Motordom

Southland Times, Issue 25312, 15 June 1935, Page 16

Motordom

News and

Notes.

'OF GENERAL INTEREST / ON THE ROAD AND ON THE WING. THE LATEST HAPPENINGS. Latest Publications. In the “Vauxhall Motorist” for April A. T. Stewart says that not so long ago caravanning was looked upon as the pastime of cranks. Nowadays it is the considered opinion of all those who have, enjoyed the experience that life can offer few more vidid joys than a caravan tour through beautiful scenery. O. V. Holmes is also a seeker after thrills in the open air, but he finds his enjoyment in an aeroplane. It is In fhe “Sports Car” for May that he enthusiastically describes the £lO5O Falcon equipped with a D.H. Major engine. This aeroplane has Miles flaps, brakes and an electric starter and lights. It is very easy to land, and is undoubtedly a very suitable machine for the private owner who requires a fast air saloon. Driving Test Concession. Representations made to the Ministry of Transport by the Automobile Association have resulted in an important concession to overseas motorists driving in Great Britain. The A.A. has now been officially informed that visitors in possession of an international driving licence issued by a competent authority, will be exempt from the British driving test. Thousands of motorists visiting Britain with their cars, or intending to hire a vehicle to drive themselves will benefit by exemption from this regulation. The International Driving Permit serves as a driving licence in all countries adhering to the International Convention, but is not valid in the country issuing it. Coventry Buys More ’Buses. Coventry Corporation, acting on the recommendation of the Transport Committee of the City Council, has placed an order with the Daimler company says our English correspondent. The new vehicles will supplement a present fleet of 23 Daimler ’buses in use by" the corporation, and will mean a considerable augumentation of the city’s transport facilities. They are of the six-cylinder A.E.C. heavy'oil type, with fluid flywheel transmission. The contract, which was keenly competed for, will be to the benefit of local employment. The tender submitted by the Daimler company was not, it is stated, the lowest, but it was their experience, gained from the existing fleet, of the excellent performance of the Daimler fluid flywheel, which was the deciding factor in the corporation’s choice. A Popular Light Six. From its very introduction the Vauxhall Light Six was a marked success, and no one can have failed to notice the numbers of these cars on our roads; yet it is little more than eighteen months ago since the model was first produced. For 1935 the basic design and style of the car are wisely retained, but some important alterations are made, consisting principally of the fitting of independent front wheel suspension, the lowering of the frame, and the moving forward of the engine slightly so as to give more room in. the body. Always the Light Six Vauxhall, and in particular the 14 h.p. model—there is a Twelve as well—has made a very favourable impression by reason of its easy, lively performance. This is on account of an engine which develops useful power propelling a car wherein the keeping down of weight within reasonable limits has been carefully studied. The latest model is a little heavier than its predecessor, but in no way has performance been lessened; maximum speed remains more than adequate, and the acceleration is distinctly good, as the figures indicate. The all-important top gear figures show up very well for a car of medium engine size. Battery Efficiency. A motor car battery is not nearly so efficient when it is cold than at normal temperatures. Although it may be fully charged, it is not capable of delivering its maximum power on days, (and nights,) when the thermometer is low. This is unfortunate, because it is in the winter-time that the battery is needed much more than when the days are long and warm. In the winter time, lights, are used more; engines take longer to start, and great is the consumption of current. Nothing drains a battery more effectively than an engine that is j slow to start. Batteries may be to a large extent preserved for their important jobs of lighting the way, and of starting the engine, _ (and of sounding the horn,) by the simple procedure of draining out the old engine oil, and refilling with the correct winter grade of .oil. A summer grade of oil is too heavy for winter use. It clogs the cold engine, making the job of turning it over to start a difficult and frequently a lengthy one. But an oil that is fluid at low temperatures permits an easy and rapid turning-over of the engine—an. essential to a quick start in the cold. With such an oil as the correct winter grade of Mobiloil, there is no danger that the oil will be too “light” once the engine has thoroughly warmed up. Ordinary light oils may give easy starting, but there their advantages cease, for they are apt to break down at high speeds and temperatures. The winter grades of Mobiloil, however, have a double-range quality, and do not thin out unduly even at high engine heats. They give thorough protection at all times. The use of such oils throughout the winter months saves the battery at a period when it is most needed. - ’ British Aeronautical Achievement Behind the sale of c Gipsy Major engine No. 5999 lies the story of an achievement in the history of British aviation for which the de Haviiland Aircraft Company is responsible. Messrs General Aircraft Ltd., the well known manufacturers of Monospar aircraft, were the purchasers of the thousandth Gipsy Major engine jn March. The production programme of the de Haviiland Aircraft Company at Stag Lane, Edgware, is advancing month by month, and the present Gipsy engine programme is at the rate of thirteen 130h.p. Gipsy Majors and seven 200-h.p. Gipsy Six per week; the production of the latter engine was increased to eight engines per week from the beginning of April. The two hundredth Gipsy Six engine was delivered recently to Messrs, Jersey Airways as a spare engine for one of their fleet of D.H.86 Express Air Liners. The reliability of Gipsy Aero Engines is-being demonstrated hourly; new standard of production and output the engine factory of the de Haviiland Aircraft Co. at Stag lane—the home of the Gipsy engine and where the de Haviiland controllablef-pitch airscrew is being manufactured—has been organized with such meticulous care that maximum output is being Obtained with the high-

