DIRT-TRACK RACING

DIRT-TRACK RACING

Sir,

The article on Dirt Track Racing in America is accurate and comprehensive, but appears to our perhaps provincial viewpoint to be written in English. The author's name and further writings Would be welcome.

It might be of interest to add that in addition to the Millers and Ford conversions, there are two successful dirt track cars built by the Ambler brothers, around war-time Hispano-Suiza airplane motor cylinder blocks, producing consequently left and right-hand motor assemblies. They have Chrysler front axles and Ford rear axles. Most of the other parts were made as needed. By way of apology—as Our racing has been exclusively on oval tracks, we did not have suitable ears for the Vanderbilt Cup Race. We hope to give you some worth-while competition next year. E. R. MORTON. New York City,

U.S.A. * * * * Sir,

I have just read in the March issue of MOTOR SPORT that I drove a Vauxhall In the J.C.C. Rally. Actually I drove my 31-litre Bentley saloon which was substituted at the last moment.

MOTOR SPORT is still the best monthly. I am, Yours etc.,

GORDON WOOD.

Weybridge, Surrey. *

AN " HYBRID"

Sir,

Mr. McKenzie's letter in the -March issue was kindness itself. When I saw the description of my " hybrid" in cold print I expected to see some very scathing and pungent comments about the Hillman Straight Eight, and I am delighted to find that such an acknowledged expert as Mr. McKenzie also thinks that there are some latent horses in those engines. I have been anticipating trouble with the clutch, but as the linings are good

I have not replaced them—yet. As regards the gearbox, I do not feel justified in spending any money on new gears, for a point which I did not mention in my previous letter was that the cost is being kept down as low as possible, because this car is being put together as an experimental model, in the sense that

I have ideas which are rather ambitious, and I wanted to try them out first. Actually the cost of this car will be very little in excess of ;615—but when I get as far as incorporating certain RollsRoyce units in the "Mark II" model I have in view, the cost will be very different!

As far as axle shafts are concerned, there are two types in use. One type broke easily, and luckily I have the ones that did not. They only cost 22/6 in any case, and are easily fitted.

In conclusion, may I just remark that there is a reason for your comment about my " unduly harsh " gear-change coming out of the Wiggle-Woggle at the J.C.C. Brooklands Rally. My old Frazer-Nash " Coppernob "has a G.N. driving sprocket on bottom gear, which gives me a low ratio Of 15 to 1 for trials. The change up from this gear to the 7 to 1 second just has to be harsh if you don't want to wait till the crack of doom. That is why I mentioned in my letter about the hybrid that I have always wanted a five-speed gearbox. I have a 10 to 1 bottom for ordinary road use, but I can't use them both consecutively. I am, Yours etc., ROBERT PEAT-v. Winchester,

Hants. *

SLEEVE VALVES

Sir,

I was extreniely interested to note your article in " Rumblings" headed " Sleeve Valves " in this month's MOTOR SPORT. Although to-day, as you suggest, the sleeve valve appears almost extinct in the automobile world, there seems a possibility of its use for aircraft in the near future.

It is rather interesting to note that in. his lecture (on December 7th, 1933) before the Royal Aeronautical Soeiety, Mr. A. H. R. Fedden stated the following claims for the sleeve-valve engine.

1. Greater all-round thermal efficiency over poppet valve.

2. For given cylinder capacity approximately one compression ratio higher can be used, on any given octan No. fuel.

3. Lower fuel and oil consumption.

4. Lower cost of production.

5. Lower cost of maintenance. 6. Less deleterious effects from leaded

fuels. This applies to single sleeve engines, apparently one of the greatest disadvantages was the weakness of the joint which throws the valve and this has been overcome by the Bristol Aeroplane Co.

At the time of this paper the Bristol Perseus had gone through its type test, and last year at the Paris Salon the 14cylinder Hercules made its appearance as the most powerful air-cooled engine in the show. Which goes to show that Mr. Fedden still has confidence in sleeves.

Is this not one line in which motorracing could prove its utility, i.e., by developing the sleeve. Would not the extra power and reliability make up for the possible increase in weight at first?

