Useful Tips

Here's how to switch the "mechanics" for better fuel economy

The age-old dispute between automotive "physicists" and "lyricists" about which transmission is better, mechanics or automatic, will continue for a long time. Automation is developing rapidly, but the vast majority of cars in our country still go to manual transmissions. Old 4-speed gearboxes are much more voracious than newer 5-speed or 6-speed ones. However, you can save on everyone.

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Fundamentals of the proper use of the capabilities of a manual gearbox

The main answer to the question of how to save gasoline on the mechanics may be the correctness and timeliness of the gear shifting by the driver. This can save up to 30% fuel.

Each gear has a recommended maximum and minimum speed. The speed ranges of adjacent gears overlap each other. For example, the first - up to 20 km / h, and the second - 15-20 km / h. Using this, you can increase and decrease the speed smoothly, without sharp jerks.

A lower gear is more powerful but slower. At the same time, low fuel costs are significantly greater than high ones. Therefore, high - more economical. Based on this, starting off and slightly accelerated, you need to switch to second gear. It makes it possible to accelerate to 45-50 km / h and go even higher. In the fork of the recommended speeds of each particular gear, you should not use the upper and lower values ​​- this will adversely affect the engine and the cost of gasoline.

It is important to timely switch to the desired gear in accordance with the speed of the car. In more modern cars, it is convenient to use a tachometer for this, which determines the frequency of revolutions of the crankshaft. The optimum crankshaft speed on diesels is 1500-2000 rpm, on gas engines - 2000-2500 rpm. Therefore, it is necessary to increase when the number of revolutions reaches:

  • for diesel engines - 2000-2500 rpm,
  • for gasoline - 2500-3000 rpm.

There is no logic in delaying gear shifting, as newcomers often sin, this will burn additional fuel. The main rule - at higher engine speeds than necessary to maintain a constant speed, you should switch to a higher gear. When slowing down, everything happens in the reverse order.

The gear up indicator, which is installed on some machines, helps to help in the correct gear changes. It analyzes the data of the transmission, engine and accelerator pedal and tells you exactly when to raise or lower.

Studies have shown that in city driving mode, the indicator helps to save 9% of fuel.

Economy Driving Style

Each press of the gas and brake pedals directly affects the fuel consumption. Therefore, smooth uniform movement is the most acceptable point of view of energy savings. Here are some expert driver tips to watch out for:

  • Don't get too close to the cars ahead. Keeping a distance eliminates the need to adapt to someone else's driving style, sharply slow down and accelerate.
  • In urban mode, you need to adjust the speed in accordance with the rhythm of turning on / off traffic lights in order to stop in front of them smoothly or to ride by inertia in green light. The clutch mechanism wears out most when braking in first gear.
  • Starting and releasing the clutch, it is better to press the gas lightly, only maintaining the desired engine speed, this will reduce the load on it.

Fuel economy at low speeds: what science says

We do not claim that the reasoning described below is the ultimate truth. This is just one more out of many.

Many drivers probably know the concept of reducing fuel consumption in a car with a manual transmission. However, as it turns out, the meaning of fuel economy is not always directly related to an earlier shift to overdrive

Even if you are a novice driver, you probably already managed to understand the basics of the concept of driving a car with a manual gear shift system for the most efficient economy: keep the speed as low as possible - and you will be happy. The more revolutions the engine spins, the more fuel it consumes. The lower the speed (within reason), the lower the consumption of this fuel. Just right?

In fact this is not true. How it is desirable to act (and why exactly) when changing gears, engineer Jason Fenske will tell in his video blog on the YouTube channel Engineering Explained.

So, if your goal is economical, unhurried driving with a manual gearbox, in general, you should keep low speed in all gears, including the highest one. But why is this happening? And will this scenario be effective in all cases and traffic situations?

As Jason explains, any moving car faces a lot of natural or mechanical counteractions that the engine has to fight against, spending the energy of the burned fuel to produce a certain amount of energy (it will be different for each type of engine) so that the car does not lose speed. Counter forces include:air resistance, rolling resistance from tires, mechanical friction forces act inside the car’s units and so on, ending with gravity.

Trying to overcome all these factors, the engine produces a certain amount of power, spending a certain amount of fuel. The amount of fuel required to overcome the opposite factors just gives the total efficiency of the car. It is called «specific fuel consumption", That is, the attitude fuel consumption (per unit of distance or time) to power or traction. Depending on how much you pressed the accelerator pedal, and depending on the engine speed, thanks to this engineering term, you will be able to determine exactly how much fuel this or that engine will consume at different loads.

From an engineering point of view, a motor at low speeds will consume less fuel due to lower friction. An engine spun up to 6.000 rpm must overcome much greater friction (from pistons rubbing against the cylinder walls, crankshaft bearings, camshafts, a water pump, and another outboard) than an engine running at 2.000 rpm.

Thus, Fenske sums up the most optimal mode for the least expensive movement - a fully open or almost completely open throttle and low, up to 2,500, revs. True, this should include a caveat: if you switch too early, in an overdrive, the engine will get into excessively low revs, which will not allow the car to accelerate and will wear out the components of the units with a pulling motion.

Much depends on the traffic situation. If the car is traveling light on an absolutely flat surface, the accelerator pedal can be pressed by 5%, while the generated power will be enough for movement and relative savings. However, as the American engineer reiterates, this mode cannot be called as effective as possible, since the throttle will be slightly open and the engine will have to spend energy to suck in air through a small gap. On the wide open throttle, the incoming air has fewer restrictions, which reduces the associated costs.

We add from ourselves that the discussion in such discussions is about saving a really small amount of fuel. Know that you will not achieve great results in savings anyway. Yes, you can save a hundred or two rubles from several tanks filled to capacity, but a miracle will not happen.

More details - in the video (turn on the subtitle translation, video in English):

P. S. I remember that the inlet gear of the phase regulator ordered me to live for a long time in my car. I was pleasantly surprised by the efficiency of the engine suddenly falling from heaven. According to subjective feelings, fuel consumption fell by 20 percent. At the same time, another problem instantly arose - the car stopped accelerating at least somehow. And this is normal. The valve opening phases went astray, less fuel began to flow into the cylinders, and power fell. Everything is interconnected in such a complex mechanical organism as a car.

Also, do not get involved in saving and constantly drive at low speeds. Switching at 2-2.5 thousand revolutions is suitable for a leisurely ride around the city, but it is contraindicated to specifically “strangle” the motor with such modes, especially when it comes to the movement of a preload or under load. At least with time, a layer of soot will appear in the cylinders that overhaul of the power unit will become the inevitable finale of an overly economical car enthusiast, maximum - there will be favorable soil for detonation, which, due to the systematic habit of driving an extra pull, will quickly damage the connecting rod and piston. Moreover, the traffic situation is unpredictable and at a dangerous moment you may need to accelerate sharply. Do you think it will be possible to do this when driving in fourth gear at revolutions of the order of 2.000 revolutions per minute? The question is rhetorical.