est degree of reliability and safety and with the minimum loss of time and energy. Since the production of the first Gipsy 1 engine in 1928 the total number of Gipsy engines manufactured th date has reached the neighbourhood of 4000. Fine Motor Cycle. Harley-Davidson motor cycles earned an enviable u reputation in the early days of motor cycling in this country, and hundreds of back-date models are at present still doing excellent service on Dominion highways. At the beginning of the depression dealers ceased importing the machines owing to the high cost, and so for over three years motor cyclists in New Zealand could not acquaint themselves with the improvements being made both in design and performance. Recently, however, an Invercargill rider placed an order with Messrs Tapper’s Limited for a 1935 10-12 h.p. Harley Devidson and this machine is now on view at the firm’s premises in Dee street. The model is a splendid example of American motor cycle production, and is beautifully finished in Egyptian ivory and regent brown colours. The motor is of the air-cooled, four stroke cycle type with side by side'valves and detachable cylinder heads. It has three speed transmission with gear shift lock and a multiple dry disc clutch operated by foot. The drive is given by a Duplex extra heavy roller chain for the front and the rear chain is an extra heavy single roller. The tanks are of the saddle type and the main one has a capacity of 22 pints, while the reserve holds 8| pints of petrol. The frame is low set and of great strength with the front forks cushioned with coil springs for comfortable riding. The wheels are interchangeable and large size balloon tyres give great comfort which is added to by the specially sprung saddle. The electrical equipment is of the latest type and the cycle carries a dashboard similar to a car, on the handlebars. A special lock on the front forks makes the machine theftproof. A speed of 100 miles an hour is possible with the cycle. Manufacture of Safety Glass. The announcement that an Australian company has acquired the patent rights for the manufacture of non-splintering “safety”. glass in this country is of special interest to motorists, writes a journalist in an Australian paper. This glass is of a unique character, inasmuch as it is quite different from the laminated type of safety glass,'for when it is broken under the force of a direct blow it disintegrates into a mass of tiny pieces, resembling somewhat ordinary bath salts in appearance. What is more, these particles are as harmless as bath salts, for they can be handled with indifference, and even rubbed between the fingers or palms of hands without cutting or piercing the skin. The advantages of such a product over ordinary plate-glass windscreens are too obvious to need* stressing to motorists, for there is no fear of the occupants of a motor vehicle being cut or injured in any way by flying fragments of glass 'in the event of an .accident. Another advantage of this new glass, which is to be marketed in the Commonwealth as “Tarzan” safety glass, is that it does not discolour with age; in fact, it is normal plate-glass, specially electrically heat-treated, and there is nothing in the product to discolour. “Tarzan” glass is more flexible and stronger than plate-glass. An interesting test is related in the “Dunlop Bulletin” in connection with this product when first marketed in England in 1933. During experiments to ascertain the degree of toughness of the new product, a steel ball, weighing nearly 21b, when dropped from 9in, broke an ordinary sheet of plate-glass, whereas it was found necessary to increase the drop to 156 in before the sheet of “Tarzan” type of toughened glass broke, and then it simply disintegrated into innumerable small particles. It is reported that the retail price in this country of an aver-age-size windscreen made of this safety glass will be slightly more than £2. In the interests of safety, there is litjle doubt that this new product will appeal greatly to Australian owners of cars and commercial motor vehicles fitted with ordinary glass windscreens, for there are few motorists who do not appreciate the . dangers of plate-glass splintering in the event of an accident. THE VALVE QUESTION TECHNICAL POINTS. “FLUID REFRIGERATION.” It is well known that cars of approximately similar design often show variations in performance far greater than would be expected and, moreover, that cars with deficient performance are often insensitive to changes in inlet manifold arrangements, camshaft timing and so on, says Laurence Pomeroy, iun,, in the “The Sports Car.” There is, of course, a large number of possible explanations for this, but I believe that in many instances the cause lies in the lay-out of the engine in respect of heat flow. An Australian Aboriginal, intelligent enough to design an engine from information derived from text-books of the more academic class, would probably do all in his power to see that an internal combustion engine ran as hot as possible, and would probably completely lose faith in Western civilization as a result of the inferior performance he would obtain. It is indeed becoming ever more obvious that one of the vital considerations of high-performance engines is the. maintenance of the whole of the combustion chamber at the lowest possible temperature, a matter to which one cannot make any reference without mentioning the name of Mr R. C. Cross, who, in his experiments with the Cross oil-cooled valve and the Cross rotary valve has done so much to call attention to this matter. Quite apart from indirect benefits, such as improved reliability, fuel consumption, absence of sparking plug troubles and so on. the directly measurable effects of cool combustion on engine performance are very, considerable.

