MOTORING

Nelson Evening Mail, Volume LXIV, 20 June 1931, Page 4

MOTORING

PETROL ECONOMY

CAREFUL DRIVING VALUE QUESTION OK SPEED Ei>\v motorists appreciate in full tlio important nitfiiom-e which speed and driving' methods in 'tenoral exert upon the amount of petrol consumed. Naturally. extreme, economy involves a. sacrifice in motoring comfort which few drivers countenance, hut, on the other hand, many people are certainly wasting petrol in ways which they could easily correct without appreciable loss of time or profit. Many persons believe thal, although fast travelling mpiires greater power, this is compensated by the rapidity with which the journey is covered. In this way they seek to prove that the petrol consumption should not be markedly -affected, but such an argument is quite fallacious, says an exchange. At any speed above .‘lO m.p.li. wind resistance and the power to overcome it both increases very rapidly. 'I bis means that the higher the speed the wider must the throttle he held open. The throttle, of course, acts merely as a tap regulating the amount of mixture drawn into the. engine. In reasonably level country the number of revolutions the engine makes in covering a certain journey is exactly the same whether the distance 'he covered slowly or quickly. .Fijom this argument it is clearly seen that, as the faster journey involves a bigger throttle opening, the petrol consumption will necessarily he higher.

If practical proof in this connection he needed it may be mentioned that in a series of tests carried out in England recently, it was shown that the mileage per gallon at 20 m.p.li. and 30 m.p.li. was practically the same, but at 00 m.p.h. it was halved.. These results may bo slightly modified in very hilly, country, because a higher average speed may enable certain gradients to he taken with a rush j in top gear which would otherwise I have necessitated changing down. Naturally, the use of a lower gear increases the engine speed ami more petrol is consumed. It is, of course, had practice to allow an engine .to labour pulling the car slowly uphill irr ‘top, hut, all the same, too frequent use of the gearbox causes Unnecessary waste of fuel. The careful driver must', endeavour to strike a happy medium between these extremes. Tiie next point is that Ihn speed should be kept ns steady as possible. The driver who is constantly accelerating up to 50 m.p.li., immediately afterwards having to brake heavily for a corner or oilier traffic. uses far more petrol than one who is content to plug along at more modest speeds. This is simply due to the fact that the A “Unique” Hot Water Bottle means sound sleep, refreshing rest —just that. And “Unique” lasts a lifetime.

power needed to atseelerato iho mass of (lie ear is much greater than that required lo keep it running at a sleadv rate.

Petrol also is wasted by a jerky action of the foot on the llirottlo. In some, cases throttle springs are unduly light, so (bat. on a rough road it is difficult to keep the foot steady without some, form of rest. An English expert staled recently tlqit it is a great pity that people do not make greater use of (lie band throttle control, because a steady setting is' far more economical Hum one which is constantly varying. When cruising on a inain road it will usually be found dial, having attained the speed required, the throttle can be closed slightly /without losing headway.. Use of the minimum throttle opening is economical.

AN 1832 MODEL SOUKTIiIiN’ MILKS AN HOUR! 'The following is an account of an early rim from Oxford to Birmingham in a self-propelled vehicle: — In the. year of grace 18112, upon the occasion of the Fair of St. Giles, at Oxford, an interesting vehicle made its appearance. It was propelled by steam, and attained the (then) stupendous speed of fourteen miles an hour. -’I have just returned,” says an onlooker, stili almost breathless with excitement, “from witnessing the triumph of science in mechanics, a steam carriage, travelling along a Hilly and crooked road from Oxford to Birmingham.”

“Hilly and crooked,” mind you! None of your can’t-stop runs on a tea-tray straight down the stairs. This triumphant vehicle Reeded power and skill indeed to take her up the winding route from Oxford to Birmingham. And nobly did she accomplish the run—at least, until the very last lap.

ESTIMATED SPEED “This truly wonderful machine,” says the onlooker, “is the invention of Captain. Ogle, of the Royal Navy, and Mr Summers, his partner, and is the first and only one that has accomplished so long a journey over chance roads, and without rails.”

