What engine speed should be kept. What revs to drive, economy mode, low revs, high revs and how this mode of driving affects the car engine Low engine speeds, negative moments of driving at low revs

15.07.2019

Almost every driver is well aware that the resource of the engine and other components of the car directly depends on the individual driving style. For this reason, many car owners, especially beginners, often think about what speed is best to drive. Next, we will consider what engine speeds you need to keep, taking into account different road conditions during vehicle operation.

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Engine life and revs while driving

Let's begin with competent operation and constant maintenance of optimal engine speed allows you to increase engine life. In other words, there are operating modes when the motor wears out the least. As already mentioned, the service life depends on the driving style, that is, the driver himself can conditionally "regulate" given parameter. Note that this topic is the subject of discussions and disputes. More specifically, drivers are divided into three main groups:

the former include those who operate the engine at low speeds, constantly moving "pulled".
the second should include such drivers who only periodically spin up their motor to above-average speeds;
the third group are car owners who constantly support power unit in a mode above medium and high engine speeds, often driving the tachometer needle into the red zone.

Let's understand in more detail. Let's start with driving on the "bottom". This mode means that the driver does not raise the speed above 2.5 thousand rpm. on gasoline engines and holds about 1100-1200 rpm. on diesel. This style of driving has been imposed on many since the days of driving school. Instructors authoritatively state that it is necessary to drive at the lowest speeds, since in this mode biggest savings fuel, the engine is least loaded, etc.

Note that in driving courses it is advised not to turn the unit, since one of the main tasks is maximum safety. It is quite logical that low rpm in this case are inextricably linked with driving at low speeds. There is logic in this, since slow and measured movement allows you to quickly learn how to drive without jerks when shifting gears on cars with manual transmission, teaches a novice driver to move in a calm and smooth mode, provides more confident control over the car, etc.

Obviously, after receiving driving license this driving style is further actively practiced on own car turning into a habit. Drivers of this type they begin to get nervous when the sound of a hyped motor begins to be heard in the cabin. It seems to them that the increase in noise means a significant increase in the load on the internal combustion engine.

As for the engine itself and its resource, too “sparing” operation does not add to its service life. Moreover, everything happens exactly the opposite. Imagine a situation when a car is moving at a speed of 60 km / h in 4th gear on even asphalt, the speed is, say, about 2 thousand. In this mode, the engine is almost inaudible even at budget cars fuel consumption is minimal. At the same time, there are two main disadvantages in such a ride:

it is almost completely impossible to accelerate sharply without switching to downshift, especially on "".
after changes in the road surface, for example, on slopes, the driver does not downshift. Instead of shifting, he simply presses harder on the gas pedal.

In the first case, the motor is often outside the “shelf”, which does not allow you to quickly disperse the car if necessary. As a result, this driving style affects general security movement. The second point directly affects the engine. First of all, driving at low revs under load with a strongly depressed gas pedal leads to detonation of the motor. The specified detonation literally breaks the power unit from the inside.

In terms of consumption, the savings are almost completely absent, since a stronger pressure on the gas pedal on overdrive under load causes enrichment fuel-air mixture. As a result, fuel consumption increases.

Also, “pull-in” driving increases engine wear even in the absence of detonation. The fact is that at low speeds, the loaded rubbing parts of the motor are not sufficiently lubricated. The reason is the dependence of the performance of the oil pump and the pressure it creates. engine oil in from all the same engine speeds. In other words, plain bearings are designed to operate under hydrodynamic lubrication conditions. This mode involves the supply of oil under pressure into the gaps between the liners and the shaft. This creates the desired oil film, which prevents wear of the mating elements. The effectiveness of hydrodynamic lubrication is directly related to engine speed, that is, the higher the speed, the higher the oil pressure. It turns out that with a heavy load on the engine, taking into account the low speed, there is a high risk of severe wear and breakage of the liners.

Another argument against driving at low speeds is a reinforced engine. In simple words, with a set of revolutions, the load on the internal combustion engine increases and the temperature in the cylinders rises significantly. As a result, part of the soot simply burns out, which does not happen when permanent operation on the "bottom".

High engine speed

Well, you say, the answer is obvious. The engine needs to be revved more strongly, as the car will respond confidently to the gas pedal, it will be easy to overtake, the engine will be cleaned, fuel consumption will not increase so much, etc. This is true, but only in part. The fact is that constant driving at high speeds also has its drawbacks.

