RUMBLINGS, January 1939

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36

This Supercharging SUPERC.HAR( ; I NG of ordinary road-cars is ever a fascinating topic, for all save the very fortunate can do with more urge beneath the throttle foot, and yet not so many wish to go to the trouble of super-tuning or hotting up and the more frequent attention that this entails. Unfortunately, you cannot buy a blower in a big cardboard box, tack it onto your engine, and sail past Mr. Smith and Mr. Brown in their identical (but unblovvn) motors, and still sleep soundly at nights. In the first place, a supercharger must be correctly applied, and not so many engineers have the knowledge or have had sufficient experi ence to do the thing correctly. Then, not every little power-unit likes being forcibly-fed. And, even correctly fitted and applied, to a sound engine, blowing almost always means much heavier fuel consumption, because in this planet you never get something for nothing. You have to rotate your blower or compressor and you enjoy using the urge it gives, and in consequence you burn more fuel—usually lots more

fuel. Nevertheless, the addition of a supercharger gives advantages that cannot well be attained in any other way. Let us have a look at supercharger application in general.

About the first that the ordinary everyday motorist heard about supercharging was that Mercedes were applying it to certain of their production models— incidentally, before they and, later, Fiat, Delage, Alfa-Romeo and Sunbeam, etc., used it for racing. In 1925 MOTOR SPORT road-tested the 12/40 h.p. Mercedes but, even then, supercharging figured only on the more expensive cars and was regarded by Mr. Everyman as he to-day thinks of rotary valves and direct fuel injection. Mercedes, of course, sucked from the carburetter and continue to do so to this day, save on the more recent of their G.P. cars. Some years ago the writer had a very instructive correspondence with the leading supercharging authorities on this question of whether it is better to blow or to suck. Mere. had the throttleactuated clutch control, which some engineers believe

to be the most sane application of forced induction yet applied to ordinary mortals’ cars. Stutz also used a clutch control on the few blown jobs they made, also sucking from the gas-works, and last year Atalanta tried clutch control with normal positioning of the supercharger—but in both instances a hand-lever operated the clutch.

Actually, before Mercedes became sufficiently satisfied with supercharging to serve it up to their clients, the Sizaire brothers, and Marc Birkigt of HispanoSuiza, had applied centrifugal blowers to four cylinder engines, as early as 1911.

By 1923-4, apart from G.P. cars, supercharging was becoming quite an opeh book to racing folk. Austin used it for record work, H. Hagens, of British Anzani, applied it to Horstmann racing-cars, and single and twin-cylinder motor-bicycles appeared with boosters. Capt. G. E. T. Evston had been producing the Powerplus compressor for use in other fields and developed it for automobile work and a few sports-cars had this proprietary blower fitted, while French sports-cars had the Cozette compressor inflicted on them, Austin and Lea-Francis, in this country, making use of this supercharger. So supercharging became more generally understood and attempts were launched to popularise proprietary blowers. The Galley Radiator people took up the Cozette and J. A. McF,voy sponsored the German Zoller vane compressor. Laurence Pomeroy, Junr., who now does so much to enliven one’s weekly dose of ” The Motor,” first displayed his literary genius in writing up the Zoller compressor, with which he was associated in company with McEvoy. Very soon, tacking on a blower became the accepted thing to do when you craved non-standard performance. The Centric vane-compressor and the Marshall Rootsblower came along and simple fittings and belt-drive enabled installations to be rigged up on Morris Eight, Ford Bight, M.G. and even Jowett engines, not too expensively. Granville Grenfell built himself a shed on Brooklands Aerodrome and more or less specialised in such installations, even to putting a blower beneath the floor boards of an aged Armstrong-Siddeley and driving it by belt from the carden-shaft. Incidentally, he taught L. M. Ballamy all he knows of this new cult of tacking on forced-induction. Francis Grenfell used to prowl round talking high technicalities—his favourite subject was the speed at which different makes of vane-compressors developed maximum

‘efficiency. Few argued with him . . .