! In those days there were, of course, no traffic P.C.’s, let alone police traps, | so that the gallant captain and his partner were free to let her rip. The onlooker, reckoning speed with the customary generosity of > tlic pedestrian, says: ’“The rate of going may he called twelve miles an hour, hut fifty or perhaps a hundred, downhill.” While we are holding our breath, however, we note with relief that she cjirried that wonderful invention, “the Break” (with a. capital B), “which places the whole of the machinery under complete control.” It must have been a grand sight to see them start from Oxford. Being the Feast of St. Giles, all the fun of the fair would be in full swing, but would lie bold up for this new wonder show. All the comc-lassies-and-lads of the neighbouring villages, mingled with the grave and reverend dons and eager students, would be thronging the streets to see and touch, or at least sniff at the snorting, fiery steed. “Care was, however, taken to make them understand the danger,” says our local correspondent, “and a passage being cleared, away went the splendid vehicle through that beauteous city, at the rate of ten miles an hour, which, when dear of the houses, was accelerated to fourteen.”

Every town tilling the route turned out in full force, with acclamation, for the event had been well advertised, “notice of the intended journey having been carried forward some days before.” »Sweet was the uses of publicity, but perhaps it was this very warmth of welcome on route that upset, by a fraction, the scientific calculations of Messrs Ogle and Summers. Perhaps the bills were a shade too hilly, and the winding lnnes too “crooked.” However it may have been, tlie marvellous machine, on entering Birmingham Town, developed engine trouble. “The supply of coke being exhausted, the steam dropped.”

THE NEW TOY But Birmingham was full of sympathy for this lame end to a sporting event. Assistance was required, “and willingly it was granted,” say.> the reporter. “The good people, on learning the cause, flew to the frame, and dragged it into the inn-yanl of the “Hen and Chickens.’ ” What a homely touch that sheltering title gives!

ON STARTING USUAL PRACTICE CRITICISED AN ENGINEER’S THEORIES When I first became acquainted with motor-cars (writes Mr J. Harrison, A.M.I.Mcch.E., A.M.1.A.E., in the “Autocar”) engine starting, especially on a cold morning, was something of an adventure. One opened the bonnet, tickled the carburettor, stuffed a petrolsoaked rag into the air intake, and wound the starting handle round half a dozen revolutions. After that, one switched on, withdrew the rags from the air intake, and, if all was well, tlie engine would start on an early swing. Even after the electric starter was invented there was the same ritual with tlio starting handle and petrolsoaked rag every morning, for the early electric batteries could not be expected to stand tlie strain of breaking down the gumming oil film that held castiron pistons when tlio engine was cold. When batteries grew so robust that they could be relied upon to start a cold engine without buckling their plates, the recognised starting procedure was as follows: One seated oneself in the driving seat, retarded the spark half-way, switched on, pulled up the strangler wire, and then stepped on the starter switch. This is still the method of the majority of car owners, even in these days of battery ignition. But is it correct? About five or six years ago no magneto could be expected to give a spark strong enough to fire the mixture until it had. attained a speed of at least 40 revs per minute, and therefore, of necessity, two or throe seconds lapsed between the time when the starter button was pressed and the instant when the engine bad attained a sufficient speed for the magneto to five the charge in the cylinders.

INSIDE THE CYLINDERS During Unit comparatively brief interval of time a number of things Tonsilitis .prevented by regular use of Brodie’s Kanalox, 4/- bottle. —Nees, Chemist, Hardy-st. Youth-0-Form Capsules not only reduce weight, but make you feel wonderfully fit. G/6. —Nnes, Chemist, Hardyst. Rheumatism combatted by dissolving uric, acid crystals with Mackenzie’s Mcnthoids. 6/6. Nees, Chemist, llardy-st.

