ALCOHOL AS A PRACTICAL FUEL.
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The Elimination of Pinking and the Attainment of Lower Fuel Costs are Among Important Advantages Obtainable.
KOHOL FUEL can now be obtained in London, Liverpool, and Glasgow for 1s. 9d. per gallon in bulk or in barrels. The usual trade prices arequoted at a figure below this retail price. Thus, it is commercially possible to obtain a British home-produced fuel at a price lower than that of petrol, and this may have far-reaching results. During the past year -several important concerns have been experimenting largely with alcohol as a fuel for internal-combustion engines of the commercial vehicle type, and, and by giving a résumé of the
results attained and the knowledge gained, we shall be able to provide some indication of the proper way in which alcohol can `be employed to advantage.
Although Commercial Discol, as the fuel which is sold by the Distillers Co., Ltd., is known, costs only is. 9d. per gallon, it would not be commercially advantageous to run a vehicle on this fuel alone, for it gives a very much poorer fuel consumption than that which is obtained on petrol, so that the actual cost per fuel-mile would be higher. Its chief attraction lies in the 'fact tlidt, by its use, the undesirable pinking which is prevalent in some commercial vehicle, engines can be absolutely eliminated. This means that a much higher compreision ratio can be used, with the result that.the mileage per gallon is very considerably increased, more power is produced, and a big reduction in costs is thus obtained.
• There are two methods of introducing Discol into the fuel system of an engine. One is to raise the compression until a ratio of about 5 to 1 is reached, when Discol can be used advantageously in the ordinary way. It' may here be mentioned that we have personally proved that it does not make starting any more difficult, and does not appear to have any illeffects on the ordinary fuel tanks. There is no objectionable smell ; in fact, there is less odour noticeable than when benzole is utilized.
The other method is to run .petrol and alcohol together, feeding them to fheengine through separate carburetting systems.
Tills method is now considered to be the most convenient. It also demands a higher Compression ratio, however, unless the alcohol is only to be used as a "dope."
$14 Another of the advantages of alcohol is that an increase in power is obtained. This is by reason of the fact that alcohol has a very high latent heat of vaporization (nearly four times that of petrol), and on the induction stroke it coals the charge and thus increases its density, which conseqiie,ntly enables the engine to inspire a greater quantity of mixture. Bench tests have shown that the exhaust valves of an engine were much cooler when running on alcohol with a high compression ratio than was the case when the compression was lowered and petrol alone was used.
We illustrate on these pages some of the devices that have been produced to enable two fuels to be used. The Billie' carburetter, made by Bifuel, Ltd., which concern controls the Ricardo and Dodson patented system, consists of two carburetters feeding a common induction pipe, the larger float chamber containing petrol, whilst the other is coupled to the aleohol. fuel supply. When the accelerator pedal of an engine equipped with this Bifuel system is only depressed a little, the throttle of the petrol carburetter alone is opened ; but, as more power is required and the accelerator is further depressed, the throttle barrel of the alcohol carburetter is opened, the comparative degree of opening obtained on both carburetters being governed by differentiating devices that permit them both to be fully open at once, but .causes the alcohol carburetter to close earlier than does the instrument which is dealing with petrol.
Let us suppose that this carburetting system is fitted to a.high-compression engine that would pink badly., if it were given anything like full throttle on petrol. At small throttle openings the cylinders draw their supply from the petrol carburetter, but, by reason of the fact that they are not filled with mixture, the actual compression pressure inside the heads is not sufficiently high to cause pinking, and
it is only when sufficient mixture is being drawn into the cylinders to give an actual compression pressure high enough to induce detonation that the alcohol fuel, acting as a dope or anti-detonant, is introduced and comes into play. Thus, one obtains the advantages of a high-speed high-compression engine with out losing any of
.5calion Pipe polo Adj—W13 Sues the docility at low Addax!, Jyslan-+ speeds. Te st s extraordinary consumption figures can be obtained on actual road tests, whilst, on the bench, the consumption per brake h.p.-hour is very remarkable. Another system Oat allows alcohol to be used as an anti-detonant is known as the Hobson NonPinker. This is simply fitted to the induction pipe and coupled direct to the alcohol fuel supply. In its construction a small needle valve controlled by a diaphragm is employed, the valve being shut when the depression in the induction pipe is big (a state of affairs that is experienced on small throttle openings), but the needle lifts of its seat as the dePression decreases with the increase of throttle opening, and thus, again, we have alcohol being introduced into the mixture when the cylinders are being filled and when a high-compression pressure is being obtained. The Zenith Carburetter Co., Ltd., have taken out a patent fara system that couples the compensator and pilot jets of their carburetters with a float chamber containing petrol, whilst the main jet is coupled up to a separate float chamber to which alcohol is fed, the normal passage from the petrol float chamber to the main jet being blocke&by some suitable method. This appears to be a very neat way of obtaining the desired end. Thus, it will be seen that all the spadework has twen done to enable home-produced alcohol to be used to decrease running costs. In the near future we hope to be in a position to publish actual test figures which will give clear indication of the economies that can be effected by the utilization of the methods described above, and which show in plain figures what may be expected.