FUEL QUALITY OR ENGINE DESIGN: WHICH CONTROLS DIESEL EMISSIONS?

Federal standards on diesel exhaust smoke are currently in force and standards on carbon monoxide, oxides of nitrogen and hydrocarbon emissions for the 1974 model year were issued recently by EPA. Except for smoke, relatively little information is available on the relation of fuel quality to emissions from diesel engines, but control of diesel emissions via fuel has been suggested by users, control agencies and public interest groups. To provide information on effects of fuel quality, we measured emissions from three diverse engines with fuels that exceeded the commercial range in quality of No. 1 and 2 diesel fuels. We found that fuel properties have measurable effects on emissions, but the effects are much smaller than those of engine design and operating conditions. We conclude that changing fuel quality does not represent an effective way to control emissions from today's diesel engines.