Petrol engine

“ Makers are turning their attention to petrol shunting engines, useful in goods yards, mines, sewerage works. Firms such as Messrs. Maudslay and Company, of Coventry; the Wolseley Tool and Motor Car Company; Messrs. Panhard and Levassor; Messrs. Kerr, Stuart, and Company have brought out locomotives of this kind which will draw loads up to sixty tons. The fact that a petrol engine is ready for work at a moment's notice, and when idle is not "eating its head off," and has no furnace or boiler to require attention, is very much in its favour where comparatively light loads have to be hauled. ”

“ There is nothing to choose between poppet and sleeve valves on the score of economy in running.
Economy and Durability.—A good modern petrol engine of reasonable size—say over 3 in. bore—will give one brake horse-power for an hour from the consumption of two-thirds of a pint of petrol. This means that an engine giving 121⁄2 horse-power on the brake would use a gallon of petrol every hour. But economy in petrol consumption is not the only desirable feature of a petrol engine. There must be economy in lubricating oil and in cost of replacements or repairs. ”

“ The principal method of producing petrol is by distillation of crude petroleum. The best mixture to use in a petrol engine is one composed of 2 cubic feet of petrol vapour to every 98 cubic feet of air. Petrol does not require any heat to vaporize it under ordinary atmospheric conditions. Pre-ignition of the charge is liable to occur if the compression pressure exceeds 100 lbs. ”

“ When the engine is working at its fullest power at maximum speed these apertures correspond, and consequently the largest amount of mixture passes to the combustion chamber. When, however, the work lightens and the engine begins to race, the governor comes into operation, and the holes in the plunger and plunger slide eclipse each other to a greater or lesser degree, according as a greater or lesser quantity of explosive mixture is required.
The system is more economical of petrol, and gives smoother running than governing the exhaust valves. ”

“ Whether steam will eventually get the upper hand of the petrol engine is at present uncertain. The steam car has the advantage over the gas-engine car in ease of starting, the delicate regulation of power, facility of reversing, absence of vibration, noise and smell, and freedom from complicated gears. On the other hand the petrol car has no boiler to get out of order or burst, no troublesome gauges requiring constant attention, and there is small difficulty about a supply of fuel. Petrol sufficient to give motive power for hundreds of miles can be carried if need be ”

“ In the new engine the charge enters at the head end of the cylinder, there is a special transverse combustion chamber, and many improvements are introduced in the scavenging and flow of gases; also there is no deflector at all on the piston head. Funds have not yet been secured to enable an experimental engine to be constructed, but it is to be hoped they will be forthcoming, for the benefit of the motor-car industry generally, as the future undoubtedly lies with the two-stroke. ”

“ But we must also notice that our present-day arrangements (clever as they are) are by no means perfect, and we cannot, even under the most favourable circumstances, convert more than about one-third of the heat energy of the petrol mixture into the mechanical energy of the moving piston. Of the remaining two-thirds of the heat, part is used up in heating the cylinder walls, the piston and the valves, and the remainder goes out with the exhaust gases to the silencer, finally escaping to the outside air. ”

“ The reason why we use petrol to drive our motor-cars is because petrol (and certain other liquid fuels such as benzol, etc.) contains within itself a store of energy which can be liberated as heat when the fuel is burnt or exploded in the presence of air in the engine cylinder. ”

“ The engine drives a three-bladed propeller through a long shaft with a disconnecting clutch between, so that for starting or stopping temporarily the screw can be disconnected from the engine. The petrol, which serves as fuel for the engine, is carried in a metal tank stored away inside the forward "end" box, where it is beyond any possibility of accidental damage. Sufficient fuel for a continuous run of over ten hours is carried. The engine is started by a handle fitted on the fore side of the case, which can be worked by two men. ”

“ The problem of carburation consists in forming a mixture of the correct strength and character. Air may be carburetted by passing it over the surface of liquid petrol in a surface carburettor, or by drawing it over or among wicks saturated with liquid petrol as in the wick type of carburettor, but both these methods have been largely superseded by the use of what is now known as a jet or spray type of carburettor, in which the petrol is sprayed from a fine jet and mixes with air which is passing up rapidly round the outside of the jet. ”

“ It was also found necessary to fit a hot water-jacket round a portion of the induction pipe, as the demand for petrol vapour was so great and the rate of evaporation so high that frost readily formed on the induction pipe unless the weather was very warm. The two-stroke engine requires its petrol much faster than the four-stroke, so that the float of the carburettor should be delicately balanced and the height of the petrol in the jet should be quite level with the top of the orifice, although this often leads to flooding. ”

“ As the oil is used up a fresh supply must be admitted by some form of continuous drip-feed arrangement, the oil being forced over very often from a small tank on the footboard by means of air pressure or the pressure of the exhaust gases from the engine. It is very difficult under these circumstances to estimate how much oil is present in the crankchamber at any given instant, so that there was usually alternately too much or too little. ”

“ Many readers of the 'Badminton Library' will desire to know of cars which can be used where petrol is unobtainable. Messrs. Roots and Venables in England, Koch and others on the Continent, have for a long time studied the problem of the paraffin internal combustion engine. The advantages of motor-cars fitted with these engines for use in hot climates and places where petrol cannot be purchased are obvious. Ordinary lamp-paraffin can be found in almost any part of the globe. ”

“ At the present day, even with our most up-to-date contrivances, we cannot make use of two-thirds of the available heat in our petrol. Instead of being able to turn this heat into useful mechanical work, we are compelled to throw it away—to waste it. ”

