Oil Engines and
Page 43
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their Fuel
TWO recent memoranda dealing with fuel for compression-ignition engines, issued by the Society of Motor IsIanufacturers and Traders, are of marked interest to our readers.
It is pointed out that the use, by misinformed persons, of the term
,.crude oil" has led to much confusion. Crude oil is a virgin oil, straight from the wall, which has not been subjected to any refining process. This, of course, makes it cheap compared with refined products ; high-speed compression-ignition engines will not run on this liquid, with the exception of one brand. Crude is used as a aubstitate for coal in furnaces, etc.
Fuel for existing types of compression-ignition engine, as used in road Vehicles, must be of a refined type, closely related to gas oil, which is distilled from the crude just after kerosene has been taken off. The processes and plant required for its production are just as costly as those involved in producing other petroleum derivatives.
The memoranda clearly point out the .position with regard to fuel cost. From a given quantity of crude a certain cash return must be obtained, no matter what form its derivatives may take. If the percentage of gas oil be increased the percentage of other materials must decrease, therefore the price must be
adjiisted to compensate; it .follow that fuel for compression-ignition engines will Cost more as the -demand increases.
At the present time petrol prices inchide a tax of 64. per gallon ; It seeing likely to suppose that, in the event of an increasing demand, any substitute derived from the same source would be taxed similarly. One of the major items in assessing the cost of petrol is the distributing charge: When the method of delivery by barrel, obtaining at present, gives way to more convenient systems the price will rise.
It is pointed out that improvements in engine design will tend towards the possibility of using heavier fuels; viscosity alone cannot be taken as a guide to suitability of a fuel, as tar oils, although of low viscosity, are not generally adapted for this work.
The memoranda deal with the higher initial cost of the oil engine, its maintenance charges----which are somewhat uncertain at present—but do not adequately stress the advantages of its higher. thermal effiCiency.