Fuel for American Oil-engined Vehicles
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Highspots of a Paper Dealing with the Application of Ignition Accelerators to High speed engine Fuels
AT the present time there arc in the U.S.A. some 10,000 commercial vehicles with oil engines. On top of this number the army authorities of that country are fitting similar power units in many lorries and tractors, whilst radial, air-cooled oil engines are being used in an increasing number of armoured fighting vehicles. ,So far as the army is concerned, the call is for fuel to a specification which stipulates a minimum cetane number of 50.
At present, some 26 per cent! of the straight-run fuels produced from American crudes are belovi the 50cetane rating. To make good the deficiency, recourse may be had to solvents, refining, hydrogenation, or blending with high-cetane stock. The cost of these practices may be tolerable under war co,nditions, but when normal commercial circumstances have to be faced, the cost may prove prohibitive. Some of the American oil-engine manufacturers estimate that the appeal of the compression-ignition engine would be overridden if there were an oil-fuel price increase of 12 per cent. Present-day conditions emphasize the iinportance of a single-fuel standard, tr,S.A. Government requirements are to only a trifling degree more exacting than technical authorities recommend for engines in civilian practice.
A short paper by Mr. J. S. Bogen, presented to the Society, of Automotive Engineers in January, deals briefly with the application of ignition
accelerators to high-speed-engine fuels. In graph and tabular form there is a wealth of information derived from researches on this topic, whilst the bibliography constitutes a work of reference for all future investigators in this field.
Not only is the technical aspect thoroughly examined, but also some important commercial developments are included. • Using the accelerator which has undergone the greatest commercial developments--amyl . nitrate — the highest cost for doping oils to bring them up to the required cetane standard, is $.0012 per cetane number per gallon; in the case of a Californian straight-run fuel, it would cost about $.002 per gallon Ito provide an oil having a 50-cetane number.
In view of the importance of America in the organization for the world's liquid-fuel supply, this matter needs the closest attention, both now, and in the immediate post-war years.
, The cetane number is, of course, the percentage of cetane in the blend which has the same ignition, quality as the fuel tested.