Performance and Emissions of a DDC 8V-71 Transit Bus Engine Using Ignition-Improved Methanol and Ethanol 912356

A 1979 8V-71 model DDC two-stroke diesel transit bus engine was tested using ignition-improved methanol and ethanol. The testing was conducted using the Environmental Protection Agency heavy duty engine transient test procedure. The methanol and ethanol fuels were found to have very similar combustion characteristics and required the same percentage of ignition improver (7.5 volume percent) to obtain similar peak cylinder pressures and rates of pressure rise as were observed using diesel fuel. Emissions increased rapidly as the percentage of ignition improver was reduced below the optimum determined. Ignition-improved methanol and ethanol can greatly reduce fuel-produced particulate emissions with the trade-off of a small increase in total unburned fuel emissions. Carbon monoxide emissions were found to be dependent on stoichiometry only and not fuel type. Based on this test work, it appears that diesel engines retrofitted to use ignition-improved alcohols in conjunction with an oxidation catalyst could reduce all gaseous emissions and particulates relative to the use of diesel fuel.