Hereabouts Amherst Villiers got very cross because :a motor-writer unwisely laughed at his experiment of supercharging a 40/50 Rolls-Royce with a blower -driven by a separate Austin Seven engine. The fun now began in earnest. Those whose fortunes were bound up in vane-type compressors preached far and wide that the Roots-blower had to be made very carefully to maintain accurate clearances, that it lost efficiency with wear, and that it had to function very fast to be of value. On the other hand, those who had their shirts staked on the Roots-type supercharger told of the complication of a vane-compressor, of difficulties of lubricating it and of oil used in so doing going into the engine. Actually, supercharging had made commendable headway and early shortcomings, such as bad running and starting on account of fuel deposition, noise, and the need to add oil to the fuel (the first blown M.G. asked for over a quart of oil per tankful of fuel), had mostly been banished. The primary worry now was that production engines, particularly those of utility type, disliked more than about 5 lb. blow, and if a blower or compressor was made to do useful work low down the speed range it became too much of a good thing at cruising and above-cruising .speeds. On the other hand, if arranged to humour the -engine at high knots, unblown motors were on an ‘equality with the blown jobs. However, there was no shortage of proprietary superchargers. We have been introduced to the Shorrok-Haydock axial vane-compressor, the Centric, Zoller, Gillett, Cozette, Powerplus, Velox and Foxwell vane superchargers, the Berk, Marshall, David Brown and Jamieson Roots blowers and the Zeus, which cheerfully contrived to be both a Roots and a vane-instrument. More recently, Arnott has made the Amott compressor, rather like .a Centric, and mated it up to his excellent carburetter, which can be used as a vertical, horizontal or downdraught gas-producer, at will. Personally, we experienced some quite un-catalogue happenings with proprietary-blown motors. Heavy fuel consumption was universal, run big-ends not uncommon, one early blown M.G. blew out the complete insides of its sparking plugs, and a Ford lost its complete installation at the bottom of a long hill. The only car which gave great urge and a reasonable fuel consumption ran splendidly for two years and then ate its compressor vanes, to the detriment of its bearings. Perhaps the early nineteen-thirties must be regarded as the pioneer years of tacked-on forcedinduction. Meanwhile, Pomeroy and McEvoy made a bold bid to overcome the urge-at-low-revs./burst-athigh-revs. problem. First, they introduced the external

piston-action pressure control. Later they seemed less inclined to use this component, but in 1936 introduced the ” Velox ” variable delivery compressor, in which movement of the vanes controls the output.

They had previously learnt how to use Clayton-Still delivery piping to ensure simple inter-cooling, thus pioneering in another sphere of supercharge application. Just as the ” Velox ” was being launched, Pomeroy threw down the spanner and took up the pen, but this unique supercharger is believed to have valuable application in the aero-engine field. And now we are up to date.

Usually these paragraphs point some sort of a moral, or attempt to do so. But having got this considerable bit of supercharger history off our chests, we will leave it to you, dear reader, to draw what conclusions you can as to the future of supercharging. Possibly this is a matter which is largely in your own hands.

The Next Formula

Considerable attention having been given of late, in print and spoken word, to the desirability of producing a team of British Grand Prix Formula cars, naturally people have turned to discussing the next G.P. Formula, for, should the miracle happen, our team could not hope to be effective under the existing ruling, which will hold good until 1941. In the first place, we can hardly agitate for a change before then, because Germany has spent good money on the production of all-conquering 3-litre cars to Formula requirements and cannot be expected to scrap them just because other nations have found the ruling unpalatable. But certainly we may consider what the 1941 Formula should be. It is not often that our two leading motoring weeklies disagree completely, but, on this subject, while the sports editor of one of them advocates a plain I flitre Formula, the technical editor of the other feels that, whatever happens, the 1i-litre class should continue to exist as a separate entity. The latter not only argues that ii-litre cars would cost more than present Formula bolides, but that, outstanding as this country is in this class at present, it might not continue so if subsidised nations turned their whole attention to 11-litres. Those in favour of a 11–litre Formula point to the rosy possibilities of bigger entry lists and the greater chance this country would probably have of success. As we see it, it might have been a good policy to plead for the 1 flitre Formula when our E.R.A. team was at full strength. Unfortunately, Humphrey Cook has announced that he can no longer maintain it and that it must lapse unless f,5,000 can be raised annually by public subscription to support it. We would like to feel that this sum will be raised and that the team will carry on, but it is over twenty times the amount so far raised annually by the E. R.A. Club—and Sam Green has not been backward over publicity. If the official E.R.A. team, like the Sunbeam and Bentley teams of yore, fades, doubtless independent drivers of E.R.A.s will still effectively meet Continental opposition in the 1k-litre class, even in three years’

time. But they could hardly represent us in full Formula racing and a 1-i-litre Formula would spell lost prestige in both categories (G.P. and class racing) unless our £250,000 dream-team happily materialises. Furthermore, we cannot see that high-revving highly-boosted 1+-litres will do any more to hand on lessons of value to the touring-car designer than the present 3-litre cars. Even if our team is shaping, it might be unwise to shout too loudly for the 1+-litre Formula. We must remember that up to now the International Formula has not unduly favoured any particular nation at its introduction. The first ruling sought to reduce the speed of road-racing cars ; the existing Formula to equalise the chances of various

