How to Save Gasoline
Squeezing extra miles from every gallon is patriotic. It's also common sense
WHETHER you want to save money or whether you want to save Britain, you’ll have to keep an eye on your gasoline tank.
Getting more miles out of a gallon of gasoline has therefore become a major national obsession.
Your neighbor, who a year ago didn’t know a carburetor from a front fender, will glibly explain why a series of adjustments by his garage attendant has improved his mileage.
As you drive along the highway, you see signs on all sides: “Reduce
Speed: The Tanks Need Gasoline.”
—“Save Gas: Keep the Spitfires
Flying.” On the radio you are reminded not to drive above forty.
The Government points out that cutting down on the civilian consumption of gasoline means more fuel for military needs, and military needs are of paramount importance at the present. You yourself realize that it is not only economic common sense but patriotic good taste to conserve gasoline at this time. Particularly when you see the sign on the corner gas station—“Today’s quota sold out.”
Whether it is a patriotic gesture of voluntary conservation, or a question of stretching your rationed gallons as far as they will go, makes no difference. Gasoline must be conserved !
That’s a good resolution. You and thousands of fellow Canadians are to be commended. Now take the next step of ascertaining how this end is to be achieved. Men of good will are not sufficient. You may say Tsk! Tsk!
(here insert your favorite epithet) as neighbor Smith passes you on the highway at sixty-five miles per hour.
Remembering the admonitions not to drive above forty, you think of the gas he is wasting.
But is your clutch slipping or are your brakes dragging, causing you to use twice as much gasoline as Smith? When you reach the city, do you decide you must get home in a hurry and drag out your airplane tactics? Do you zoom up to a stop light with squealing brakes, light a cigarette, and nervously glance at your enemies? At the amber, do you shove into gear and edge forward? As the green goes on, do you take off again and go braking and accelerating all the way home? If you do, your speedometer needle may never go over thirty-five, but that little display of city driving may eat up more gasoline than if you had done seventy miles an hour on the highway against a high wind.
What this sort of driving will do to your gas consumption can be estimated against the figures of a test made in Detroit. Two cars were driven ten miles in city traffic and the drivers were given no special instructions. They just drove the way everybody else did, jockeying for position, and getting away to quick starts from the stop lights. After a series of five tests, the two cars were found to average only eight and a quarter miles to the gallon. Then a second series of tests was instituted for which the drivers were given very definite instructions. They were told to maintain an approximately constant speed, avoid sharp braking
20 MPH. Con~thnt SpeedJ
30 M.Pki. (Cons~Qnt Speed)
40 M2.H, (Constord Speed)
.50 M.PH. (CQ.nltont Speed)
70 M.P.N. (Constant Speed)
80 M.P.ft jConsfont Sp~ed}
and quick acceleration and change gears as little as possible.
Over the same route, and without any change having been made in the cars, the average mileage for another series of five tests was increased to seventeen and a quarter miles per gallon. Despite this astonishing increase, the drivers lost less than jive minutes in elapsed time for the entire ten-mile circuit. A gain of over 100 per cent in economy seems ample reward for a very slight loss of time, and this test shows how much the driver has to do with gasoline consumption.
OBVIOUSLY this business of conserving gasoline cannot be accomplished merely by never driving over forty. The automobile is too complicated a mechanism to have its budget reduced to one simple rule. But there are two main divisions into which can be separated the various things that must be done. These are: (1) proper mechanical condition and (2) proper driving. If you are planning a private little campaign to get the most from your gallons of gas, the first thing to do is take your car to your garage or service station. The mechanic
will tune it up. Then all you have to do is drive properly.
What is this tune up? Once upon a time it meant an everlasting tinkering with an engine, usually by an amateur at the side of the road, with night coming on and the right tool left behind on the back porch at home. Now it means a series of systematic and accurate checks and adjustments made at certain definite periods. When a new automobile leaves the factory, the settings are accurate according to the manufacturer’s specifications; but, after a thousand miles, some parts have worn slightly, springs have taken a slightly different set, filters have picked up a lot of dirt out of the incoming air, and carbon, an inevitable by-product of combustion, has accumulated. These little things and many others must be adjusted so that their relations to each other will be such as to enable the engine to produce the best work of which it is capable.