happened; flic engine bad made at least half a dozen revolul ions and the pistons were free hv the time that they came under load; each cylinder had gone through at least one complete eyelt of operations, and was therefore filled with explosive charge; the fiywhcel had acquired a. certain amount of momentum so that when one cylinder fired the flywheel could carry the efankshaft over top dead centre despite the fact that the firing had taken place a little in advance of the dead centre. Now let us consider the matter from I lie angle of ignition t iming. If 30 degrees is the correct ignition advance for 3000 p.r.m., then it follows that 3 degrees is correct for 300, and that even one degree spark advance is a degree too much when the engine is stationary. Therefore, if we start an engine with the ignition lever in the half-way advance position we are certainly firing the charge too early. On the engine in vogue five or six vears ago no harm was done by this procedure, for, by the time that the magneto got under way sufficiently to produce a sizable spark, the engine was turning fairly briskly. With modern battery ignition, however, the ease is altered, for the battery delivers a full-power spark at the lowest speed that the starting motor is capable of rotating the crankshaft. Right from the instant that you press the starter button the ignition system commences to fiiction, and, which is more, the strength of the spark is unaffected by the position of the sparktiming lever. The old magnetos would not deliver a hot spark in the retard position, and, in fact, some of them would not produce a spark at all when they were fully retarded. The modern battery set is unaffected by timing or bv aliy engine speed normally experienced in starting.

That being the case, is it not advisable to revise our engine-starting procedure? For the past year, when starting an engine from cold, I have always gone to work in the following manner: Having first retarded the ignition fully, [ have pulled up the strangler wire and then stepped on the starter switch. After the starter lias been in operation no less than three seconds, and the engine is turning over at a fairly fast rate, I have switched on and almost immediately opened the strangler. In every case the engine has fired immediately, and during the whole year I have never experienced the slightest trouble, not even a run-down battery. The two important items in this procedure are that the spark is fully retarded and that the ignition is not switched on until the starter has had time to get the engine turning over at a fairly rapid rale.

SUGGESTED ADVANTAGES If my method is examined critically, it will* I feel sure, be found correct. By retarding tlie spark to the full extent all risks of back-firing and a bent starter motor armature-shaft are avoided. There is also the assurance that the pressure rise in the cylinder will not take place until the piston is on the down stroke. As the starter is set in motion before I switch on the ignition I am assured of at least three desirable factors: I am certain, first, that the lubricating oil has commenced to circulate before the engine fires, and that the cylinder oil film lias l)oc;n carried the complete length of the cylinder bores by the pistons; in the three or four seconds that elapse before the ignition is switched on the engine will run through several revolutions, and each cylinder will, by tlio time that it is on tlie firing stroke, have inhaled a charge of gas that has been compressed, and in the process of compress lias become at least partially vaporised; by tlie time that I do switch on, tlie engine is turning round sufficiently to obviate the slightest risk of back-fire, even if the ignition does take place a few degrees before the top’dead centre. The gas, too, has by this time commenced to move sufficiently fast in tlie induction pipe to make starting certain and to assure that the engine will continue to fire regularly and not stop again almost immediately after it has started. Try tliis procedure on your own car and sec if it is not an improvement on the old “switcli-on-and-start” method.

THIS YEAR’S T.T. RACES

WILL THE DOMINIONS CAPTURE A TROPHY? ' STRONG INTERNATIONAL ELEMENT Will one or more of the trophies in this year’s T.T. races in the Isle of Man leave the Old Country for the Dominions? Not one of the trophy cups has ever reached Dominion or Colonial shores but the names of many famous overseas riders already appear in this year’s entry lists, and, judging from advance information, they will he riding machines capable of fine performance and, possibly, lifting the trophies. But indications are that both men and machines will have to reach a very high standard and encounter an international element stronger than has ever been. The representatives of al! the competing countries are men whose racing prowess is renowned. All the Dominion and Colonial riders will be mounted on British machines, a fact that emphasises tlio supremacy of the home product. Twenty-seven different makes of motor cycle will be represented this year and one will be a four-cylinder supercharged machine built by a Birmingham firm. Never before lias a fourcylinder machine been seen in the T.T. races.

Complaints have often been made that tlie International T.T. Races are not really international, hut owing to the special inducements offered by .tlie Auto-Cycle Union (the governing body of the races) and the Government of the Isle of Man, this year’s races will include representatives from Great Britain, New Zealand, Australia, Canada, South Africa, the Federated Malay States, Germany, Italy, Belgium, Austria, Swell and the Channel Islands.