It might be pointed out here that the difference between aircraft and racingcar engines is so great that the above suggested advantages would not necessarily apply to the latter. However if one considers pertormance in terms of " B.H.P. per square inch of piston " and " piston speed " instead of

" R.P.M." and " " -a great similarity can be struck.

The B.M.E.P. developed in the " R " engine was 285 lb. per square inch, surely this figure must often be exceeded nowadays in racing engines and yct one never hears much about valves and seats suffering from maximum temperatures and pressures. The E.R.A. is the only example. I have heard of with metallic filled exhaust valves, which rather goes against my attempt at pointing out some similarity between the types. But although some modern aero engines exhaust upwards of 100 b.h.p. per valve, the valves. are correspondingly larger and accordingly have a bigger. volume to dissipate the heat through. I quite expect to be hauled Over the coals_ for this !

Summing up, if racing cars do suffer from the same critical valve trouble that aero-engines do (or conditions approaching to it), then this aircraft development is worthy of mention in an article deploring the lack of sleeves to-day.

Whether this letter is worthy of publication or not, I should be most sincerely interested to have your views. The reference to the 112 b.h.p. at 5,000 r.p.m. for the P.N. Shelsley I think is as stated on the power curve on the P.N. stand at the show this year. I am, Yours etc.,

R. P. G. JONES. Northfield,

Birmingham. Sir,

I have read the letter from Mr. M. McEvoy published in last month's issueof MOTOR SPORT. As Mr. McEvoy says, he and Mr. Pomeroy designed the twin overhead camshaft cylinder heads for the " R " type M.G., and As your editor's note at

the foot of Mr. McEvoy's letter states, the first of these heads was fitted to its block in our racing shops ; the actual position was that when the scheme of producing these twin-cam heads was first suggested and Messrs. McEvoy and POtheroy got to work on the design, we lent them a complete R-type M.G. to provide the necessary data and when the first head was completed it was brought to our workshops where all the preliminary trials and tests were carried out on our test bench under the supervision of Messrs. McEvoy, Pomeroy and W. E. Wilkinson. I am, Yours etc., KINNETTI D. EVANS. Bellevue Garage,

.

THE "OLD U NS "

Sir,

As -0, regular reader of your excellent paper, and one who is especially interested in the historical aspect of motoring, I read with considerable interest Mr. Boddy's article in your March number. I think, however, that he is wrong in saying that the sports-car, as something quite separate from the touring car, is a post-war development.

Before the War, such vehicles were not generally called " sports-cars "—" sporting " or "fast touring " car was the usual expression. The fitting of o.h. valves to the Vauxhalls (not only the 30/98) of 1923 did not change their character or purpose ; but it did more or less coincide with the change or expression. I have before me as I write an advertisement in The Motor" of 1911. for Hispano-Suizas. Five chassis were made, all of 80 mm. bore ; two had strokes of 110 and 130 mm. respectively, and were

alleged to do 42 and 48 in with four passengers. The 180 mm. stroke cars had three lengths of wheelbase ; the " extra long " did 62 m.p.h., the " long " 66, and the short 72 m.p.h. with two passengers. If this last was not what we should now call a " sports-car " then words mean nothing. One other point—are we expected to believe everything we read on the Fiat "

500's" speedometer ? Anyway, please put a stop-watch onto the V8 Jensen, and anything else you test. I remain, Yours etc.,

B. M. R. SAmurasoN. Mr. Boddy tells us that he is perfectly willing to concede that in terms of maximum speed the 1911 Hispano-Suizas, and many more of the " old 'tins," were something of a match for many sports-cars of the post-war era. But, whereas after the War the term " sports-car " came into being and was intended to suggest speed, acceleration, and braking all of a higher order than in a utility car, before the War these rapid touring, " sporting " or "fast touring" cars excelled solely in respect of speed capabilities, no notice being generally taken of quick pick-up in those times, while we believe we are correct in suggesting that brakes remained just as on the slower stuff and that cording of the springs, with, perhaps, the addition of weird snubber, was the soles

attempt made to improve the roadclinging qualities.

