To understand the principles of increasing power and engine efficiency internal combustion It is necessary to know what the degree of compression, compression and octane number. Moreover, not at the level of reasoning, that the 98th gasoline is better than the 95th. It should be understood that the octane number in itself is not an end in itself, but only one of the factors of achieving the best performance characteristics DVS.

First of all, let's immediately bring clarity and we will discuss that compression and compression ratio are completely different things. The degree of compression is the relationship between the maximum volume of the cylinder ...

Or, in other words, the ratio of the total volume of the cylinder (that is, the volume of the cylinder plus the volume of the combustion chamber) to the volume of the combustion chamber alone ...

Since this is a ratio called the degree of compression, roughly speaking, there is a ratio of the volume that occupies a mixture when it is supplied to the cylinder, to the volume at which the mixture is flammable, then the pressure in which the fuel is flammable is proportional to this magnitude. That is, the greater the degree of compression, the greater the pressure of the flammable mixture.

For a better understanding, it is worth noting that since the pressure depends not only on the degree of compression, but also from, for example, pressure on the inlet phase, the pressure of the flammable mixture may be less at the engine with a greater degree of compression. How? For example, at the turbocharged engines, the compression ratio is usually less than atmospheric (why they do it - it will become clear below), while the pressure on all phases is significantly higher, since the mixture is already applied to the inlet (in which, actually, and consists their nature).

Compression is, by the way, the pressure at the end of the compression phase. That is, it is almost equal to the very pressure of the flammable mixture. Why almost? Because the mixture is always flammable a little later or a little earlier than the moment when the pressure is maximum ...

This "almost" is determined by the angle of ignition, which we, however, will not speak today. It just needs to be noted that it is also needed to combat detonation, which is lower.

Returning to the degree of compression, let's see why it is important to us in the context of the efficiency and power of the engine. But why. Work in the internal combustion engine is performed due to the expansion of the working fluid, which in gasoline engines is fuel-air mixture. As in school, they were taught: the burning mixture expands, in this case, the piston, the progressive movement of which turns into the rotational movement of the crankshaft. Accordingly, with a greater degree of compression, the stroke of the piston, in which the mixture can realize its energy potential, it turns out more, and therefore more accomplished useful work. In fact, it is only one of the factors, together they determine the thermal efficiency - an indicator of the efficiency of the working fluid expansion at the time of combustion. For him, even the formula is:

Thermal efficiency \u003d 1 - (1 / compression ratio) ^ Gamma - 1

Where gamma is the meanings of some discrete function, depending on the temperature, pressure and volume of the flammable mixture. Simply put, set of constants. So we see that the greater the degree of compression, the greater the thermal efficiency. It is also clear that this is some simplification, since to obtain its maximum value you need to pick up a lot of parameters, where the degree of compression is only one of many, although important. As the owner of one of the car services said: "No wonder the engines come up with people with two higher education." And the truth is not in vain.

Well, great, it seems to have figured out: the greater the degree of compression, the better. So let's just get rid of the combustion chamber by raising the degree of compression to heaven, and we will be happiness. And there will be no happiness, and that is why. The fact is that when the pressure and temperature increases, two unpleasant phenomena arises: detonation and premature ignition. In order to fully understand them, you need to realize one amazing fact: the fuel mixture does not explode in the engine - it burns. Moreover, the same gamma, which we mentioned above, depends on the burning rate and on the form of the flame front and on the flame temperature. The combustion rate should correspond to the speed of the piston movement. The flare front should be homogeneous and spread exactly along the progressive movement. The smaller the combustion temperature, the smaller the heat release loss. These are all simplified statements, but the general essence of the phenomena is transmitted.

Let's go back to detonation and premature ignition. Premature ignition occurs when, with an increase in pressure in the mixture, it spontaneously flammifies. It turns out that part of the work is not spent not to push the piston, but to prevent it from completing it the stroke of the compression phase, and that extension energy that will remain (if remain), will be used extremely inefficient due to an unfortunate front profile burning.