“ With the haste of a madman I returned to the coach-house I had just quitted. My hopes fell to zero. There was an unmistakable scent of petrol about the car. They rose again, however, upon a closer examination, for I saw at once that the motor was a turbine, though petrol was utilized in some way as a means of securing the necessary heat to secure the expansion of the gas for the starting of the engine, though I could see that once started, the expanded hydrogen was, as in the new car, ingeniously [233] utilized to produce the necessary heat. ”

“ It has been found, however, that many petrol engines having jet carburettors will operate with the heavier oils if the jet carburettor is suitably heated by means of the exhaust gases. In some engines it is customary to start with petrol, and then when the parts have become sufficiently heated to substitute paraffin or heavy petroleum oil, putting the heavy oil through the same spraying process as the petrol and evaporating the spray by hot walls before entering the cylinder. ”

“ Petrol-propelled engines can be started off from a station within a few seconds of the receipt of an alarm, and their pumps are ready to work immediately the fire is reached; steam-propelled engines possess the same advantage, if they are kept always standing under steam, though this involves expense that is avoided with petrol engines, which cost nothing for maintenance except while they are actually working. ”

“ Where petroleum oil can be cheaply obtained, say for twopence per gallon, one of the Otto Cycle Oil Engines, for powers up to 20 indicated horse-power, can be advantageously employed.
These engines have the advantage of being a self-contained power, requiring neither chimney nor steam boiler, and may be said to be a waterless power. The objection is the necessity to rely upon oil as fuel, and the dangers attending the storage of oil. A good oil engine should not require to use more than a pint of refined petroleum per indicated horse-power working for one hour. ”

“ It will thus be seen that liquid hydrocarbons, such as common petroleum oil, may be employed in prime motors as a substitute for either coal or steam or both. It is becoming generally recognized that for large powers, notwithstanding some advantages, the ordinary vaporizers in petroleum oil-engines are difficult and troublesome to work with. In fact, for large engines the practical plan obviously is to convert oil into gas by means of a gas-producer. Oil-gas, when cooled, can be used with great economy in the engine cylinder. ”

“ There is a great deal of difference, from an economic point of view, between spirit or carburetted air engines which we have just described and motors using ordinary commercial petroleum oil. As a rule such oil is much less dangerous, having a lower flashing-point, while at the same time it is cheaper than the more artificial products such as benzoline, naphtha, etc. We shall presently give a table comparing the cost of power produced by various systems of motors, and which will explain why the petroleum engine is gradually ousting the carburetted air motor from its place. ”

“ Then too, whatever air may escape contains no fuel, and consequently efficient scavenging may be obtained without waste.
At the high pressure at which the fuel is injected into the cylinder of the Diesel engine, practically any grade of gasoline, naphtha, kerosene, crude oil, or other form of petroleum can be vaporized. The compressed air employed in the compression and injection of the fuel is also used for starting the motor, for this is not a type that is amenable to hand cranking. ”

“ This brings about the necessity for injecting the fuel in a well-atomized condition at the time that combustion is desired and the quantities of fuel injected at this time control the amount of heat generated; that is, an infinitesimally small quantity of fuel will be burned just as efficiently in the Diesel engine as a full charge of fuel, whereas in the gasoline engine the mixture ratio must be kept reasonably constant and, if the supply of fuel is to be cut down for throttling purposes, the supply of air must be correspondingly reduced. ”

“ Of a truth, we to-day live in an age of Oil, for the products of petroleum are inseparable from our daily life. Refined petroleum breathes the breath of power to the internal combustion engine which claims a realm of its own on land and sea, in the air, and under ocean waters; it also gives artificial light to countless millions in all corners of the world under a variety of circumstances and dissimilar conditions, while the wheels of industry unceasingly revolve consequent upon oil lubrication. ”

“ In some cases petroleum is the best available fuel for an engine, essentially much the same as a gas motor. A carburetor, or atomizer, blows the oil into a fine mist almost as inflammable as gas. In small sizes for launches, threshing machines, or work-shops of limited area, the petroleum engine is a capital servant. In sizes of 75 horse-power and upward the Diesel engine is not only the best oil engine but the most efficient heat-motor ever invented. It involves [467] a principle as important as that of Watt’s separate condenser for the steam from his cylinder. ”

“ It will probably be found that no one of the 4-stroke cycle, or 2-stroke cycle, engines is best for all grades of oil, but rather that each is best for some one grade. The Diesel engine is in a class by itself, its cycle and method of control being somewhat different from the others.
An investigation of the comparative adaptability of gasoline and alcohol to use in internal-combustion engines, consisting of more than 2,000 tests, was made at the temporary fuel-testing plant of the Geological Survey, at Norfolk, Va., in 1907. ”

“ Further, a very decided saving of fuel may be effected by this combination of oil-gas producer with the internal-combustion engine, in place of the boiler and steam-engine, in many places where suitable oil is cheap or plentiful, or where intermittent work is required. On the other hand, more heat may be produced by the direct combustion of liquid fuel with dry steam and air than by converting the oil into gas before using it as a fuel. Oil-gas is a safe, rich, permanent gas made from petroleum oil, and burned with excellent results in the gas-engine cylinder. ”

“ Shielding was unnecessary because the diesel had no electrical ignition system. Carburetor icing was an impossibility because there was no carburetor.
Any excess lubricating oil in a diesel engine’s cylinder is consumed cleanly to produce power. By contrast, such oil in a gasoline engine’s cylinder is only partly burned. As a result carbon deposits form that eventually cause malfunctioning of the spark plugs, valves, and combustion chambers. This advantage accrued to the diesel because it utilized an excess of air, and in addition its cylinder walls were hotter. ”