SYMPOSIA PAPER Published: 01 January 1967

Relationship Between Specific Gravity and Other Fuel Properties and Diesel Engine Performance


Although a low fuel consumption is an inherent feature of the diesel engine, operators are always looking for improvement to reduce operating costs. Since fuel is usually bought on a volumetric basis, an obvious way to improve fuel consumption would appear to be to use fuels of high specific gravity. However, the specific gravity of a diesel fuel is not an independent variable, and an increase in specific gravity will probably result in an attendant increase in the mid-boiling point of the fuel and, possibly, a decrease in the cetane number. Also, in general, a fuel of high specific gravity will have high cloud and pour points. It is suggested that for best over-all performance of a diesel engine with respect to cold starting, cold smoking, misfiring, noise and black-smoke emission, a reasonably volatile fuel of moderately high cetane number is required and that these requirements preclude the use of a fuel of high specific gravity. In cold weather, fuels of low cloud point are required although, if careful attention is paid to the designs of a vehicle fuel system, the limit of operability may well be the pour point. The design of the fuel system is particularly important if the full benefit of pour-point-depressant additives is to be realized.

Author Information

Troth, K., A.
“Shell” Research Ltd., Chester, U. K.
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Developed by Committee: D02
Pages: 5–24
DOI: 10.1520/STP46055S
ISBN-EB: 978-0-8031-6758-2
ISBN-13: 978-0-8031-6632-5