IMPROVEMENT in the control of smoke in the automotive diesel engine can be brought about by the use of lighter fuels of suitable ignition quality in cases where either design, maintenance, or adjustment fail to accomplish the degree of smoke control desired, the authors conclude. But this control is accomplished by some reduction in power and a loss in fuel economy. They suggest taking the power loss required for smoke control by means of resetting the smoke stop adjustment while retaining the advantage from an economy standpoint of the higher Btu per gal of the heavier fuel.
The satisfactory performance of the heavier fuels in European bus operation clearly shows that smoke control can be effected by other means than resorting to fuels approaching kerosene in volatility.
Another finding reported is that the effect of cetane number on smoke is less important than the effect of volatility, except in cases where the ignition of the fuel is below the minimum demanded by considerations of roughness and cold starting.
The study reported in this paper not only covers the relationship between fuel properties and smoking, but also includes work on the effect of engine design, mechanical condition, and adjustment of the equipment on smoking. Not included in the program are other problems associated with smoking and objectionable exhausts from diesels, such as the related questions of odor, lubricating oil, and operating temperature.