The Supercharged Racing Car [Major Segrave sent us this article
just before leaving England for Daytona Beach.—Ed. SPECTATOR.] OFlate years there has been no more remarkable develop ment in connexion with motor-car racing than the intro- duction of the supercharger principle, which is a British inven- tion. By its aid special racing engines of only one and a half litres total capacity—which in a touring car would involve a rating of just under twelve horse-power—have been made to give more than 200 horse-power on the brake, and to propel the vehicle in which they are fitted at a speed of over 130 miles per hour. It is striking to reflect that an engine of this very modest size—which only a few years ago was being derided as too small for practical purposes—has now arrived at the point at which it is almost too fast for any existing track.
The supercharger was brought into use by the fact that ever since the War the organizations responsible for the control of racing in Europe have been steadily reducing the limit of permissible engine size with a view to encouraging the design of lighter and more efficient cars, and also with the object of keeping speeds down to reasonably safe figures. The former object has been achieved so conspicuously that the other has been partially defeated, for the truth is that though engine dimensions have been going down, average speeds have very distinctly been going up.
The supercharger offered itself as the means of obtaining a greater output of power from an engine of given size. This it does by forcing - into the cylinders a greater amount of gas than they would normally receive if the mixture entered at atmospheric pressure. The supercharger, or blower, as
it is sometimes called, is a very simple mechanism, driven from the crank shaft. European designers gel e ally make it revolve at engine speed, but in some American racing cars it is " geared up " and thus sometimes attains a speed of as much as 30,000 revolutions per minute. It is capable of adding as much as fifty per cent. to the power of the engine.
The fact that the supercharger is constantlyzoblowing mixture into the motor means that a good deal of fuel is unavoidably wasted, and hence the mileage per gallon of a 1,500 c.c. racing car is not the sort of figure which would satisfy the ordinary touring motorist, being in the neighbour_ hood of eight m.p.g. !
Recognizing this as an undesirable tendency the Auto- mobile Club de France has drawn up -special regulations for the big events, such as the Grand Prix. Under these each car will be allowed a definite quantity of fuel on which to complete the course, and if it runs dry before the full distance, it will be disqualified. This regulation is not necessarily aimed against the supercharger, but it is expected to encourage the elimination, or at least mitigation, of one of the supercharger's principal shortcomings. What the upshot will be no one can say, but it certainly will not be the extermination of the supercharger, for that is already a feature of more than one standard type of touring car, and there is reason to believe that its adherents will increase considerably in number in the not distant future.
S9 far as touring cars are concerned, there are two main schools of thought with regard to the principle of forced induction. One holds that this is a good thing and that such objectionable qualities—noise, wastefulness and compli- cation, for example—as are now associated with it will duly be removed in course of time. The other equally stoutly maintains that when there is no strict limit imposed upon engine capacity the easiest and best way to get more power is simply to increase the bore and stroke.
Personally I am a convinced believer in the future of the supercharger, for the reason that it should enable both the size and weight of power plants to be reduced. Both these arc points of importance, for clearly we want, for a given wheel base, to have the maximum accommodation in our cars, and also we want to run them as cheaply as possible.
There is another thing, too, in favour of the blower. It has no parts that have to move up and down. It merely spins like a turbine and consequently tends to make a reciprocating engine approximate more closely to the ideal condition of the steam turbine and the electric motor. With a very Small supercharged engine running at a very high rate of speed the power impulses come at such minute intervals of time that almost perfectly smooth action is attained. In these circumstances it is quite probable that we shall have in the future full-sized saloon cars, capable of a smooth and quiet sixty miles an hour, driven by supercharged engines with a rating of seven h.p. or less, and weighing, complete with every detail of equipment, something under one tcn.
If and when this occurs motor racing as a direct means of benefiting the design of the ordinary touring car will have been even more • triumphantly vindicated than it is to-day, when practically every car made is fitted with the four-wheel braking that racing alone brought to practical perfection.
Apart from the supercharger it can hardly be said that latter-day racing practice has introduced many devices which are likely to be of value to the ordinary motorist, though it has certainly contributed to procuring a much greater longevity for tyres. Undoubtedly, however, there are potentialities in some of the racing " gadgets." For instance, the flexibly spoked steering wheel, used for the purpose of insulating the driver's arms from road vibration, has possi- bilities, as also has the system of using a special' radiator
et Then,m maintain s, the to IN bueeb littler cabtei gadoubt n oil l that tiamtreasonableemmechanically v , t er enh er dItviiierel operated petrol pump will in course of time oust all other schemes of fuel supply between tank and carburettor. These things, it is true, are details, but when all is said and done, the motor car is just an agglomeration or details; and each and "eireri one must be susceptible of iridividual progress if
H. 0. D. SEGR AVE.
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