An experimental study of the performance and emissions of spark ignition gasoline engine

The resistance of gasoline to knocking is critically determined by the octane number. The engine will encounter a significant waste of power, reduced efficiency and enhanced emission levels if a well-defined gasoline octane number is not employed. In this study, the engine performance and emission of hazardous gases were experimentally investigated through the use of three gasoline fuels (RON95, 97 and 102). The engine selected for the testing was a 1.6-L four-cylinder Toyota 4A-GE Blacktop VVT with the original ECU. The engine was run at different constants for various part load conditions as well as at constant throttle body. The engine that was operated with RON97 fuel was found to display positive improvements in terms of the brake specific fuel consumption of the engine, reduced at an average of 5 and 10%, compared to RON102 and RON95 fuels, respectively. Furthermore, the engine operated with RON102 fuel exhibited higher torque and engine power compared to RON97 and RON95. The brake thermal efficiency for both RON97 and RON102 fuels was remarkably improved at an average of 12% compared to RON95. The incorporation of RON102 fuel reduced the emission of NOX compared to RON95 and RON97 fuels at an average of 34% and 40%, respectively. The RON102 fuel produced the highest HC emission compared to RON97 and RON95. The CO emission was found to be higher for RON102 fuel compared to RON97 and RON95 at an average of 12.4% and 17%, respectively. The study concluded that although engine performance and efficiency versus gasoline depend highly on the engine design parameters, RON97 is able to deliver high performance and efficiency in all conditions. Therefore, it is recommended that RON97 be used instead of RON95 to achieve better performance with this type of engine.