Letters from readers

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HIGH ROAD SPEEDS

Sir,

With reference to a letter in your March issue headed "High Road Speeds," I think your correspondent, Mr. Jarvis, would be interested in my experiences testing experimental and racing motorcycles on the road for Messrs. VincentH.R.D. Co. of Stevenage, with which firm I no longer have any connection.

On several stretches of the Great North Road between London and Stevenage I have motored at speeds exceeding the 100 mark, though a test run often had to be stopped on the appearance of traffic. The highest speed which I have recorded is 107 m.p.h. on the Letchworth By-Pass (just north of Stevenage) on the first experimental 998 c.c. twin VincentH.R.D. This was done in perfect safety owing to a clear road, and to the exceptional road-holding and braking qualities of the machine.

Last summer another mechanic and I used frequently to take a pair of racing 500s to the Watford By-Pass at daybreak where we could run neck and neck for more than a mile without silencers— any lorries being clearly visible as they approached from side turnings. This road testing is essential because of the necessity for silencers at Brooklands.

Wishing the IVIOTOR SPORT every success. I am, Yours etc.,

P. R. MARIvER. Wrexham. *

ON ACHIEVING HIGH PERFORMANCE

Sir,

I very much enjoyed Ir. Boddy's article " On Achieving High Performance" in the March issue of your most interesting journal.

Mr. Boddy made a passing reference to the " Salinson " car. It has surprised me to note that during the five years or so of my reading MOTOR SPORT so little has been said about this marque.

Up to a year ago or thereabouts I possessed a 1927 G.P. Special which appeared virtually to be a "San Sebastian" model sans compressor. The G.P. Specials and San Sebastians were vastly superior to the ordinary sports Salmsons and even to-day are right up to date. Look at the specification :

Twin o.h.c. ; directly operated valves ; hemispherical heads ; tubular con-rods ; ball and roller main bearings ; four speed close ratio box ; Rudge wheels ; 12 volt lighting, etc. My Salmson weighed 12i cwt.-1,100 c.c. A trifle different from the modern method of loading up this capacity with upwards of one ton I I do wish some modern manufacturer could be

persuaded to produce a low priced vehicle of similar power-weight ratio—I suppose it is a forlorn hope.

My Salmson was really effortless to drive-1,500 r.p.m. per 20 m.p.h. in top gear-3.99 : 1 ; third was about 41: 1. Second about 7: 1 and bottom 11: 1. Cornering was marvellous—solid back axle—she went round as though on rails— far, far better than the very popular 750 c.c. sports-cars of to-day.

Incidentally the chassis was what you would refer to as of the " indiarubber variety" (vide "Rumblings" p. 141) but that, far from being a drawback, appeared definitely to help roadholding.

I must finish by offering my congratulations to you on your ex"ellent journal. I am, Yours etc.,

N. A. SMITH. Woodlands, Trent Vale,

Stoke-on-Trent. [Mr. Smith is obviously an enthusiast of the right sort. We, too, regret that so many good motors have passed. The H.R.G. seems to have something of the Sammy's power-weight ratio-1/ litres and under 15 cwt. Incidentally, the double-cam Salnason was written-up extensively in MOTOR SPORT in its day.—Ed.] Sir,

I must congratulate you on the improved form and paper in which MoToR SPORT is now published.

I have taken your paper in. for some two years, and must say that it is the most interesting motor paper which I have struck, as the reading matter is very informative, and some of your comments refreshingly caustic. Incidentally, I must thank you for the misplaced compliment in describing my performance in the J.C.C. Rally as creditable, but I was not driving a Magnette such as you say, but a P.B. Type four-seater Midget, so perhaps I am a little nearer to earning that compliment. Although my brother makes the Alta and I have no connection at all with his business. For your information I ran one of his 1,100 c.c. unsupercharged four-seater cars for three and a half years in which I covered 52,000 miles of quick motoring. Although I had several petty troubles due to the car being somewhat experimental in 1933, I enjoyed this period very much, earning nine cups etc., in sports-car events. This car did over 31 m.p.g. (allowing for speedometer error) on all the petrol I bought, climbed the highest Alpine Passes, and did a timed 83 m.p.h. flat out not long before I sold it. Its only real snag was the

mechanical noise at low speeds due to it being fitted with the old type gear driven camshaft instead of the present chain drive.

I am not mentioning this to give my brother's car a cheap advertisement, but simply for your information, as you have probably not been able to obtain much in the way of data on his cars.