Detonation is an even more unpleasant effect when the flammable mixture explodes. That is, after a short moment when the burning applies at a speed measured by tens of centimeters per second, it suddenly increases at times. It happens under the influence and temperature and pressure, and the effect itself is ensured by the presence of a certain amount of one of the combustion products. Effects from detonation: Instead of the front of the burning, we get a shock wave (in principle, the same thing, but only many times more speed and temperature), as a result, a sharp drop in thermal efficiency and shock loads on piston group. And now, at a second, imagine what happens if detonation occurs not after the ignition of the mixture of the candle, but after self-ignition - everything is the same, but only against the stroke of the piston.

So it turns out that the degree of compression can be increased only until the effects described appear. And here we come to the next concept - an octane number. It turns out, W. different species Fuel Resistance to premature ignition and detonation varies (all instead are called detonation resistance). The octane number is just an indicator of this resistance. The higher it is higher. It is important to note that in most cases the amount of energy that can be released from liter of fuel, does not depend on the octane number.

But let's fall from theoretical moments that you can fill out several volumes, we turn to the issues practical and consider the described phenomena through the prism of everyday life.

The first common question is whether valves will ruin if fuel gasoline with a large octane number?

Indeed, in some cases, the use of gasoline with a large octane number can lead to exhaust valve extension:

It is believed that this is due to the greater the combustion temperature of the mixture with a higher octane number. In fact, the opposite is the opposite. The fuel with a large octane number is usually lit with a smaller temperature and slower. Due to the speed of combustion, it may turn out that in the release phase through the valve instead of spent gases, another burning mixture will be released. The burning mixture may also be in the graduate manifold - then he will suffer. In practice, the design of many engines allows you to realize the potential of fuel with a higher octane number without prejudice to the resource.

In any case, if you have gasoline, different from the manufacturer recommended by the manufacturer, you must clearly understand the physics of the work of your motor - what they say in the services, you can not always believe.

Question Number Two: Why when using gasoline with a large octane number on candles, a naiga is formed?

The first reason is a consequence of the fact that in Russia high-octane gasolines are obtained exclusively by adding additives. It often turns out that in order to obtain 95th gasoline, additives are used less qualitative than for the 98th. So refraining on the 95th after the 92nd, you can get a more smooth operation of the motor and the tag on the candlelight in one bottle. It is clear that everything depends on the specific gas station.

The second reason is the ignition advance angle. If there is no system in your engine that automatically adjusts the ignition angle, then the bay of high-octane fuel can again be fed up the candles and lose part of the power. As mentioned above, high-octane fuel burns slower, and consequently, for the correct and complete combustion of the mixture, its approach should be carried out earlier.

Acetone + gasoline A95 experiment №20

Description:
The most universal solvent from TM "Panacea Universal" as an anti-knock additive to gasoline. Because of the smooth more complete combustion of fuel, the efficiency increases, therefore, gasoline consumption is reduced in this case by approximately 10%. By the way, pure acetone has a similar effect.

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Let's start with Azov

A octane number is an important indicator of the quality of gasoline, which characterizes its anti-knock durability. Detonation is spontaneous, independent of the spark on the spark plug, the ignition of the working mixture in the cylinder under the influence of temperature and pressure, accompanied by an abnormally rapidly combustion. An insignificant and brief detonation, which occurs, as a rule, with a sharp increase in the load, does not pose a special threat, although it is manifested by non-hearing knocks and a characteristic "cocan", which motorists with experience are called "ringing fingers".

Large load detonation can be stronger and destructive. Thought arising from this can be "disguised" with the overall engine noise. Long detonation is extremely dangerous. It is capable of hours (or even minutes) to destroy the engine.

In pursuit of an additional power of motor-building throughout the last century, they were easiewned by the easiest way - increased the degree of compression (i.e., the ratio of the cylinder volumes when the piston is in the lower and upper dead points). More high pressure A compressed working mixture provoked detonation. Gasoline was required with an increasing octane number. If in the thirties of the last century the greatest achievement was considered gasoline with an octane number of 76, now it does not surprise 100.