High turnovers can be considered those that exceed the approximate figure of about 70% of the total number available for gasoline engine. With the situation is slightly different, since units of this type are initially less revving, but have a higher torque. It turns out that high revolutions for engines of this type can be considered those that are behind the “shelf” of diesel torque.

Now about the engine resource with this driving style. Strong spinning of the engine means that the load on all its parts and the lubrication system increases significantly. The temperature indicator also increases, additionally loading. As a result, engine wear increases and the risk of engine overheating increases.

It should also be borne in mind that at high speed modes, the requirements for the quality of engine oil increase. The lubricant must provide reliable protection, that is, meet the declared characteristics for viscosity, oil film stability, etc.

Ignoring this statement leads to the fact that the channels of the lubrication system when constant driving at high RPMs, they can clog up. This happens especially often when using cheap semi-synthetics or mineral oil. The fact is that many drivers change the oil not earlier, but strictly according to the regulations or even later than this period. As a result, the liners are destroyed, disrupting the operation of the crankshaft and other loaded elements.

What speed is considered optimal for the motor

To save engine life, it is best to drive at such speeds, which can conditionally be considered average and slightly above average. For example, if the “green” zone on the tachometer suggests 6 thousand rpm, then it is most rational to keep from 2.5 to 4.5 thousand rpm.

In the case of atmospheric internal combustion engines, designers try to fit the torque shelf in this range. Modern turbocharged units provide confident traction at lower engine speeds (the torque shelf is wider), but it is still better to spin the engine a little.

Experts say that the optimal operating modes for most motors are from 30 to 70% of the maximum speed when driving. Under such conditions, minimal damage is caused to the power unit.

Finally, we add that it is periodically desirable to spin up a well-heated and serviceable motor with quality oil by 80-90% when driving on flat road. In this mode, it will be enough to drive 10-15 km. Note that this action do not need to be repeated often.

Experienced motorists recommend spinning the engine almost to the maximum once every 4-5 thousand kilometers traveled. This is necessary for different reasons, for example, so that the cylinder walls wear out more evenly, since with constant driving only at medium speeds, a so-called step can form.

Low engine speeds, negative driving moments at low speeds

There are two types of motors internal combustion:

Slow-moving (for example, Moskvich 2141).
High-speed (from classics to Grants or Priors).

The first version of the engine is low-speed. It is not designed to spin the motor to achieve high speed, but on traction. Slow-speed internal combustion engines are similar to diesel types. Maximum torque (for petrol type) is achieved at low speeds (about 2500 rpm).

For high-speed powertrains, peak torque is achieved in the range of 3500-4500 rpm. Thus, vehicle pulls better at high rpm.

When a high-speed type of motor is running at low speeds, the following happens:

Oil starvation. At low rpm oil pump supplies oil at a low level when the bearings (crankshaft liners) are under heavy load. As a result low pressure oils, the rubbing elements of the motor are poorly lubricated, as a result of which they begin to rub against each other, which leads to overheating and jamming of the key mechanisms of the engine.
Soot is formed in the combustion chamber. Fuel does not burn completely, nozzles and candles become clogged.
The camshaft is under load. The piston pins begin to rattle.
Detonation occurs, that is, the fuel explodes earlier than necessary (self-ignition), there is an increase in the load on piston group. The motor overheats and twitches.
There is an increase in the load on the transmission. The gearbox is poorly lubricated and forced to work under load, as a result of the “pull” ride.
Weak handling on the road. When dangerous situation, unrealistically quickly accelerated.
Fuel consumption increases. To accelerate at low speeds, it is necessary to press the gas pedal much harder than when the engine would be spinning, therefore, the mixture is additionally enriched and high flow fuel.

High engine speeds, negative moments when driving above 4500 rpm

Many drivers, having learned about the disadvantages of driving at low revs, are of the opinion that it is necessary to drive only at high revs, that is, with an engine speed of more than 4500 rpm. This mode of operation of the power unit also has several disadvantages:

With constant movement at high speeds, the lubrication systems of the engine elements and its cooling are forced to work without reserve, as a result of which even a faulty thermostat or a radiator clogged from the outside can cause the engine temperature to go off scale.
When driving at high speeds, the lubrication channels clog rather quickly, which, together with the use poor quality oil(and quality lubricant few people use), leads to “sticking” of the liners, which in the future can lead to camshaft failure.

