THE CASE FOR THE LOW-SPEED RACNG ENGINE
Lost month the possibility of bigger-engined Brooklands cars was touched upon in Rumblings. In this article a contributor enlarges on the subject. —Ed. Before I detail what I feel to be a perfectly reasonable case for the further development of the large low-speed type of engine for racing I must make it quite clear that I am not attacking the very remarkable modern small cars. In this article I wish to discuss outer-circuit ” lappery ” of Brooklands Track at speeds upwards of 100 m.p.h., for which purpose, as I shall endeavour to show, I consider that the large slow-revving engine has
certain very distinct advantages. For every other phase of normal highspeed work one would naturally advocate the modern small engine, which as a result of intensive past development and research, is deservedly popular, and obviously most suited to road racing, sprint work, trials conditions, and rapid motoring on the road, the last-named either apart from, or allied to, coinpetition driving. It is for high-speed track racing that I consider that the large capacity power unit justiffes further development, this class of racin engine having recei zed very little attention, at any rate of recent years. Looking at the matter from the viewpoint of a person about to embark on a season’s racing at Brooklands, and who intends to compete exclusively in B.A.R.C. Outer-Circuit Handicaps and, perhaps, in the annual 500-Mile Race, it would seem that a car with an engine capable of pulling a very high gearratio is far more worthy of consideration than may be apparent at first sight. Likewise, this class of racing-car should interest prospective attackers of longdistance class records, and those whose
work entails lengthy spells of high-speed running. The cost of racing can be considered under two headings fixed costs, and (b) variable costs. Fixed costs
embrace first cOst of car, entry fees, stabling charges, insurance, etc. Variable costs, in so far as different types of cars are concerned, are represented by fuel, oil, tyres, replacement of worn accessories, repairs and experiments necessary for progressive speed increase.
I would ask you to consider the probable cost of a season’s racing at Brooklands, with a small and a large-engined racingcar, respectively. The small car can be any modern racing-job capable of a lap speed of at least 90 m.p.h. As to the large-engined racing-car, we will first consider a sports chassis, or one of the older racing-cars, developed to achieve a speed equal to that Of the _small car, but at a much lower engine speed, on account of a top-gear ratio in the neighbourhood of 3 to 1. The first cost of these respective types is difficult to determine, but if we assume that the price of a small car capable of a lap speed of at least 100 m.p.h. will be roughly equal to that of the combined purchase price and cost of development of an older large car of equivalent speed, there will be no cause for argument. Entry fees, stabling and insurance are not affected by the type of car. Coming to variable costs, fast small racing-cars are notoriously heavy on fuel, and although in theory a given quantity of fuel must be burned to perform a given job of work, irrespective of crankshaft Speeds, I suggest that at the end of the season’s racing there will be very little to choose between the comparative fuel bills. Much the same applies, in my opinion, to the oil consumption, spread over a season’s racing. The small car will probably be considerably easier New
on tyres, although if we assume that racing activities are confined to one long and one short handicap at each B:A.R.C. meeting, a set of tyres will only be called upon to run about sixty-two miles in a season. Add thirty practice laps before each meeting, also a figure for miscellaneous mileage, and even then it wil.1 beevident that in both cases the question of tyre wear in the first season hardly arises. So far, the expenses bill for the rival types remains fairly level, but we now have to consider replacement of worn accessories, repairs, and the cost of any modifications deemed advisable during a season’s racing. It is under these threeheadings that I should expect the large
engined car to score. Again, I must emphasise that I am casting no reflection.
on the modern small racing-ears. But it is only natural to expect more attention. to be necessary in the case of a tiny unit running at anything from 5,000-6,000 r.p.m. at maximum speed, than is likely to be the ease with an engine having a capacity exceeding 3-litres, and a maximum crankshaft speed certainly not exceeding 4,000 r.p.m. at 100 m.p.h. In the same way, the chance of an expensive” blow-up” must, I suggest, be greater in the case of the fast-revving unit, speaking generally, although I concede that suitability of the individual design to Withstand varying stresses largely enters. into the matter. The question of sub-. sequent experimental modifications made in search of increased speed is, again, largely an individual matter, albeit I feel that there are more standard chassis. of over 3-litres that could be tuned to. achieve 100 m.p.h. fairly easily than is. the case with standard cars in the lightcar classes, in running over these .costs I have so. far purposely considered a lap speed of about 100 m.p.h. but if this figure is
raised to 120 m.p.h. or over, the case for the really big low-speed engine is very considerably strengthened. To attain such a speed from a car of under 1 .-litres engine speeds of upwards of 6,000 r.p.m. are involved, and the first cost of such a car will run into a four-figure sum. In Spite of remarkable progress in engine design, reliability will hardly be assured at such high rates of revolution, while at full throttle the fuel consumption of these small high-efficiency units will be in the neighbourhood of (5 m.p.g. Moreover, remember that the number of existing 120 m.p.h. light cars is not large, and that to develop the remaining types to attain this speed would need a high technique and absorb much money. Now let me unfold my plans for a cheap reliable 120-1:10 m.p.h. racing-car. Ex pressed briefly, the idea is that. of instalEng a second-hand aero-motor in a suitably modified modern chassis. There is no question but that aeroplane engines produce speed in plenty. In the old days, when there was a vogue for such power-units at Brooklands, the chassis in which they were installed were in nearly every case under-geared, and bodywork of crude streamline form was general. Nevertheless, the InghamSpecial, with a twelve-cylinder Liberty motor of 26,907 c.c.. had a lap speed of 125.77 m.p.h., 1ldridge’s Fiat with 20.981 c.c. aviation-motor was not much slower, and the famous Y-12 cylinder Sunbeam’s best race-lap was at 122.67 m.p.h. The four-seater Benz, with 21 four
cylinder engine has recorded 115.’, m.p.h., and Wares old 10-litre Fiat and the immortal 2:3-litre Maybath-engined “Chitty” both -went round at 113.45 m.p.h.
Now these old motors were never particularly safe, and obviously they would not pass the present scrutineers.
However, believe that if such engines were installed in properly-modified modern chassis a most .satisfactory super-fast type of car would result. With a maximum engine speed not exceeding about 2,000 r.p.m. expensive ” blow-ups ” would be most unlikely, and the fuel. Consumption should be better than that of supercharged super-fast baby-engines, while these big motors should hold their tune for very lengthy periods. And they would probably be quite economical on plugs.