Taking the case of an unsupercharged type, experiments have shown that an h.p. gain of at least 30 per cent, should be obtained over the best of what is now normal practice, and this should result in an output of around 65-70 b.h.p. at 5000 r.pm. from an 1100 cc. engine running on straight fuel. It is, therefore, reasonable to expect ' from these figufes that a production engine will give nearly the same performance on ordinary fuel as the same type would now give when tuned for the 500 Miles. Race running on alcohol fuel. We often see racing fuels described even* in the technical press as “liquid dynamite,” which, however, is a completely inaccurate description as the explosive properties of racing fuels are much loweS than those of ordinary fuels. What the racing man does in

his pit stop is, in fact, to pour into the tank “fluid refrigeration” which at the same time possesses explosive properties, if used in quantities, about 100 per cent, greater than would be required for petrol. Such a rise in consumption obviously precludes the use of these fuels foi touring car engines, and with them the internal cooling which they give. From this fact, I may be pardoned for making the statement that on highoutput production car engines, a designer is “driven back” to the use of water as the sole cooling medium, and to achieve cool combustion under these circumstances involved an intensive study, not only of exhaust valve arrangements, but also of sparking plugs, pistons, cylinder head and cylinders. These all form part of the combustion space, and it cannot be said that any one of them is inherently more important than the other, so I propose to give a very brief description of the principles which have to be followed in designing each of these components so as to ensure that they run at the lowest possible temperature. It is not so generally known as it should be that the exhaust valves, of the modern engine, when running under full throttle conditions are always over red heat, and on some engines achieve a temperature approximately equal to that obtained at the far end of a gas fire element. It is, therefore, really quite astonishing that it is necessary to have a sparking plug to fire the charge and, indeed, if the temperature rises sufficiently the plug does cease to be necessary. This can be practically demonstrated by switching off the ignition and holding the throttle open, when the engine will go on firing quite regularly for a long time. . I was recently present at some tests of a 2-litre engine which would hold 30 h.p. on the test bed with no ignition except the hot exhaust valves. To reduce the temperature of the valves by orthodox means, it is essential that water should be brought as near as possible to the valve seats ana taken as far around the seats as is practicable, a point on which many engines show up badly, particularly where two exhaust valves operate adi jacent to one another. In addition to the valve seats, the guides take away a large proportion of the heat and should, therefore, be made as long as possible, and water placed round the guides as well as round the valve seats. The head of a valve has to be considered from two different angles. In order to keep the temperature down to the lowest point, one would normally use a very thick valve so as to assist the heat flow through to the stem and out through the guide, and also from the centre of the head to the valve This, however, is a scheme which cannot always be applied in practice, as on many engines there is considerable distortion of the cylinder block near to the exhaust valve resulting in the exhaust valve seat going out of round and a clearance developing between the seat and the valve. Such an occurrence is quickly followed by the retreat, in bad order, of the exhaust valve from the engine to the scrap heap with a burnt-out seating. This can be best cured by making a. very thin flexible valve which will conform to the shape of the valve seat when this has ceased to be the pretty picture it was on the drawing board. Thus, one can summarize the exhaust valve position by saying that the primary need in order to maintain the .lowest temperature is that there should be “water, water everywhere,” and secondly, that the shape of the valve head must be considered in relation to the cylinder head or block. It is worth while, however, pointing out that whilst the exhaust valve, by getting overheated, causes the sparking plug, Piston and cylinder in turn to give trouble, it is possible for the process to originate the other way round; for example, badly located sparking plugs or the use of the wrong type may set up a number of things resulting in the exhaust valves becoming overheated. I have gone into this question of exhaust valves at some length because they are usually the first items to give trouble when compression ratios are raised, or supercharging at fair pressures is employed, and I have pointed out the essentials of seeing that they do not get overheated. Further advantages can be obtained by reducing the temperature to what can be only termed sub-normal in the light of present practice, a very practical method of doing this being to employ a hollow valve stem and head, and to run partly up the valve stem a pipe which feeds oil under pressure into the very middle of the valve. This is a patent of Mr R. C. Cross, which, as I have seen, enables a 9 h.p. saloon car to climb a hill on third gear which is sufficiently steep to reduce an exactly similar car with normal valves to second gear. The car with oil-cooled valves was running on a compression ratio of 8 to 1, yet could be driven to an absolute standstill on top gear without “pinking” when using No. 3 petrol. Despite these good results, there are those, Mr Cross amongst them, who remember the Elder Cato’s delenda est whenever they think, not of Carthage, but of poppet valves, and it does look as though we shall shortly have certain engines operating on rotary valves of one type or another. So far, attempts at eliminating the poppet valve have been unsuccessful (and I think that there is plenty of life in the old dog yet), whilst the rotary valve is in some ways difficult to apply to multi-cylinder engines. As the stress of competitive performance grows more and more intense, we are, therefore, likely to see a variety of policies being followed by manufacturers in respect of exhaust valves, including the intensive study of cooling the orthodox type, the use of internally oil-cooled valves and, by the bolder spirits, the total abolition of the poppet vaive and its substitution by the rotary valve. In any event, there is no doubt that the thought and research which are now being given by manufacturers to this problem will result in next year’s cars running with higher compression ratios and developing higher h.p.’s than have hitherto been obtained, whilst using petrol of a lower grade than is necessary on the present-day car. May I say that I am attempting to put these problems forward as they are viewed by the engine designer. To him, the solution of such detail problems is of vital importance. He knows that in the design of high output engines, effort can never be relaxed, and that in the words of Pericles, “You must not shirk hardships; if you do, you must alsp abandon the quest of honours.”

