Butanol is deemed as a potential alternative fuel for vehicle, but there are few studies about applying butanol in engine combustion. This paper focuses on application of butanol-gasoline blend fuel on scooter engine. In this research, different volume percentage of butanol-gasoline blend fuel, B10, B20, B40, B60, B80 and B100 are applied on 125cc scooter engine to conduct engine experiment, and higher than B60 blend fuel is declared as high butanol concentration blend fuel. The test conditions are set at 4000 and 6000rpm under partial load and full load. After executing engine experiment, engine performance, brake specific fuel consumption (BSFC), emissions and combustion analysis are discussed. Furthermore, viscosity and fuel spray are tested with high butanol concentration blend fuel.
The engine experimental result shows that B100 fuels can increase engine performance under engine 4000 and 6000rpm. In addition, B10 and B20 fuels can improve not only BSFC but also emissions under stoichiometric air-fuel ratio. However, engine runs unsteadily due to high butanol concentration blend fuel, which might be caused by bad spray atomization due to high viscosity under ambient temperature. Under LBT (Leanest mixture for Best Torque) condition, engine operates more steadily with smaller coefficient of variation of indicated mean effective pressure (COV of IMEP) than gasoline. Especially for high butanol concentration blend fuel, lower COV of IMEP, shorter ignition delay, and shorter burn duration can be realized.