HIGHER EFFICIENCY

Ellesmere Guardian, Volume XLVI, Issue 3231, 26 June 1928, Page 2

HIGHER EFFICIENCY

INCREASING COMPRESSION

In an effort toward greater efficiency there is a tendency to increase the engine compression. The satisfactory operation of a high-compression engine is dependent upon a suitable fuel being provided. As the compression in the automobile engine is increased good results are secured up to a certain point. If the compression is too high the engine will knock and the service the motorist gets will be unsatisfactory. However, engines which have high compression will give acceptable performance if an anti-knock fuel is used. The higher the compression the more important it is that the cylinders be kept free of carbon. In an engine of medium compression an ordinary gasoline may be used, until a deposit of carbon in the cylinders causes the engine to knock. When this knocking j becomes evident the operator may resort to antiknock fuels and get re- | suits similar to those obtained from a | high-compression engine. The cause of detonation of the fuel I under high compression is a problem for the engineers. The important con- | sideration for the purchaser and oper-, ator of the car lies in the fact that high compression engines produce more power and more work per gallon of fuel consumed. Special fuels have been created which will work suitably in such engines,~and both the improved engines and the improved fuels are now generally available. Increasingly the standard makes are powered with high-compression motors. 'Eventually this will probably be the general practice. The principle involved in the engine design is not eom- ; plicated. The compression ratio of the j average automobile, that is, the ratio |of the volume of the cylinder on the intake stroke with the piston down to | its volume at maximum compression, with the piston at the top of its travel, has generally been about 4i to 1. Using regular petrol an engine of this type will ordinarily give the owner little trouble from knocking. If the compression rate of the engine is increased above 4.S its power output when the throttle is open and ordinary gasoline is used will be somewhat reduced, because the tendency to knock will become increased. If the throttle is partly open such an engine will show a saving on gasoline compared to the lower-compression engine. With a perfectly planned fuel the compression can be raised to as high a figure as 7 to 1 with even greater economies in fuel and a greater amount of power. In 1927 some of the automobiles manufactured in the United States had a compression ration of 5 to 1, and some of the 1928 stock models are said to have as high a ratio as 6 to 1. These cars, if satisfactory anti-knock gasoline is used, can be expected to get more miles per gallon and more actual power output.

If one will compare the day after

day performance of a 5 to 1 ratio engine using an ordinary gasoline with the operation of the same engine using a first-class anti-knock gasoline obc can reasonably expect to find a net increase of about 20 per cent, in the number of miles per gallon. One can also expect to find' greater power in climbing hills or in accelerating quickly. The same engine with a compression ration of 6 to 1, using the best anti- ' knock fuel, will show savings up to 40 per cent, as measured in miles per gal- , lon when compared with an engine possessing a compression ratio of 4§ to 1. This revision in engine design can be accomplished by lengthening the co* ; necting rod or lowering the cylinder head, making possible either smaller, lighter engines or higher power output from existing sizes and weights. When this fine adjustment between the compression of the engine and the quality of fuel is finally accomplished there will be a maximum of power with a minimum of fuel used. There is some experimenting going on to perfect an automobile engine which will function efficiently with gasoline containing a higher sulphur content than at present, which is about 0.1 per cent. Success in this direction would effect large economies in the refining operation of gasoline. Other efforts being made to improve the automobile engine design and fabrication include the general use of the light metal pistons; also to a certain «extent chronium-plated bearings, botb of which, it is expected, will yield real savings in fuel.