At what speed to drive, or optimal engine speed

Experts in automotive industry agree that optimal mode for the operation of any "engine" - the speed mode is 0.35-0.75 from maximum number revolutions for this motor- it is when driving in this mode that the motor will produce the most best performance wear resistance. If the car has just been purchased, that is, it is being run-in, you do not need to accelerate the engine by more than 0.65 from the maximum speed of the power unit.

Ride performance at medium speeds (2800-4500 rpm)

The main factors of movement at medium speeds:

The fuel burns completely, no carbon deposits form in the cylinders.
The accelerator pedal is pressed less, therefore, fuel consumption is also less.
You can easily pick up speed.
The motor is running without load.

In order for the motor to be in “shape”, spinning it up to maximum speed is sometimes useful for self-cleaning of carbon deposits in the cylinders.

Pro tips on what to look for when riding and what it means to hear the engine

Riding at medium speeds is the most acceptable. In general, you need to hear the engine and feel the traction. If the gas pedal is released and you are going down the hill, then 1500-2000 rpm is not harmful, since the engine does not work “pull”.

Roar under the hood - is it scary?
On the tachometer, the red zone starts at X rpm. What revolutions can be counted (of course we are talking about intervals):
normal

optimal (in terms of consumption, resource, etc.)

acceptable (one-time, at short intervals, at large)

marginal

unacceptable

Without going into too much detail, there are 2 main sources of RPM-related engine damage:
Problems related to the strength limits of parts;

Dependence of oil pressure on the number of revolutions.

As for strength, for correct assembled engine it can withstand the maximum speed prescribed by the manufacturer without harm (the red zone of the tachometer) + another 10% - easily. The danger of "twisting" the engine, as a rule, exists on an unloaded engine (well, for example, if the gas pedal is "sunk" in neutral). When driving with the gear engaged, when "twisting" there are "special effects", such as: separation of valves from the camshaft cams, "weighted" state piston rings, violations in the chopper - mainly related to the inertia of non-rotationally moving parts. In addition, when "twisting" the engine power drops sharply. All this taken together sharply reduces the intensity of acceleration and makes it clear that there is simply no point in “turning” higher, and it will encourage you to shift gears up. In this case, the engine will not receive any significant damage.
In general, it would be more correct to talk about engine hours, and even more correct - about engine hours multiplied by the average load (as regards the effect of the number of revolutions on the durability and mechanical strength of parts).
Now for the oil pressure. Here the source of "harm" is the low engine speed, or rather the speed at which the oil pump pressure reducing valve is still closed (this valve opens when the calculated oil pressure is reached - about 3.5 kg) Of course, the oil pressure depends, in addition to the speed, also on the viscosity oil, its temperature, etc., we will omit these parameters for now. The first main point is that when the calculated oil pressure is reached, the "harm" to the engine from the number of revolutions is minimal. The second point - the maximum damage to the engine is applied to idling as well as when starting and stopping it.
Automakers have to put up with this, as the complete solution to this problem is autonomous electric drive when the oil pressure reaches the calculated value before the engine is started. However, this is very expensive.
A partial solution is to increase the capacity of the oil pump (usually by increasing the height of the gears).
However, I digress.
The oil pressure depends, in addition to the number of revolutions, also on the total cross-sectional area through which the oil flows out (in the main and connecting rod bearings, mostly). These sections increase with time, and the "harmless number of revolutions" shifts "up".
Main conclusions:
"Twisting" is not harmful, "twisting" is not worth it.

It's always better to drive at a slightly higher RPM than is accepted by most drivers.

If the red oil pressure lamp does not go out immediately when starting the engine, change the oil filter.

Hello dear motorists and blog readers. Today the topic of “driving style” will be touched upon. I hope it helps to keep long kilometers to her capital. Every time, drivers ask the question: at what speed is it better to drive a car, high or low?

And so, internal combustion engines are divided into 2 types:

1.Slow-moving(for example, Moskvich 2141)

2.high speed(from - to priors and grants)

The first type of engine is low-speed, designed for traction, and not for spinning the engine to achieve top speed. He looks like diesel type. Maximum torque is reached at low rpm (for ) (approx. 2500 rpm)

In high-speed power units, the peak torque falls in the range 3500-4500 rpm. Therefore, the car pulls better at high speeds.

