HIGHROAD AND BY-ROAD

Waikato Times, Volume 94, Issue 14776, 15 October 1921, Page 15 (Supplement)

HIGHROAD AND BY-ROAD

A COLUMN FOR MOTORISTS. (By "Crank.") Water Injection. The vexed question whether the injection of water, with the mixture. in!o the cylinders of a motor engine is advantageous may be treated as decided by the report issued by the American 'Bureau of Standards ofthe result of a series of tests that they carried out on behalf of the Committee of Aeronautics of the United States. The report may be summarised ag follows:—No appreciable effect is produced upon the power, fuel economy and general operation of a Petrol engine by the injection of water into the cylinders at rates varying from ,0.03 to 0.44 per brake horse-power hour. When water is injected at a higher rate than O.ii pounds* per brake horse-power hour there is an appreciable decrease in t;;... power output, fuel economy, and smoothness of operation. It is thought, however, that In a badly-carbonised engine, or an engine of defective design, in which there are hot-spots that cause pre-ignition, the injection of water may result in an increase of power. It was observed that in an engine operating with high waterjacket temperature the injection of water, in amounts between two and eight pound per b.h.p hour, produces a softening and. slight reduction of carbon, particularly in the region of the piston and valves, but accompanied by a distinct falling-off in power. Apparently the tests made were most exhaustive, so they may be taken as indicating a true result. EJeotric Starters. When using the electric starters on a cold eng'ne it is worth while to inject a few drops* of petrol into the cylinders through the compression laps; this is only the work of a moment or two in the garage, and is a great saving to the battery. Although the modern starter is quite capable of starting its engine from cold if it is properly treated, a sensible practice adopted by some motor owners is to start, up the first.time each morning by hand, and to use the electric starter during-the rest of the day in the ordinary course of driving. Two objects are thereby secured: (1) The battery is relieved from abnormal strain caused by starting the engine from cold, when the oil is thick and stiff and the carburetter is working under unfavourable, conditions; (2) when the driver has to start by hand under these circumstances he wil be sure to find out all the adjustments which make for an easv start, so that the minimum expenditure of energy is required. The time during which the discharge from the battery takes place should be reduced as much as possible. Everything should be done to make the engine start easily, and all the little details which combine to make such a difference in this respect should receive attention. They are well known, most of them having to do with carburation, and the avoidance of aid leaks in the induction system.

The Right Inflation

There seems to be a theory rampant (says an expert) that in hot weather the air in the tyres expands so much that, in order to,avoid the dangers of over-inflation, some air should be let out and the pressure reduced to the beginning of the day's run. Tyre men are trying to teach the fallacy of his theory. Tyres should be pumped up as hard in the summer as during the winter. The reasons are simple and easily explained. Different tyre manufacturers have made exhaustive tests to determine the proper amount of inflation for tyres at all seasons of the year. They have found that during the hottest summer days, when a speed of 30 to 40 miles an hour is maintained, the pressure in the tyre is increased only 2 per cent. Tlrs is under extreme conditions, probably seldom duplicated by the motorist in the ordinary use of Ins car. This extra 2 per cent, pressure is so small that it is entirely negligible. On the other hand, if tyres are slightly deflated, anticipating an increase'in pressure, they are apt to he seriously injured. The Hexing of the t yrc —|he constant bending back 'md forth —produced internal friction, which heats up a type to the point where the fabric cracks and breaks down. A lyre in this condition invites tread separation, injury from stone t raises, and consequent blow-outs. But if the tyre is kept well inflated it will have one less enemy to fight in hot weather.