The octane number of fuel is determined on a special single-cylinder engine by comparing with a mixture of isochastane (isomer of octane 2, 2, 4-trimethylpeptane) and η-heptane. The octane number of gasoline, for example, 92, means that its detonation resistance corresponds to the resistance of the mixture of 92 parts of isocutane and 8 - η-heptane. Although both substances are usually included in the gasoline, the octane number does not mean that gasoline consists of only of them. This is a much more complicated "cocktail", the exact recipe of which is often not known to know its manufacturers. When American Russell Marker from Ethyl corporation developed in 1926 the method of determining the octane number, it chose η-heptane as a zero reference for only one reason: a specific isomer hydrocarbon compound It is not possible to obtain a high purity of oil from oil, and η-heptane can be made of a pine resin.

If with an octane number in principle everything is clear, let's start to confuse everything. Octane numbers (and their at least two) are not the only units of measuring anti-knock durability. Even on the same motor bench With the help of two different techniques, two indicators are determined.

The ASTM Research Method gives us, respectively, a research octane number or, more correctly, an octane number on the research method (IOCH). Remember the beech "and" in the marking of our old gasolines?

During the test, the single-cylinder engine with a forcibly modified compression degree operates under controlled conditions with minimal load.

To determine the octane number motor method (Urban) The operating mixture is preheated in the same engine, the crankshaft turnover increases, the ignition timing is changed. Thus, gasoline is subjected to more hard and close to real exploitation test. Usually Ichocy fuel at 8-10 units is greater than its urine. This ratio is worth remembering, it can be useful for practical calculations.

In general, the standard method for the designation of the detonation resistance of gasoline in the world does not exist. In Europe and Australia use a research method. In our country, under recently we went both, as evidenced by the mentioned letter "and" (or its absence -
evidence of the use of the motor method). In New Zealand, a neighbor of Australia, the urine operates more. Even the study was carried out to reduce its minimum from 82 to 81 units. But North America is going on. There are completely different names, fortunately, denoting the same parameter. In the course there is an anti-knock-out coefficient AKI - Anti-Knock Index, Road Octane number RDON - Road Octane Number (not to be confused with Ron - Research ON - 0H in a research method), pump octane number PON - Pump Octane Number or simply (R + M) / 2. The last designation explains the essence of all previous ones. In the United States and Canada, the average arithmetic spatial numbers obtained on two different methods, that is,
AKI \u003d Icho + urine / 2. AKI for 4-5 units less than Icho
(RON). These figures can also come in handy.

Little excursion

If all of the above you understand, you have to complicate the situation. Very often, fuel sellers instead of an octane number indicate gasoline grade. At the same time B. different countries Over the same words are hiding different numbers. Moreover, uniformity is not even in separate states forming the United States.

Let's start from the native stove. We have gasoline A-92 already fed as Regular, A-95 as Premium and A-98 - like Super. It has not yet disappeared A-76, disguised under the A-80, but the fast ban left an "old man" without a name. Due to some other countries are given in a pivot table. Immediately comment on it.

The mountain states of the United States do not differ from the other mountain areas of the world. The height above sea level is more, the air is rapid. No matter how old, without pushing, the pressure in the cylinder both at the beginning of the compression tact and at its end will be lower than on the plain. Consequently, gasoline here can have reduced resistance to detonation. Remember this, going to descend from the mountains for a long time. Slightly reduced requirements for Pts in California are simply explained: it is necessary to push the inhabitants of the richest state to buy existing in the excess "hundred". Ferrari and Porsche will say Thank you. And oil traders too. In a number of countries in Europe, the 95th has long been considered "standard" or "regular." Worse do not do.

But in some countries of the Third World with Regular and Standard complications are possible: they may be similar to our A-76 (80). The information provided here is in addition to cognitive and applied value. Knowing the country of origin of the purchased foreign car, its owner will be able to determine how gasoline needs to sweep his steel horse. After all, the absolute majority of cars, except for sports, executive and tuning, are usually content with a variety of Regular / Standard without indicating the real octane manual. These figures and servicemen are useful, as helping to determine what way to eliminate, for example, the "stupidity" of the car. Just go to gasoline with a big O4 or change the expensive engine control unit. To the place, especially for mechanics, we note that strong detonation (and from strong detonation) suffer more carburetor engines. On injection usually there is a detonation sensor in the form of a miniature piezoelectric microphone, on which the signal of which electronic brains make the ignition later, reducing detonation. The engine suffers less, the owner of the car suffers more. Due to the worsened speakers and the growth of fuel costs.