How does the garage mechanic know how many miles you are getting for each gallon of gas consumed at any speed? He will attach a gasometer to the side of your car and cut into the fuel system at the desired speed. A reading is taken on the speedometer, the gasometer allows exactly one tenth of a gallon of gas to be consumed, and then a second reading is taken. If you have travelled 2.7 miles, you are getting twenty-seven miles to the gallon. You should be quite happy. If, however, a tune up seems to be in order, what, briefly, will the mechanic do?
First he will make sure there is no drag holding back your car and smothering the effort of the engine. If the wheels are not in line, they will scuff the tires sideways and cause unnecessary friction. If the brakes are dragging, it is just as if a big hand were holding your car from going ahead. If the clutch is slipping, part of the power of the engine is being wasted in spinning it around. If the lubricants are too heavy, or if there is friction due to lack of lubrication you are making it hard for the gears to turn around. If the tire pressures are too low, it is just the same as driving through sand or sticky mud. There is too much surface of the tire in contact with the road, creating extra friction and taking more power to turn the wheels—and more power means that more gasoline is used.
When the mechanic has made sure there is no drag, he will then proceed to check the engine. The spark plugs will be cleaned so that a spark may jump the gap between the two points and ignite the gasoline vapor in the cylinder. The distributor will be adjusted and the timing checked so that the spark will be sent to the correct spark plug at the right split second. Then the fuel system will be checked—the fuel pump which brings gasoline from the tank, and the carburetor which mixes the gasoline with air to form the gasoline vapor which is passed into the cylinder. A check will be made on the valves to see that they open the proper distance
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and in the right order. The cooling system will be examined to make sure that the engine operates at the proper temperature and finally, all the cylinder head nuts will be tightened.
The mechanic has tuned up your automobile to peak performance and economy. Now it’s up to you. Two different motorists can take this same automobile, drive exactly the same route, and yet get totally different fuel mileages. The difference lies entirely in the handling of the car.
SPEED is the first thing we might consider. It’s a great temptation to have a high-powered engine in a car and a clear stretch of highway before you. But succumbing to that temptation is a luxury that can’t be indulged in wartime. The official notices stress gasoline conservation by reducing speed, and rightly so. Alost car owners know that the faster they drive, the more gasoline they use per mile. But very few realize how much they reduce their milesper-gallon average by continued high-speed driving.
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Wind resistance alone is a tremendous factor at high speeds. At twenty miles an hour only eight tenths of one horsepower is used in overcoming wind resistance, but at eighty miles an hour forty-eight horsepower is needed. What is the horsepower rating of your engine? Unless you have a big powerful car it is probably well under one hundred horsepower. At very high speeds you are burning fuel and spending over half the energy developed bucking against the wind. Averaged for several popular makes of cars, here is the amount of horsepower used in overcoming wind resistance at various car speeds:
at 20 Al.P.H......... 0.8 H.P.
40 Al.P.H......... 6 H.P.
60 Al.P.H.........20 H.P.
80 Al.P.H.........48 H.P.
If you travel at high speeds, you are burning precious gasoline trying to fight nature. It’s bad economy.
At high speeds the pistons are moving up and down in the cylinders and sucking in vast quantities of gasoline vapor. The inlet valves are opening many times faster than usual and more gasoline jets are flowing in the carburetor. Every time the accelerator pedal is pushed down, an accelerator pump squirts an extra shot of gasoline into the carburetor to give sudden pickup. Then, somewhere around fifty-five miles per hour, an engine develops an excessive thirst and a high-speed jet in the carburetor opens up to slake this thirst. The result is that a lot of gasoline is being poured down the engine’s throat at high speeds. If the
engine is in good condition it uses all this fuel, but the power it develops is largely spent on overcoming frictional resistances. Remember that internal frictions of all sorts increase at high speeds and that at eighty miles an hour forty-eight horsepower is necessary to overcome the wind resistance. That explains these figures:
Miles Per Hour 20 30 40 50 60 70
Miles Per Gallon 25 24.7 23.3 20.9 17.2 13.0
You see the slump after sixty M.P.H. Moderate speeds pay big dividends in gasoline savings as well as in safety.