MOTORING HOWLERS The modem child is often an authority on motors and knows a great deal about their workings, but sometimes his knowledge is fragmentary. It is.not surprising, therefore, to -find mat m Latest Howlers, Mr Hunt, the compiler, has included quite a number ot mistakes of interest to motorists. Mr Hunt avers that so far as he can find out, every howler he prints is genuine, and. he has seen the actual examination papers of some of the most amazing. He vouches for the authenticity ot “The Yellow Peril is a racing . car, which reads more like the creation of a professional humorist than an unconsciously humorous child, and many motorists may agree with the youthful essayist who wrote Non-productive wages are wages paid for illegitimate work, e.g. wages paid by a Chicago gangster to his gunmen, and money paid to policemen for summons through bicycle lamps going out.” It seems as though that child believed that policemen should be engaged in more important work than catching unintentional offenders against rules and regulations.

DRIVING TO-DAY SOME RULES TO OBSERVE. DRIVING TESTS DISCUSSED. With registrations of automobiles now equal to those of the pre-depressidn peak period and the prospect in the immediate future of extensive replacement of older-model cars by modem high-performance types, traffic authorities in this country are searching diligently for some means to relieve traffic congestion and (of still greater moment) to check the alarming increase in highway accidents in which motors are involved, says the motor writer in The Bulletin.

The matter is one of national importance, and any plan whereby damage to life and property can be lessened should be worth a trial; yet, as every experienced motorist must realize, legislation, however drastic, cannot alone achieve the desired benefits. The crux of present evils lies in the behavour and acts of individual motorists.

The position can be viewed in true perspective only after a careful study of existing machinery for regulation and control of traffic. Whilst details may vary in each State, the principles involved in contemporary Australian legislation are identical. Driving Tests.