What does driving at low speeds lead to?

Why all these numbers. The fact is that a high-speed type of engine, when operating at low speeds, experiences:

1.Oil starvation. The oil pump does not supply oil well at low speeds, and at this time the bearings (liners) work under heavy load. crankshaft). Due to the low oil pressure, it poorly lubricates the friction parts of the engine and over time, “metal on metal” begins to rub, which can lead to overheating and jamming of the main mechanisms of the power unit.

2.Carbon deposits form in the combustion chamber. Gasoline does not burn completely, candles, nozzles become clogged.

3.Camshaft under load. Piston fingers begin to knock.

4. Detonation occurs, i.e. gasoline explodes before it should (self-ignition), huge pressure for the piston group. The engine twitches, it heats up more.

. The box is poorly lubricated and works under load due to tight driving.

6. . At low revs, in order to accelerate, the “gas” pedal is pressed more than if the engine was spinning, therefore, the additional enrichment of the mixture - hence the greater consumption.

7.Low throttle on the road. In the event of a dangerous situation, it is impossible to quickly accelerate.

I must have scared you, now I get the impression that you only need to ride high revolutions. No, on high, also the load on all components of the car ( , ). The most acceptable ride medium speed. In general, you need to listen to the engine, feel the traction. If you go down the hill (“gas” is released), then the speed 1500-2000 rpm not harmful, because the power unit does not work “retracted”.

The main factors of driving at medium speeds (middle speeds in the range (2800-4500rpm))

The engine runs without loads;
Can pick up speed easily
The accelerator pedal is pressed less, therefore, and less consumption fuel;
The fuel burns completely, no carbon deposits are formed in the cylinders;

In order to keep the engine in “shape”, it is sometimes useful to spin it up to maximum speed, so that he self-cleansed from carbon deposits in the cylinders, so to speak, “sneezed”.

Many people say: "here Idling the engine is normally lubricated, which means you can ride them or a little higher than XX.

Do not forget that at XX the engine is running without loads. In many books for car operation it is written that it is undesirable to run the engine, more 15-20 min on XX.

Ride carefully, without forcing the engine, and then it will serve you for many years.

That's all, until we meet again.

CAR CLUB

/ "TEAPOT" ON A NOTE

TO SPIN OR NOT TO SPIN?

ENGINE RESOURCE DEPENDS NOT ONLY ON THE MARK OF THE CAR, BUT ALSO ON DRIVING METHODS

TEXT / ANATOLY SUKHOV

WITH "WEDGE"

Instructors who teach to drive "pull-in" at minimum speed have not been translated into driving schools - they say, this way the engine will wear out less. Some of them even bend the pedal or put a wooden stop under it - then, with all your desire, you will not fully open the gas. And then another driver drives - with a "wedge", frightened, as soon as the tachometer needle crosses the 2000 mark. This style is justified by fuel economy, caring for the engine.

As for fuel economy, this is only partly true. At low revs, the engine does not pull, so when overtaking or on a more or less noticeable rise, an adherent of this driving style is forced to “tread” the gas pedal, further enriching the mixture and burning the saved fuel.

So, maybe we win in the resource? At first glance, the answer is obvious: less engine speed - lower relative speeds movement of parts, respectively, and wear is reduced. But not everything is so simple. The most critical plain bearings ( camshaft, main and connecting rod journals of the crankshaft) are designed to operate in the hydrodynamic lubrication mode. Pressurized oil is supplied into the gap between the shaft and the bushing and perceives the resulting loads, preventing direct contact parts - they simply "float" on the so-called oil wedge. The friction coefficient for hydrodynamic lubrication is extremely small - only 0.002–0.01 (for lubricated surfaces with boundary friction it is ten times higher), therefore, in this mode, the liners withstand hundreds of thousands of kilometers. But the oil pressure depends on the engine speed: the oil pump is driven by the crankshaft. If the load on the engine is high and the speed is low, the oil wedge can be pressed through to the metal, and the liner will begin to break, and wear progresses rapidly as the gaps grow: it is more and more difficult to create a “wedge”, there is not enough oil supply.

