Characteristics of Diesel Fuels Influencing Power and Economy

OF the many characteristics of diesel fuels, heating value, ignition quality, and possibly fuel viscosity are the only important ones affecting engine power and economy, the authors disclose. In their paper they present data obtained from an extended fuel research program concerning the power and fuel economy obtained when using fuels differing in their physical and chemical characteristics.

The points which seem to the authors to be of greatest practical significance are summarized as follows:

1. 1.
   Assuming complete combustion, fuel volatility affects the pints per brake horsepower-hour only indirectly as it is related to heating value and ignition quality.
2. 2.
   Most present-day engines have fixed injection timing and, on such engines, ignition quality is a major factor in determining volumetric fuel economy in the upper speed ranges. At the lower engine speeds, heating value in terms of Btu per gal, or as estimated from API gravity, is the most important consideration.
3. 3.
   Fuel viscosity by itself is not an important factor in the power obtained on a high-speed diesel engine, except in instances where worn injection equipment may make it undesirable to use a low-viscosity fuel.