterize the fuel from one aspect, but these indexes don`t always represent the real feature of the fuel. In this paper the authors propose a New Driveability Index (NDI) that is more realistic and accurate than the other fuel indexes for a 1,600cc DOHC L4 MPI type engine. The authors used Model Gasolines and Market Gasolines and tested them according to the Excess Air Ratio Response Test Method that was suggested in SAE paper {number_sign}930375, and calculated the NDI statistically. This NDI is a function of the fuel distillation. NDI is suitable for using with not only hydrocarbon gasolines but also oxygenated gasolines such as those mixed with MTBE, ETBE and Ethanol. They tested two other engine types and confirmed that they could apply this NDI to them.