In addition, when driving at low speeds, there are shock loads in the engine and transmission. The inertia of the rotating parts is no longer sufficient to smooth out the resulting vibrations. The same thing happens when touching. Recall a driving school: as soon as you release the clutch sharply at low gas, the car starts to jump. Sometimes this ends with a breakdown of the clutch: the elastic plates of the driven disk fastening to the casing do not withstand, burst, springs pop out of the windows. It is better to lose a little on wear and tear, but to avoid premature failure.

So, the more we demand from the motor ( sharp acceleration, lifting, laden vehicle), the higher the rpm should be. And vice versa, when quiet ride when the engine is lightly loaded, it makes no sense to drive the tachometer needle to the end of the scale.

GOLDEN MEAN

Accelerated wear of liners is not the only evil from the passion for low speeds. During short trips in such modes, low-temperature deposits accumulate in the engine, primarily in the lubrication system. It’s worth “driving” along the highway - and hot oil under pressure will thoroughly flush the system, at the same time, excess carbon deposits in the combustion chambers and piston grooves will burn out. Sometimes it is possible to restore the compression in the cylinders that has decreased due to the occurrence of rings.

When disassembling the "Zhiguli" motor, many paid attention to the worn recesses on the end of the valves - traces of levers. These marks mean that the valves did not rotate, but worked all the time in one position. Meanwhile, the rotation of the valve prolongs its service life, only this is possible at speeds above 4000–4500 rpm. Few bring the motor to these modes, so a notch appears on the valves. And then she herself will prevent their rotation.

But long work near the red zone is also not good for the engine. Cooling and lubrication systems are working to the limit, without a margin. The slightest defect of the first - a radiator clogged with fluff in front or sealant from the inside, a faulty thermostat - and the arrow of the temperature gauge will be in the red zone. bad oil or clogged oil passages can cause scuffing of parts or even “sticking” of liners or pistons, breakage of the camshaft. Therefore, "racers" should not lose sight of the pressure gauge and temperature gauge. Serviceable engine, refueled good oil, without problems transfers maximum speed. Of course, in this mode, its resource is reduced, but by no means catastrophically - if only the spare parts were not "left"!

Between these two extremes lies golden mean. Depending on the specific conditions, the optimal mode is 1/3–3/4 turns maximum power. In the break-in mode, too low revolutions are also unacceptable, and the upper limit should be lowered to 2/3 of the “maximum speed”. But main principle remains unshakable - the higher the load, the higher the speed should be.

COLD START

Starting in the cold is not good for the engine. Gasoline condensed on the cold walls of the cylinder does not burn out, but dilutes and washes away the oil film from them. That's why high speed an unheated engine is harmful, and on small old carbureted engines do not pull. Injection engines allow you to drive right away, but it’s better to wait a minute until the oil scatters a little through the system and goes to all nodes.

Oil starvation can occur immediately after start-up if the oil does not have time to return to the sump and the pump sips air. So if the light is on insufficient pressure oil, immediately turn off the engine for 30-40 seconds - let it drain. Cause can be like too thick oil, and his insufficient level or a clogged oil receiver (ZR, 2002, No. 4, p. 188).

HEATSTROKE

This danger lies in wait for the driver, who is always in a hurry: having won some seconds in a crazy race, he flies up to the pavement, turns off the ignition and ... at the same moment, the engine temperature begins to rise. A second ago, the thermal balance of the engine running at high speeds was maintained due to the intensive circulation of the coolant and the cooling of the radiator. But the pump pumping it over stopped, and the pistons, valves, cylinder head are still very hot. Sometimes the liquid even has time to boil, and the steam removes heat hundreds of times worse. After several such overheating, the cylinder head may be deformed, its gasket may burn out - the repair is not cheap.

There is only one way out - after an active drive, let the engine cool down at idle for at least 15–20 seconds. This is especially important on turbocharged engines. Replacing a failed turbine will cost much more than the time saved.

THE MORE WE NEED FROM THE MOTOR (SHARP ACCELERATION, LIFT, LOADED VEHICLE), THE HIGHER RPM SHOULD BE

OPTIMAL MODE - 1/3 - 3/4 TURNS OF MAXIMUM POWER

HIGH RPM FOR A WARM ENGINE IS HARMFUL

AFTER AN ACTIVE RIDE, ALLOW THE ENGINE TO COOL AT IDLING