Unfortunately, these are now rather too expensive for me, but I am so far very pleased indeed with my P.G. Midget, which combines an excellent performance with extreme docility. I am, Yours etc.,

C. E. TAYLOR. * * *

Claygate.

THE WORLD'S FASTEST TOURING CAR

Sir,

I have read with interest your article in the April issue Of MOTOR SPoRX" The World's Fastest Touring Car," describing the 5.4-litre supercharged Mercedes-Benz.

I think undoubtedly it is one of the finest cars in the world, but I was very surprised to see it stated " . . . and, fantastic as it may seem, a speed of no less than 108 m.p.h. was attained on a long, straight, level stretch, which is almost equal to a German Autobahn. One hundred miles per hour was also attained on another quite different but shorter stretch."

This does not seem to me at all fantastic and certainly does irot merit the title " The World's Fastest Touring Car."

My Type 57 Bugatti with an open body will do 110 m.p.h. and will run up to 100 or 105 m.p.h. on almost any road and in an incredibly short time.

The Type 57S Bugatti with an open touring body will comfortably do 120 m.p.h. These cars, as is probably well known, are not supercharged.

Incidentally the Type 50 4.9-litre supercharged Bugatti .first produced in 1930 is easily capable of 120 m.p.h. I am, Yours, etc.,

ERIC GILES. 2, Queen Street,

Mayfair, W.1. * * *

SLEEVE VALVES

Sir, I read with interest Mr. R. P. G. Jones's letter in your April issue on the merits of the sleeve valve, in which he suggests motor-racing as a means of developing this type of engine. I can't resist asking, at this stage, why develop it at all in this manner ? This may seem at first glance

to show a rather negative outlook on my part, but in view of recent developments with other, and to my mind, superior types Of gear valve, further development would appear to serve no useful purpose, in the automobile field at any rate. The two chief snags about a sleeve valve racing engine, and I note Mr. Jones appears to have in mind the small high revving type of engine as his references to the E.R.A. " R "Type Midget, Austin and Frazer-Nash show, in which these snags would be aggravated, are :

(1) High reciprocating weight and consequent high inertia stresses.

(2) Poor thermal conductivity. With regard to (I) there seems to be no means of reducing the reciprocating weight below that of a corresponding carefully designed D.O.C. poppet valve engine, in which the reciprocating weight consists merely of the valves, valve operating pistons and a portion of the

valve springs. Point (2) appears to be almost insuperable, as in order that a sleeve valve work satisfactorily an adequate oil film must be maintained around it. Ricardo and others have shown that Considerably more than 50 per cent. of the heat is dissipated from the piston crown via the piston rings to the cylinder wall. The extra oil film round the sleeve would effectively stop this path of heat dissipation.

The only point on which the sleeve valve scores (from the purely racing point of view) is the avoidance of the local hot spot caused by the exhaust valve in a conventional poppet valve engine, and the limiting factor of maximum power output. I have before me a B.H.P.-R.M.P. curve for a 247 c.c. air-cooled singlecylinder four-stroke running on 65 octane fuel and developing 17i b.h.p. at 6,000 r.p.m. with a fully silenced exhaust, the B.M.g.P. is 165 lb. per .sq. in. Yes, quite right, the Cross Rotary valve engine. It is so well known that a detailed description would be superfluous. I will only say that the engine derives its remarkable performance from a high compression ratio made possible by careful attention to cooling. e.g., use of a IT alloy linerless cylinder, 12 m.m. plug, and above all by the elimination of the local hot spot referred to in the previous: paragraph. Also reciprocating weight is reduced to the absolute minimum for a reciprocating engine, i.e., piston assem

bly and part of the con-rod. I would respectfully suggest that Mr. Jones examines its capabilities thoroughly before he starts developing his sleeve valve racing engine. Lest it be thought that I hold brief only for the Cross engine it is well to note that an engine fitted with an ingenious rotary valve system is running as 0, commercial proposition. I refer to the ninecylinder axial type engine developed by the Bristol Tramways and Carriage Co. Ltd., which shows much improved performance curves when compared with a corresponding in-line engine with normal valve gear built by the same firm. The Aspin engine recently described in the motoring journals also appears to be of

the rotary valve type, but no performance figures are available to the general public at the moment. This applies also to the rotary valve two cycle engine, the Cuddon-Fletcher, for which powers of up to 400 b.h.p. per litre were anticipated. It is also interesting to note that the Itala rotary valve engine was quite successful in pre-war days.