Let's go back to the topic

How is all this confusion connected with the car of our colleague? His Mitsubishi arrived to us from the States. Apply to the table. And as "Japanese", and as an "American" machine must rejoice in our 92nd. And the transition to the 95th dynamics, neither economy will add it.

It is most likely that our colleague unconsciously issued the desired for valid. He should be installed on-board computer Or at least return under the stopper on the same column week-other, regularly recording the flow data and run. Then repeat the measurements on the other grade of fuel. True, considering urban traffic jams the result will still work out very approximate.

If the savings are still confirmed, there are several options for its occurrence.

The first and easiest. A certain part of the machines due to the summation of tolerances and other technological reasons has characteristics that differ from passport. And it must be taken as a given.

Second, less optimistic. Over the years of operation, Nagar and other deposits accumulated in the combustion chamber, its volume decreased, and the compression ratio, respectively, increased. What "adapted" the engine under gasoline with a higher octane number. It is treated with regular addition of anti-chain additives in gasoline plus a long ride at high speed. An alternative to the additive could be the use of the "cleaning" shell V-Power gasoline, but for the lack of unnecessary troubles will have to pay. If "chemistry" does not help, then "mechanics" remains. However, without more good reason, the engine is better not to disassemble. If "chemistry" will help, most likely, the engine will have to be adjusted.

The third is the most difficult. Buggy engine control system, ignition, exhaust recycling system. Replacing the control unit - the case is simple, but very expensive. It is worth consulted by a good diagnostic, if this is possible to find. Like a specialist in catalytic neutralizers.

Still a little theory

Numerous studies in different countries of the world confirm that the transition to gasoline with a higher octane number with a constant compression ratio does not give any advantages, but only increases the cost of fuel. The calorific value, which means, also stored energy from different grades of fuel is about the same. High octane gasoline distinguishes as much energy as standard, but is slower. As a result, did not have time to burn the fuel can be thrown into the muffler (death catalyst) and further into the atmosphere (the death of living).

Moreover, according to the site Gas Bank USA, car manufacturers (BMW, Porsche, Mercedes-Benz, etc.), even recommending high-octane gasoline, allow the use of a standard without a threat to the engine, but with some deterioration of the car parameters.

About how this deterioration can be judged by the data published by Hyundai Motor. On the PREMIUM gasoline 4.6-liter engine V8 sedan Genesis Gives the maximum power of 375 liters. p., and on standard (AKI-87) - 386, i.e. less than 2% less.

In the US SMART Fortwo operating manual, the same warning is shown as for car Mercedes.: "To ensure a long reliable operation and high engine characteristics, PREMIUM UNLEADED gasoline should be used. And at the bottom line: "Gasoline Regular will not harm your car."

We do not encourage switching to low-octane gasoline. But if your car is under it and "sharpening", does it make sense to pay extra money? With the same chemical composition equal to the energy intensity and independent of the octane number of use / non-use of additives, the only difference between the varieties of gasoline is the amount of profits received by the fuel seller.

Useful formulas

Determining which gasoline is needed by your car, it is useful to know that:
AKI \u003d RON + MON / 2;
Ron - MON ≈ 8-10;
Ron - AKI ≈ 4-5;
AKI 87USA \u003d RON 92EU;
AKI 90 ≈ RON 95;
where:
AKI - Anti-Knock Index - anti-knock coefficient (USA);
Ron - Research Octane Number - octane number on the research method (IOCH);
MON - MOTOR OIL NUMBER - octane number on the engine method (urine).

What gasoline is better pouring 92 or 95. A few words about octane number and compression ratio. Really useful material

I think many are asked by this issue on the expanses of endless Russian roads. How nevertheless gasoline is better pouring into his iron horse 92 or 95? Are there a critical difference between them, and what will happen if instead of 95 use 92 gasoline? After all, it is cheaper by about 5 - 10%, and, accordingly, from each tank there will be really savings! But is it worth it to act and is not dangerous for your power unit, we will examine on the shelves, there will be a video version and voting at the end.

At the very beginning, I suggest thinking what these numbers, 80, 92, 95, and in Soviet times 93 more? Never thought? Here everything is simple, this is an octane number. And then what is it? We read on.