When a citizen decides for the first time to operate a car on the public highways he is required, as a first step, to pass a practical test of more or less comprehensive character before a license to drive is issued by the traffic authorities. Then, on being handed the license and a “book of words,” he is, in the eyes of the law, a . fullyqualified driver, conversant with the Act and numberless regulations, even though they have been gazetted after the license was issued. In these initial stages of a driver’s career two weaknesses in present methods are at once apparent. First, except for a casual eyesight test, no effort is made to discover if the applicant for a driving license is in a suitable physical condition to handle the car in a safe manner or to carry out the regulations. Secondly, every Holder of a license is presupposed to know everything and do everything correctly according to the “book.” But though these defects in control are obvious, it seems almost impossible to improve matters save at a prohibitive cost. . On the first count, that of physical fitness, the eyesight test involves reading a series of letters, placed directly before the applicant, the percentage of failures being very low. There is no test for colour-blindness. Yet in some cities drivers must obey automatic signals involving the use of coloured lights.. Many motorists are colourblind. Again, some individuals are affected by “tunnel vision,” their field of vision being restricted to objects directly ahead. Defective Eyesight. Any driver with normal sight should be able to look through the windscreen and, without altering the focus of his eyes, detect major movements of objects on either side thus giving a more or less effective field of vision of up to 180 degrees—some people have an even wider range. Innumerable accidents have happened to drivers afflicted with tunnel vision simply because they were not aware of the disability. In this regard a simple test can be made in order to determine exactly one’s field of vision. Select some object immediately in front, and look at it intently, then slowly raise the hands on either side of the head, keeping them approximately two feet from the body; the greatest angle at which both hands and the object selected can be plainly seen gives the effective angle of vision, which, for purposes of safety, should never be less than 140 degrees. Of almost equal importance to perfect vision is the faculty of estimating with precision problems involving distance and speed, statistics proving that the greater number of roadside casualties are primarily due to failure in this connection. Particularly does this apply to a motorist who, after some years at the wheel of an old-type car, takes over one of the later types, in which acceleration and maximum speed are vastly superior, and in which the engine is quieter. Individual Character. In respect to the legal fiction that drivers have an encyclopaedic knowledge of the redes and regulations of the road, legislation cannot possibly transform the fiction into fact. The amount he knows about his duties and responsibilities depends solely on the character and temperament of the man at the wheel. . After almost 30 years, of motoring, the writer's considered opinion is that all highway accidents can be put in two groups—those due to road-hoggishness and those due to lack of experience or knowledge on the part of the driver. In dealing with the offenders of the first group, laws and regulations, while powerless to prevent accidents, are salutary insofar as they provide penalties and tend to discourage repetition; but the only cure for limited knowledge is a scheme of graded licenses or a comprehensive educational campaign by traffic authorities, the cost of either of which would be prohibitive. It is possible, however, to offer helpful advice to motorists who are lawabiding citizens and who desire to protect themselves, their passengers and other road J users. Overconfidence.

For a little while after the motoring novice has secured his license and is thrown upon his own resources, he is, as a general rule, particularly careful, and concentrates whole-heartedly on the safe manipulation of his car. He rightly assumes that the law of selfpreservation, both for his car and for himself, demands full-time attention when at the wheel. Sooner or later, however, there comes a time when he emerges from the stage of intense conscious concentration into the less anxious condition of semiautomatic control. At this particular time there is grave danger of overconfidence, and the novice is quite likely to attempt some manoeuvre that he cannot complete successfully. While this class of driving can scarcely be called discourteous, yet the fact remains that overconfident novices are responsible for a number of thrills and close calls-that older and more staid drivers could well do without. Now comes the case of the experienced driver, who should have better sense that to indulge in stupid and potentially dangerous practices. Where the motoring fraternity composed entirely of people of equable temperament and perfect manners—granting, of course, average skill—safety-first tactics would be automatically applied, and, if accidents and irritating incidents were not altogether eliminated, they would be lessened to a very great extent. Unfortunately, this ideal condition does not exist, and the number of impetuous and short-tempered drivers is increasing every day. Of course, some men are inherently bad, and they will persist in despicable actions while at the wheel until someone drags them from their seat and gives them a thorough hiding. Moral suasion and logical arguments in such a case are equally futile.