Driving in Traffic
AFTER you firmly resolve not to - do any speeding on the highway, you will find that the next big step is economical traffic driving. Erratic traffic driving is even more disastrous than high-speed operation. When you see a car zooming down the street in low gear with a black cloud coming out the exhaust pipe, you can picture a lot of dollar signs hidden in that black cloud which is made up of unburnt hydrocarbons, perfectly good fuel being wasted. A car is made to pick up speed gradually. If you want fast starts and airplane pick-ups, you can probably get them from your car but they are expensive and, in wartime, should be classed as an unnecessary luxury.
The low-gear ratios use much more gasoline than high gear and most people drive too fast in first and second and stay in these gears too long. At twenty M.P.H. low uses up gasoline 130 per cent faster than high and at thirty M.P.H. second uses up gasoline fifty per cent faster than high. It is much less spectacular and much more economical to use first merely to put the car in motion and accelerate gradually to over five miles per hour. Shift from low into second between five and ten miles per hour, and from second into high at fifteen to twenty miles per hour.
Don’t race in second and low gears but use these gears as little as possible. Sudden spurts in low and second waste fuel. When the accelerator is jammed down, more gasoline is pumped into the firing chambers than can possibly be used. It is not completely burned during the combustion period and, on the exhaust stroke, it is forced out half burnt and wasted.
Sudden braking is also expensive. You burn fuel to create energy to move the car, and then you clamp brake shoes against the revolving wheel drums and dissipate all that energy in frictional heat. Watch the traffic and the traffic lights ahead of you to avoid sudden stops. Coast in gear when you have to slow down and you will get far better mileage than the man who uses his brakes to slow down at the last moment. Sudden stops should be used only in case of emergency. Gradual stopping saves gasoline, reduces wear on tires and brake lining, and adds to the comfort and pleasure of those who are riding in the car.
Then again, did you ever realize
that thousands of gallons of gas are used by motorists every year to deliver exactly zero miles per gallon. You do that when you let your engine idle for five minutes at a crossing while a slow-moving freight goes by, when you sit in your car and talk to friends, or let the motor idle when you run into a shop. The amount of gasoline thus used is not negligible when you realize that you get no miles for your money. Turning your key in the lock and shutting off the ignition is the easiest way to save fuel.
Another way of burning gasoline with no result is to race the engine at stop signals. Many drivers pump the accelerator and hear the engine “rev up” just as if they were waiting for the green light to unleash the critter and let it go. More fuel with no miles per gallon to its credit goes shooting down the exhaust pipe. And then when you do pull away don’t slip the clutch too slowly, or part of the power will not be transferred to the rear wheels. Idling on an incline and using the clutch as a brake is wasting gas, and slipping the clutch when backing up is also wasteful. Let the clutch out definitely and regulate the speed by means of the accelerator. And, above all, don’t ride the clutch. Some people drive with their foot resting on the clutch pedal and never realize that they may be causing wasteful slippage.
Besides careful driving, there are general precautions which may help save gasoline. It has already been pointed out that tires should be kept inflated at the pressures recommended by the tire or car manufacturer. In winter, tires should be checked at least once a week. On long trips in hot weather, the heat may build up as much as five extra pounds of pressure in the tire and this will gradually force the air out of the tubes. Therefore, tires should be checked more often in the summer,
and preferably in the evening when the tires are cooler. Don’t, however, go to the other extreme and overinflate your tires. This will not increase fuel economy but it will quickly wTear out your tires.
THE SEASONS also have their influence on gasoline consumption. Soon you will have to think of the special problems of winter driving. You must expect decreased fuel economy in the winter, especially if you make numerous short runs in your car.
In winter, a car does not become thoroughly warmed up to the proper operating temperature, at which gasoline economy is possible, until it has gone about four miles. Even then the average gasoline economy is far below maximum. In extremely cold weather this can drop as low as fifty per cent. You have to drive close to eight miles before the average miles-per-gallon even approaches the normal. That is why fuel mileages drop during cold weather, especially for city driving. The longer the trip, the closer you come to averaging normal economy per mile. However, you can increase your winter mileage by taking certain j precautions.
Don’t use the choke excessively. It may be necessary for starting, but return it to normal position as soon as the engine will operate smoothly. Gasoline can also be wasted when traction is lost because the wheels slip on icy surfaces. Slow, careful acceleration on starts will reduce this winter waste. Better traction can often be secured by starting out in second or in high gear. Racing the engine to warm it up when starting is also an unnecessary gesture. Careful use of the choke will give the engine all the fuel it needs to operate satisfactorily and do it much more economically.