Combustion, Friction and Fuel Tolerance improvements for the IDI Diesel Engine

Fuel economy, emission and power capability of IDI Diesel engines were defined from mapping surveys of 12 production engines. Improved fuel economy, lower emissions and increased tolerance for lower quality fuels were obtained from reductions in friction and modifications to the combustion system. A 16% reduction in friction obtained with low tension piston rings, low friction coating on the piston skirt and roller followers provided an 8% reduction in fuel consumption. Combustion system modifications consisting of a smaller throat prechamber and an air cell provided 26% and 41% reductions in particulates, respectively. Reductions in cetane number from 47.5 to 32.5 resulted in a 31% increase in particulates, but addition of a cetane improver reduced the increase to only 4%. Both combustion system modifications, when operated on 32.5 cetane fuel without the cetane improver, provided lower particulates relative to the baseline combustion system operated on 47.5 cetane fuel.