MORE ABOUT CLASS I
We have seen too many doubtful projects sponsored by reputable papers, so that we have no wish to be dogmatically optimistic about Class I ” Specials.” But as the subject seems of universal interest, we see no harm in publishing these general observation3 from Joe Lowrey’s pen. We are still anxious to review possible designs. But we have no intention of giving one each month, with working drawings—this is MOTOR SPORT, not ” Amateur Mechanics.”—Ed.I IT is often said that ” great minds think alike,” and proof of this old saying can surely be found in the mariner in whieh Mr. Neve and myself, eorni>lete strangers living hundreds of miles apart, both wrotc to MoToa SPORT independently and alincist simultaneously with the suggestion that enthusiasts
should pay more at to the possibilities of 500 c.c. vehicles. In fact, this remarkable coincidence .so shook tile Editor that, in spite of his dislike of any break with motor racing tradition and his abhorrence of anything verging on the ” doodle-bug,” he has asked for more facts and opinions on the subject of Class I vehicles.
Well, as regards any ideas I may have on ” ideal ” designs for 500 c.c. ears for racing or road use, I had better say right away that I have no intention of publishing them here. However, having taken it on Myself to preach the cause of the “kiddy-car,” I hope I can say enough to awaken interest in Class I possibilities. In considering any figures I may put forward you must bear in mind that I regard most of them as capable of being considerably improved on %%int, or perhaps even without, proper works facilities. First, then, :l W’t yrd on the subject of 500 c.c. road cars, which I expect to see in production in large numbers soon a fter the end of the war. In the years following the last N ar the most successful economy car was the Austin Seven, a ‘747 c.c. sidevalve baby of light and simple construction with, in effect, accommodation for two people and some luggage ; in the course of time it grew up and became “just another small saloon,” and in 1937 its old place was filled by the Fiat ” 500,” now making use of only 570 c.c., but bearing an astonishingly close mechanical resemblance to the original Austin Seven. In the normal course of events I expect to see, about two years after peace is restored, another really popular “twopeople-and-luggage ” baby, and with Nvartime developments in engines and fuel it should do its 60 m.p.h, with a 500 c.c. engine. [The m.p.g. rather than the m.p.h, factor is likely to decide the ” 500’s ” future.—Ed.] Having made this brief attempt to appease those who insist that racing should help improve the breed (a doctrine I agree with at heart, though 1 Cc:Jr the Great British Public has not been educated to
:-Lilpre6ztic race-bred performance and stability), let Inc get down to the question of 500 C.,:. sprint ears, which most concerns readers of MOTOR SPORT. As far as I can recollect, the only car of under 500 c.c. which has recently appeared in competition motoring is a supercharged 350 c.e. (?) two-stroke produced by Jameson, but I can only recall this running in one event, in win( h it was outclassed by the twin o.h.e. Austin racers. However, in the field of recordbreaking there have been a good many ears Of 500 c.c. (and even :150 c.c.) built, smile of which have performed very well indeed. An early effort, in this direction was a Morgan three-wheeler, built for the late Erie Fernihough before he attained wide fame for his motor-cycle records ; this vehicle being described iti the August, 1926, issue of :Myron SPoivr. Although, as a flu( (-wheeler, it is rather outside the scope of this discussion. it is interesting
to recall that this 111:1C111114′, unblown 500 c.c. J.A.P. engine. of 1925 vintage, weighed 615 lb. complete and covered 5 kilometres at 73.37 m.p.h. A fourwheeler which, about ten years later, was almost 15 m.p.h. faster over the same distance was the lk County, a fourcylinder which was virtually a sealeddown version of the typical racing car of the earlier 30’s, but with unorthodox twothrow crankshaft. Then came ” Nibbio,” a light and well-streamlined car with tubular chassis and unblown two carburetter 120 V-twin Guzzi engine, said to develop about 47 b.h.p. This car took records at speeds up to 106 m.p.h. and maintained Over 100 m.p.h. for ten miles. That, then, is very ;mull Of a thumbnail sketch of the receid history of the short distance 300 c.c. re,.ords. (Me cannot help feeling that so tar nobody has taken then, its seriously as the larger class recerds. In support of this view, I have sk( t idled out a graph showing the world’s ehissrecord speeds for the standing start kilomet (the record of most interest to 110—- lio ,
. 100 * 90 B • so
7. 60 So ASO SOh ISO 000 ..100 ZOO* s000 Soot OSi
sprint exponents) plotted against engine size ; in order to obtain a straight line graph I have used log,arillunie scales, a justifiable mathematical artifice. It. needs but a single glance at the graph to show that, while the 750 c.c. class (represented by the twin o.h.e. Austin single-seater) is well above the usual standard, the 350 c,c, and 300 c.c, class records are relatively slow at present. However, to conic down to brass tacks (as the schooinlaqer said its he leapt out of his chair), the Editor has asked not so ima.11 for these general remarks on Class I machinery as for fiats and ideas . on possible future inaehines. First, then, an idea tOr those brazen individuals whose delight it is to find loopholes in the regs. : the recipe is one really hot 500 c.c. motor1,ike, trailing two rubber-tyred 3-in. Mcceano wheels on a Meceano axle at the end of a bit of wire. If this ” mechanically ‘impelled vehicle having not less than four wheels ” is not capable of winning every single class in the average minor sprint
