Evaluation of Spark Ignition Engine Performance Using Ethanol as Doping Agent on Constant Speed Test

Engine knock is a critical phenomenon engine designers strive to minimize in the world today. Before now, this has made tetra ethyl lead (TEL) an option for minimizing knock. The basic essence of tetra ethyl lead is to enhance octane rating of petrol which is a vital factor to knocking ability. However, the health and environmental challenges associated with the use of tetra ethyl lead propel the desire to replace it with a better environmental and health friendly substance that will at the same time boost octane rating and give a smoother engine operation. Hence, ethanol was considered in this work at a constant speed test of 2000 rpm and compared to leaded petrol as baseline petrol. BSFC of 0.703 kg\kWhr was obtained with 20/80 compared to 0.709 kg\kWhr obtained with 0/100 as baseline fuel. Maximum brake power of 0.74 kW occurred at a bmep of 1.235 bar with 15/85 ethanol/petrol. Similarly, maximum brake thermal efficiency of 13.44% was obtained with 20/80 ethanol/petrol compared to 11.49% obtained with leaded petrol as baseline petrol. It is indicated that maximum power output, low BSFC and low petrol consumption was obtained with 20/80 ethanol/petrol blend. It is convincible that 20/80 blend ratio offer good alternative to other antiknock agents which are associated with harmful consequences to man and environment. The implication of this work is that a definite blend for optimum performance and more environmentally friendly antiknock agent is established.