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In this research, with proposed design of hydraulic-controlled variable valve lift system, a feed pump is used to supply the low-pressure oil into the hydraulic pump which will compress low-pressure oil as high-pressure oil and pumps the high-pressure oil into the hydraulic cylinder. In the meanwhile, the intake valve opened in accordance with the plunger is pushed by the hydraulic cylinder. To achieve the change of intake valve lift, a DC motor connected with the control rack that is used for controlling oil-drain time of the hydraulic pump. In addition, a solenoid valve is installed in order that the intake valve will be closed quickly without controlling the drain flow when the maximum valve lift is reached. Commonly, the throttle is not required with variable valve lift system, but the throttle is kept for engine start. Hence, except for engine cranking condition, the throttle maintains in wide open (WOT) under different test conditions.

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.