Influence of the compression ratio and ignition timing on Sinjai engine performance with 50% bioethanol-gasoline blended fuel

Influence of the compression ratio and injection timing on Sinjai engine performance with 50% bioethanolgasoline blended fuel were investigated on water brake dynamometer. The properties of bioethanol were measured based on American Society for Testing Materials (ASTM) standards. Fuel consumption was measured by the time of fuel consumption per 25 cc of fuel in a measuring glass, whereas combustion air consumption was measured using an air flow meter. The emission parameters, exhaust gas temperature and air fuel ratio were measured using STARGAS exhaust gas analyzer. The compression ratio was increased from 9, 6; 10, 6 to11, 6 dan ignition timing was set for minimum advanced of spark ignition for best torque, MBT with limited by knocking. Ignition timing was adjusted for maximum torque and thermal efficiency. Engine performance testing conducted in a variable speed, starting the engine speed 2000 to 5000 rpm with intervals of an increase of 500 rpm. The engine performance parameters evaluated were torque, brake mean effective pressure, power, specific fuel consumption, thermal efficiency, exhaust gas composition and volumetric efficiency. The results showed that the increase of compression ratios improved engine performance for 50% bioethanol-gasoline blended (E50) fuel throughout all the speed range investigated. The both fuel fuel has same the tendency that the degree of the ignition timing is more advanced due to higher engine speed but the value of degree of ignition timing advanced, from 18 0BTDC at engine speed 2000 rpm until 26 0BTDC at engine speed 5000 rpm. The addition of compression ratio requiring retarded ignition timing to avoid detonation. The use of E50 fuel, at the compression ratio is 11.6 can improve brake torque, power and mep respectively by 3, 68%, 4.58% and 3.68% as compared to using pure gasoline at a compression ratio of 9, 6. While the influence of adding compression ratio at the E50 can reduce bsfc by 13, 42 % and increase thermal efficiency by 14, 67 %.