On the other hand there is a huge army of motorists who, otherwise quite rational, occasionally irritate and inconvenience other road-users, and it is to these people an appeal is made. Greater tolerance, especially by city motorists, must be shown than at present. The fact that one is in a huury is, no excuse for an exhibition of bad manners; other people, though better

behaved, may be in quite as great a hurry. If you are waiting for an elevator you would not dream of pushing in front of those already at the door; and yet at tram stops and traffic blocks one regularly sees drivers forcing their way up to the head of the queue. Is it the absence of fear of personal violence that allows this kind of action from the driving seat, but never in a crowd of people? Whatever may be the reason, it is to be hoped that those who make a practice of this type of driving will in future exercise more restraint and set a better example. Irritating Tactics.

Another dangerous practice is that of speeding up when being overtaken. The mere fact that you have been caught proves that the other fellow is travelling at a higher average speed. He may or may not be driving too fast, and he may be in a cheap flivver and you in a costly sedan, but whatever the case he gives you no excuse for complicating matters. On the other hand, should you find it necessary to pass another be sure of the state of traffic ahead. Await a favourable opportunity; and after passing keep up the same speed until well clear before pulling in front Don’t slow down at once and make someone swallow your dust—it’s not good manners. Approaching intersections always reduce pace sufficiently to be able to stop within the distance of your vision, and remember the man on the right has the right of way. Briefly, this means that, when two vehicles are approaching an intersection or converging courses and by reason of their speed and direction may be expected to collide, the man on the driver’s left must give way. It must be admitted that in most instances there may be some doubt as to who would, in normal circumstances, arrive first at the intersection, but there must be no indecision, the correct attitude being invariably to allow the man on the right to pass ahead. , Blind Spots.

Possibly one of the gravest risks one may take Is to overtake another vehicle on a blind spot, whether it be on the crest of a hill or on an acute bend. Here the offeding driver is sometimes lulled into a sense of security by reason of the fact that, except for the car ahead, the road seems deserted; but ’ the motorist should be warned that, however great the hurry, he must, in the interests of safety, sit in behind until the road ahead is in full view.

In connection with night driving there are still a number of motorists who show little consideration for others in the method of using their headlight switches. The practice of switching of or on when right under the nose of an approaching car is not only discourteus, but fraught with danger to both parties. If the headlights comply with the requirements of traffic regulations it is a much safer practice to keep them on when passing. Slow down and watch the inside kerb, and keep as far towards your correct side as possible. Then there will be no danger or inconvenience whatever. Should lights be switched off at close range the exact location of the approaching car, as well as all other objects on the road, becomes largely guesswork, and a source of grave danger to every road-user in the vicinity is created. The final matter in which drivers might well show greater consideration is in the application of brakes. Although brakes on all four wheels are practically universal in modem cars, there are still on the road a large number of older models not so equipped. Drivers of these older cars are hard pressed to dodge trouble if one happens to jam the four-wheel set hard on when immediately in front; so keep a sharp look out and give as much room as possible. MIDGET RACERS THE DIRT TRACK CARS. INTERESTING PERFORMANCES.

Wherever owners of sporting vehicles gather together over a pint of this or that you will hear the phrase “power-weight ratio” being freely bandied about. Power-weight ratio is a nice well-informed-sounding term. This is a story of power-weight ratio, chiefly, says Norman Ruck in an English motor monthly discussing the latest midget dirt track cars.

Originally it was my intention to prove, by a species of mathematics known as Simple Proportion, that the latest type of midget dirt-track car represents power-weight ratio in its highest known form. My reasoning and mental arithmetic went something like this:—

Q. —If these midgets (with a small m) have any superiors in this respect, what are they? A.—The Grand Prix cars.

Very well then. Now to approximate unscruplously: A typical Grand Prix car weighs 14 cwt. and develops 400 h.p. A representative speedway midget tips the scale at 4J cwts. and produces 60 h.p. Thus, 14 is to 400 as 4| is to—what? Five minutes’ figuring brought nothing more satisfactory in the way of conclusions than that Simple Proportion is not so simple as they make out. Though, frankly, I have a haunting suspicion that the big 'un wins. Power-Weight.

