The current engine manufacturers are inclined to develop engine with higher compression ratio to increase its efficiency in accordance with the availability of gasoline in the market. Meanwhile, gasoline fuels distributed in Indonesia have research octane number (RON) between 88 to 98, i.e., gasoline 88, gasoline 92, and gasoline 98. In order to increase the octane number of gasoline, an ethanol-gasoline blend can be one of the alternatives since ethanol has higher octane number than gasoline. Nevertheless, gasoline blended with ethanol will reduce the heating value of the fuel mixture. Due to many choices of gasoline and various octane ratings available in the market, prices become the main consideration to buy specific gasoline instead of considering octane number. The objective of this research is to analyze the influence of ethanol-gasoline blend (E5) with various octane ratings on the performance of 150cc, single cylinder, four-stroke gasoline engine, with fix compression ratio. The tests were carried out using AVL dyno for engine testing which performed at maximum load (wide open throttle) and diverse engine speeds of 1000, 1500, and 2000 rpm. For each engine speed variation, we measured the engine power, torque, air-fuel ratio (AFR) and specific fuel consumption (SFC). The results indicated that in general, a higher octane number of ethanol-gasoline blend (E5) will give benefits in the form of an increase of engine power and torque, and a decrease in the value of SFC.