As regards my own pet theory as to the future form of racing-car engine, I incline to a rotary valve multi-cylinder two cycle engine with piston controlled exhaust ports (incandescent part bridges may prove a snag but the difficulties of cooling a rotary exhaust are great and liquid cooled bridges could be used). Liquid cooling would Of course be used, ethylene glycol possibly. The engine would be blower fed and positively exhausted (ambiguous !) by a centrifugal fan if the increased power warranted this complication. Additional cooling would be provided by an oil jet spraying the underside of each piston crown during the firing stroke (an idea due to Mr. Cross) and the lubrication would be of the dry sump type. Of course if a suitable injection pump could be developed, and I rather doubt it, the engine would be of the C.I. type on the lines of the Junkers Jumo, but of course with a rotary valve instead of double pistons. 1..1p to the moment the two-stroke has received little development for racing but some phenomenal power outputs have been attained from this type of engine. The straight eight Duesenberg in '27 gave a B.M.E.P. of 110 lb. per sq. in. from a normal blower fed bottom scavenging engine fitted with a rotary delay inlet valve, and the six-cylinder 11-litre Zoller showed promise until the untimely death of the designer in '33 put an end to further development. This engine was of the blower fed end to end scavenging double piston type, and though it never raced was reported to have achieved 145 m.p.h. in practice

In the motor-cycle racing sphere the 248 c.c. D.K.W. has proved invincible in its class during the past two seasons and develops approximately 115 b.h.p. per litre in road-racing trim. A 500 c.c. edition is emerging from its teething stage and will be watched with interest next season. It is well known that Freddie Dixon is pinning his faith on a twostroke for his latest project and if he is as successful as he has been in the past I shall have ample cause for rejoicing !

One further point, I notice Mr. Jones in his engine performance table classes the Frazer-Nash-Shelsley model with the Bristol engine as a high performance engine for continuous use. I would be interested to learn for what period a Shelsley model would develop its reputed 112 b.h.p. (assuming that the chains didn't break of course). I am, Yours etc„

IAN GORDON Macr.ton. Birmingham.

CHANGE OF ADDRESS

The London Showrooms which we took in Grosvenor Street to launch the FrazerNash-B.M,W., which was in those days comparatively unknown, have now been vacated by us.

Now that the sales success of the Frazer-Nash-B.M.W. is, generally speaking, an accomplished fact and we have a number of the best known agents in this country acting as Distributors, it was felt that we could safely relinquish these London showrooms, particularly as it will be appreciated that difficulties existed in the way of appointing London Distributors, especially as we ourselves with London showrooms would be in direct competition with such dealers.

The position has been solved very satisfactorily in that L. C. Bingham; Ltd., have taken over our previous showrooms as their new premises, and have been appointed by us as Joint Distributors for the Metropolitan Area for Frazer-Nash-B.M.W. cars.

Mr. L. C. Bingham and his other directors, including the Marquis de Belleroche, Are very enthusiastic about the future of the Frazer-Nash-B.M.W. and we are confident that --anyone calling will meet with every assistance. We are, Yours faithfully, A . F. N Lthirrup. Frazer-Nash Cars, Falcon Works, London Road,

Isleworth, Middx.

HIGH SPEEDS ON THE ROADS

Sir, May I take this opportunity of assuring Mr. jarvis, and his doubting friends, that high speeds are very possible on the roads in England. On my last two cars, a 41-litre " Le Mans " Bentley, and a 41-litre supercharged two-seater Bentley, I have touched the 95 m.p.h. mark almost times without number. Both cars did over the hundred mark on the road while I had them, and the following few instances may interest your readcrs, though they are not the only road.. e these cars did 100 m.p.h. on the o The best speed on the " Le Mans" was 106 m.p.h. on the Al., with my wife and I in front, my mother-in-law in the tonneau, and a cabin trunk on the carrier. The best effort was with four up, three suit cases, and the same cabin trunk. We then did 102 m.p.h. on the same stretch. The best speed on the " blower" was 117 m.p.h. on the Oxford By-Pass (this is a speedo reading really as the rev counter needle was over the end) with my wife and I up. On another occasion we cruised at over 100 m.p.h. for two or three miles on the Newark to

Lincoln road. Mr. Jarvis's friends would be as sur

prised as I was at the most ordinary piece of straight road required to do over the hundred mark on the " blower" Bentley. All these times are verified by witnesses in the car, and I would like to add that McKenzie's Garages Ltd. were responsible for the attention of these cars. I have no business connection with this firm. I am, Yours etc., "

BUSTER" BARING.

N.W.3.