So far as the Fiat 500 is concerned, we did. not put this through a full road-test, otherwise it would have been taken to Brooklands and timed against the watch. But we are assured by Mr. lason-Cibson, who loaned the car, that it does do a genuine 60 m.p.h. under fa vt ,Orable conditions, and that he is prepared to substantiate this claim. We had no opportunity to obtain performance figures and merely gave impressions of the Fiat as we found it during a day's road motoring. In future full r, tad -tests, all performance fignres will be checked against the watch, which is normal MoTOR SPORT practice -incidentally, we cannot resist pointing out that the II ispano's 72 m.p.h. has not been confirmed by Mr. Samuelson's stop-watch.—Ed.

SPRINT EVENTS AND SAFETY

Sir, We have just read an article signed W. B. on page 137 of the March issue of MOTOR SPORT' in which you say that :—

" Yet Shelsley has a good record, and the Alta accident this year occurred beyond the finish, due, we believe, to a stuck throttle."

We are very surprised and not a little annoyed that you should say this in view of the fact that there is not an atom of truth in it and it may put people off who were going to buy an Alta, on the grounds of bad workmanship.

Actually we have a letter written by Mrs. 24illhigtoxt to the writer in Much she says her shoe came off and jammed the throttle, and she forgot to switch off or anything.

As a precaution the writer made a consulting engineer examine the car after the accident, and also drove the car down the hill himself after the accident. I am, Yours etc., G. TNYLOR. Alta Car & Engineering Co., Ltd., Fuller's Way, Kingston By-Pass,

Surbiton. We are sorry that the statement in the article in cpiestion has caused annoyance to Mr. Taylor, and we are very glad to have the opportunity of giving publicity

to the true state of affairs. Actually, although we understood the cause of the smash to have been a stuck throttle, we never connected this with bad workmanship—indeed, we imagined the throttle to be jambed by something amiss in the cockpit, and regret that we did not emphasise this point. Incidentally, this should be a lesson to racing drivers to secure their wearing apparel properly before driving—and for racing managers to see that this matter is not overlooked in the excitement of the moments that precede the fall of the flag.—Ed. We welcome letters for publication in these columns. Letters intended for publication must be written on one side of the paper only and they may be signed with a nom-de-plume, but the name and address of the writer

must be enclosed.

THE TYPHOON SUPERCHARGER

Sir,

I wish to express my whole-hearted appreciation to you for forwarding the communications from readers regarding the " Typhoon supercharger." I am simply inundated with enqiiiries for catalogues etc.

. Unfortunately I have run out of literature so am forwarding all names and addresses of those whom I am unable at present to supply to the Co.'s factory in U.S.A., who will forward them all the necessary data in due course. I wish to thank all the readers in Liverpool, Newcastle, Sheffield, Belfast,

Bristol, Birmingham, Winchester, London, the Ford Club in Sheffield, readers in B111111(-y and Cardiff, numerous others in Wales, fetters have just poured in. I am, Yours etc.,

W. F. HALLINVELI. Wothorpe, Stamford,

Lincolnshire. Sir,

With reference to your very interesting article in last month's issue Of MoToR SPoRT—" On achieving High Performance." We hasten to correct a misunderstanding which has apparently arisen in connection with the new JenSen 34-litre car.

On page 132, we notice that our name is coupled with that of The Railton, Bro ugh-Superior and Lammas-Graham, which names are mentioned as being naturalised Americans.

We would point out that although the Jensen chassis is fitted with the main parts of a Ford V8 engine, none of the parts used. in the engine are of American manufacture, the whole being made and assembled in this country. In view of this error, we shall be pleased if you will publish a paragraph fully explaining the above, I am, Yours etc., Jensen Motors Ltd., R. JT.:.NsEx, Director. West Bromwich,

England. We gladly publish this letter from Messrs. Jensen Motors Ltd., as they are naturally anxious to emphasise that the Jensen car is of British manufacture throughout. But, as they point out, certain Ford VS engine parts are incorporated and, although these are, of course, British made, Mr. Boddy, committer of the error in question, is one of those queer mortals who see a certain group of automobiles as " American," regardless of whether they originate there or in Canada

or in this country. And America certainly deserves sonic credit for having evolved the Ford V8 which, as Mr. Daddy emphasised, is a very remarkable car. But Jensen Motors Ltd. equally deserve credit for offering us an all British production possessing the merits of the Ford V8 and some others all its own, SO we gladly publish their letter and add our apology.—Ed.