event it is t’me I bought a nice edible hat, and the only snag is the coninion rule that a scrutineer can ban any car without giving a reason ; and I rather 111111k he would. [We might kill off such entrants, not by banning them. but hy insisting that their ” ears ” had wheel-steering !—Ed.1 Next, a rather wild idea, applicable to any size up to 2-litres and perhaps just pr„„ji„able, A good. many OVerlwmi I”‘ 250 c.e. motor-cycles weigh only 250 ll. with full touring equipment : 1*(111.0VC all the touring emlipment and cons h two such in:whines alongside at about 3-11.. 6-in. centres with cross tubes (rather like fitting a sidecar), sling a canvas seat between the rear wheels, inter-connect the controls (mostly Bowden-operated already) and steering, and I think you could get a pretty t.10()(1, power output with a dry weight of 500 lb. The handling might be awful with such a short wheelbase and laterally tlexible forks, but at least the power,:weight/eost ratio should be good. Ineniember the Adamson 1.:S% 1 car, .1.11. ? Ed. I If you want a more orthodox layout (I certainly do not blame you if you do, but look what John Bolster gets away With !), you have virtually the choice of U motor-cycle power unit or a car unit reduced in size. Of motor-cycle units, recent TI’. models are reputed to deliver nearly 5) b.h.p., unblown and using “50!ao ” pctrol-hclizol fuel, and they have to last through a long and trying race ; if they really do this they should be pretty POd on alcohol fuel, even though they cost a sizeable bag of gold. A far cheaper anit is the dirt-track J.A.P., which used to Cost 226 new, but would hardly last out anything longer than a sprint owing to sketchy cooling and lubrication. The curves of power and m.e.p. (see page 444) are drawn from figures obligingly supplied by Messrs. J. A. Prestwich, but I believe that just before the war the peak power bad risen to about 41 b.h.p. with 14 to 1 CoMpression. It is of interest to note that this engine weigha 77f lb., 91 lb. of which is accounted for by the magneto and carburetter. For comparison I have included a curve of the nee.p. of the Q-type M.G. Midget. I do not know for certain whether this engine would stand such drastic treatment as linering down from 57 mm. to 461 mm. bore, but the Power curve is drawn on the doubtful assumption that this could be done without affecting the b.m.e.p. It is apparent
that a very good power output might he expected, but it must be remembered that the Q-type M.G. is a comparatively heavy car for sprint work ; a supercharged motor-cycle-engined car might well give a better poweriweight ratio.
Here let me digress to express a general opinion on the question of single-cylinder engines. If I were in the position of having to design a 500-cc. engine from scratch, I should ignore the single but from the point Of view of the amateur tuner Who Wants cheap power and does not mind rough running it is a different matter • the modern ” square ” 500-e.e single will run up to 7,000 r.p.m. easily, and it is rather a tall order to work poppet valves much above this speed, so that unless you can use a really advanced design throughout the engine there is little objection to the single “pint pot.” I repeat, though, that this applies only to the tuning of existing engine units of popular type. Having discussed the matter of engine units at some length, on the ground that it is the engine of a Class I car which will differ most from orthodox practice, I had better say a few words on the subject of that unfortunate necessity, the chassis. Here, even more than in the power unit, there .should be vast scope for individual ingenuity. You can take as your material wood, steel or light alloy, and you can
adopt an orthodox layout or any backbone, stressed skin, or even geodetic construction that takes your fancy. And you can suspend. it on any layout of leaf springs, coil springs, torsion bars or rubber bands you please, or leave it unsprung and trust to Mr. Dunlop. [As in the Gnome cycle car.—Ed.] My personal belief is that the chassis of a bass I car, or at any rate of an unblown example, need not be very wonderful in its road clinging ; speeds will be quite moderate except on a good course, such as the Madeira Drive, Brighton, and the really important thing is to avoid loading up the tiny engine with excess weight. The complete vehicle should only weigh about 41 cwt. if well designed, so that even the weight of the driver will be important— I should hate to see all competitors the size of jockeys, but if you have a figure like Goering you had better go for something with a bit more power on tap I Seriously, though, it would be very nice to have i.f.s. and a De Dion rear axle, but the results in this case would not be worth having if they added even a pound to the weight.
There, then, are a few more ideas on the Class I question intended not as a guide to special building, but merely as something to retain your interest in the subject. What are you going to do about it ?
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