University of Arkansas, Fayetteville Division of Agriculture


This study compared the performance, fuel efficiency, and exhaust emissions of a 2.61 kW engine fueled with regular unleaded gasoline (87 octane) and an 85% ethanol blend (E85) under two load conditions. Four 1-h tests were conducted with each fuel at both governor’s maximum (3400 rpm) and peak torque (2800 rpm) conditions for a total of 16 tests. At governor’s maximum engine speed, there were no significant differences (p>0.05) between fuels for engine torque, power, specific carbon dioxide (sCO2 ), specific carbon monoxide (sCO), specific hydrocarbons (sHC), or specific oxides of nitrogen (sNOX) emissions. However, there was a significant difference in specific fuel consumption and specific dioxide (sO2 ) emissions with E85 requiring the consumption of more fuel and emitting fewer oxide gases. Under peak-torque test conditions, there were significant differences by fuel for power, torque, and specific fuel consumption, as ethanol required more fuel while developing less power and torque when compared to gasoline. There were no significant differences by fuel type in sCO2 , sCO, sHC, sO2 , or sNOX emissions. The results indicate that performance was similar when the engine was fueled by regular unleaded gasoline or E85 under rated engine-speed conditions; however, the ethanol-fueled engine produced significantly less power and torque under peak torque testing conditions. In both testing conditions, specific fuel consumption was significantly higher with E85.