sized cars. At first, Italy, then Germany, became masters of the situation by building the most suitable cars. So, if we shout for a 1+-litre Formula in 1941, Germany will be justified in shouting equally loudly for continuation of the existing ruling, or, perhaps reversion to the old Formula, France in demanding an unblown 4+-litre Formula and America probably for an unblown ruling. Italy might, or might not, join us in wanting a 1+-litre limit. We do not profess to know how seriously the representatives of the various nations take the A.I.A.C.R. meeting at which the terms of the new Formula are decided, but certainly we can foresee trouble if a ruling is discussed which expressly favours one country more than another. G.P. racing is at present not at a very high ebb and any strong feeling at this important gathering might well kill essential subsidy which alone makes G.P.

racing possible. So, granting that a 1+-litre ruling would allow more independents to compete, which would be a good thing, and that this country is a nation of small car users, we still do not wish for an International 1+-litre Formula.

The E.R.A. Club, in the December issue of “Hearsay,” also votes against a 1+-litre Formula, preferring one of 3-litres with no weight restrictions of any kind. To suggest a useful new Formula is not easy. Banning all forms of special fuel might assist towards making to-day’s racing-car once again to-morrow’s touring car. Michael McEvoy wants an oil-engine Formula—which has points in its favour but is a thing one can never see really coming about—we haven’t yet got Diesel classes, based on capacity, in the record field, in spite of this paper’s emphasis on the need to develop oil-engines of all sizes, particularly those suited to private cars and light commercial vehicles, like the specially hotted Perkins unit used by Munday

in the Thomas-Special. Maximum weight rulings play into the hands of those who are substantially subsidised and can experiment extensively with light alloys. Why not a slight modification of the existing Formula, to give the unblown cars and 1+-litre cars a fairer chance in relation to the bigger blown machines ? Such a change need not wait until 1941, because the Germans would welcome keener competition for their existing 3-litre cars. If we cannot suggest a really good new Formula, at all events we arc going to repeat a suggestion which MOTOR SPORT made last October. It is that we should have, right away, a classic 1+-litre scratch contest. Will it be Mr. Craner, Mr. Bradley, Mr. Edwards, Mr. Morgan or Mr. Scannell who will get the credit for organising such a race ? We would like to see it held at Donington on the Saturday preceding the

next British Grand Prix, which we hope Mr. Craner will run on a Sunday this year. At least Mr. Craner is sympathetic towards 1+-litre cars. If he does not give us this race, Brooklands should give Londoners. an opportunity to see it. The ” 200 ” used to be the 1+-litre classic and might well revert to its old form, over the Campbell circuit. The Palace circuit is hardly suited to a long-distance race but Mr. Edwards might get those Alfa and Maserati drivers who would come over for this race to a curtain-raiser at the London track on the Saturday before the big contest. On the other hand, so many B.R.D.C. drivers handle 1+-litre cars that surely Mr. Scannell is interested ? Anyway,* let us have a 1+-litre G.P. One of the most impressive things about the last Donington G.P. was the fine showing of the E.R.A.s. Let us further emphasise our 1+-litre leadership. We might make the race one of 400 miles, the better to test reliability and pit work. And we should hold it now, while the existing Formula classes the 1+-litre cars as a separate entity.

Odd Spots

J. K. Mason writes that his Brescia Bugatti has done 3,000 miles without trouble and runs up to 5,200 r.p.m. He uses Champion R1 plugs and has no oilingup bothers.

S. H. Allard, one of our foremost trials drivers, is Director of Adlards Motors Ltd., who handle Ford. passenger-car and commercial sales and service from depots at Putney, Streatham and Brixton. As a hobby he builds and drives Allard-Specials.

M. S. Soames has built himself a very special Morgan three-wheeler.

Humphrey Symons is attempting to drive from London to Cape Town in seventeen days with a specially-equipped 18/85 Wolseley saloon.

H.R.G. have introduced a 9 h.p. Singer Bantamengined model, priced at £280. It has the same chassis features as the 85 m.p.h. 1+-litre car, which now has a three-bearing 1+-litre o.h.c. Singer engine in place of the former push-rod Meadows unit. The new car weighs 13i cwt. and is said to do 75 to 80 m.p.h. and 35 m.p.g. A 9 h.p. model has been supplied to a well known trials man.

The first big British race of 1939 is the B.R.D.C. Empire Trophy, on April 1st.

The J.C.C. may change its title to ” British Motor Club.”

Major Gardner hopes to reach about 210 m.p.h. with his M.G. when he takes it to Germany again in April.

The ” Jabberwock ” Ford V8 team seems likely to be disbanded. The cars are up for sale.

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