However that may be, it is obvious that when you harness 4J cwts. to 60 b.h.p., and in such a fashion as to sacrifice a bare minimum of foot-pounds in the transmission process, you do undeniably “ring the bell” so far as this power-weight business is concerned. Although these figures augur a vehicle which can hardly be devoid of interest, the average follower of the better-known forms of motor sport knows very little about the construction of these dirt-track cars. One reason for this is that he probably doesn’t regard them as cars at all, any more than the man who pedals daily to work sees any relationship between his Raleigh and the bechromiumed singlewheel contrivance on which trick cyclists divert the vaudeville public. A Miracle. ■< True enough, the midgets aren’t cars. They are motor-cycles on four wheels. It is a fact, I am told, that their weight is only twenty or thirty pounds in excess of that of the heaviest type of solo motor-cycle. What a miracle of weightparing that implies! Even my limited arithmetic enables me to realize that four wheels must weight twice as much as two. And it is reasonable —though apparently wrong—to imagine that a chassis frame capable of keeping four wheels in their correct relative positions would weigh more than a motorcycle frame. When questions of high power output per unit capacity are in debate, motor-cyclists are never slow to tell us that their engines are streets ahead of ours—so long as we refrain from fitting superchargers. (In which case they “won’t play.”) A study of the speedway car brings interesting evidence to bear on the subject. But before going further, it should perhaps be explained that the particular car on which calculations are based in this article is the J.A.P.-engined Gnat, sponsored by Jean Reville of Wimbledon, that leading authority on, and exponent of, speedway craft. There are, of course, a number of other types coming into existence in anticipation of the expected boom. But the Gnat has, I think, the distinction of being the first English midget to be built to the specification laid down by the Midget Car Speedway Association, of which specification more anon. A well-prepared , 998 c.c. J.A.P, engine of the type fitted to the Gnat produces an honest 60 b.h.p. on a‘ diet of special dope fuel. I don’t propose holding this up as a record, first be-

cause somebody would instantly correspond with the Editor , and call me a liar, and, secondly, because I don’t much care whether it is or not. Let it rest at this—l, in my ignorance, ken no better figure fpr an unblown 1-litre engine. If we are to assume that this output is singularly handsome, it is interesting to ask ourselves where all the power comes from. And having recently been priviliged to stand over a mechanic while he turned a racing J.A.P. inside out, I should know, I suppose. Yet it isn’t any too obvious. Stiffness. One thing which immediately strikes the student of contemporary car engine design is the care which the motorcycle designer takes to ensure the utmost rigidity everywhere. The crankshaft, of course( presents no difficulties: the inherent brevity of a V-twin shaft ensures the highest possible degree of

rigidity. The crankcase is a singularly massive piece of work, reinforced heavily on the drive side by radial fins. Designed to bear the brunt of a compression ratio of about 10 to 1, the conrods are of wide 1-section; and the contours of the big end merge into the rod in a very easy radius. The bigends run on large roller bearings and are lubricated under pressure through drilled oilways. The cylinder heads are notable for their beautifully hemispherical shape, made possible by the wide angle which the valves make with each other. The clean sweep of the ports and their crannies is also a joy to behold. The story doesn’t end there by a long chalk, of course; but a minute inside description of the 8-50 J.A.P. engine is not my purpose. (Incidentally, the description “8-50,” in connection with this unit, seems to cause a certain amount of confusion—it has frequently been wrongly interpreted as meaning

850 c.c. Actually it refers to rated and brake horse-power. The “fifty” was true several years ago. Since then the dynamompter has risen to new levels. But the name sticks.) Now may I take you back to the M.C.SA. specification for midget cars. The following are its requirements:— Engine limit, 1,100 c.c.; super-chargers barred; ground clearance, not less than 4ins.; brakes ’compulsory; _ wired-on tyres compulsory; exhaust pipes to extend beyond rear axles; wheelbase, not more than sft 6ins; diameter of wheels, 12ins (the last-named is not, I believe, to be rigorously enforced, as tyres suitable for a slightly larger wheel are easily obtainable). Although the engine limit is actually 1,100 c.c., I don’t think it likely that many people will take advantage of the full limit. A notable exception to this will be Victor Gillow, who raced his Rileys so effectively last year and has, I understand, even more ambitious

plans for the season ahead. Apart from this idol of the Crystal Palace “fans,” the indications are that the great majority of engines in use will be 998 c.c J-A-P.s. It will be noticed that there is no ruling on the question of front or rear drive. Having seen both in action I am convinced that the latter is infinitely superior for creating an illusionary impression of speed and impending death for all concerned; though this is not to say that the front drive has not the less important merit of being actually faster on the bends. . . In order to view this question in its right perspective it must be realized that the man behind the loudspeaker is under no obligation to mention actual speeds of races. To do so is, in fact, unadvisable, for speeds (let us be honest) have been ignominiously slow in the past; and even with the coming of the new types of regulation car, it would be optimistic to expect an increase of more than 5 or 6 iit-ph.