Octane number of gasoline

The octane number of gasoline is an indicator characterizing the detonation fuel resistance, that is, the magnitude of the fuel ability to resist self-ignition when compressed for internal combustion engines. I.e simple wordsThe higher the "octane level" of fuel, the less likely the probability of self-ignition of fuel in compression. With this study, the fuel levels are distinguished by this indicator. Studies are carried out on a single-cylinder installation with a variable level of fuel compression (they are called WWT-65 or WEAT-85).

Installations are operating at 600 rpm, air and a mixture of 52 degrees Celsius, and the ignition advance angle is about 13 degrees. After such tests, the eyes (octane number of research) are displayed. This study should show how gasoline will behave with minimal and average loads.

With the maximum load on the fuel, there is another experiment that displays (OPC - an octane number of motor). Tests are carried out on this, single-cylinder, installation, only turns of 900 rpm, air temperature and mixture 149 degrees Celsius. Ocarm has a lower value than the eyes. In the experiment, the level of maximum loads, for example, with throttle acceleration or when moving uphill, is derived.

Now I think, at least it became clear what it is. And how it is determined.

Now let's go back to the selection - 92 or 95. Any kind be 92 or 95, and even 80. When processing it does not have this, ultimate, octane number. With a direct distillation of oil, it turns out only 42 - 58. That is, very low quality. "How so" do you ask? Can not be distilled immediately with a high indicator? It is possible, but it is very expensive. A liter of such fuel would cost several times more expensive on the market. The development of such fuel is called catalytic reforming. It is produced in this way of only 40 - 50% of the total mass and mainly in Western countries. In Russia, this method produces much less gasoline. The second production technology, which is less expensive - is called catalytic cracking or hydrocracking. Gasoline with this processing has an octane number of only 82-85. In order to bring it to the desired figure, you need to add special additives.

Additives in gasoline

1) Additives based on metal-containing compositions. For example, on Tetraethylswinse. Conditionally called eaten gasoline. Very effective, make fuel work, for the whole, as they say. But very harmful. As can be seen from the name Tetraeethylswin, there are metal - "lead". When combustion, gaseous lead compounds in the air, which is very harmful, settles in the lungs, developing complex diseases, such as "cancer". Therefore, such types are now prohibited worldwide. In the USSR, there was a brand AI - 93, he was just based on Tetraethylswinse. Conditionally, it is possible to name this fuel outdated and harmful.

2) more advanced and safe are based on ferrocene, nickel, manganese, but most often used monomethylaniline (MMNA), its octane number reaches 278 points. These additives are directly mixed with gasoline, bringing the mixture to the desired consistency. But such additives are also not perfect, they form a raid on pistons, candles, litter catalysts and all sorts of sensors. Therefore, sooner or later, such fuel is brused by the engine, in the literal sense of the word.

3) the latter and most perfect are ethers and alcohols. The most environmental and do not cause harm to the environment. But there are disadvantages of such fuel, it is a low octane number of alcohols and ether, the maximum value of 120 points. Therefore, such additives are required in fuel for quite a lot of about 10-20%. Another disadvantage is the aggressiveness of alcohol and essential additives, with a large content they faster corrosive rubber and plastic nozzles and sensors. Therefore, such additives are limited within 15% of the overall fuel level.

Degree of compression and modern car

Actually, why I began to tell from octane number and additives, but because you need to take into account fuel ignition or so-called detonation in modern units.

The fact is that manufacturers to increase power and reduce fuel consumption, slightly increase the compression ratio in the engine cylinders.

Here are some useful information:

For the degree of compression to 10.5 and below, the octane number of gasoline AI is 92 (do not take into account the turbo motor options).

From the mark of 10.5 to 12 - pour fuel not lower than Ai - 95!

Of course, there are still very rare gasoline, such as AI - 102 and AI - 109, for them the degree of compression 14 and 16, respectively.

So what happens, in theory, if we board 92 gasoline in the motor, which is designed for 95? Yes, everything is simple, the fuel from the high degree of compression will be self-propaganda, "minibuses" will occur - that is, the detonation detonation effect will appear!

And what is dangerous detonation? Yes, everything is simple, the squeezing of the gasket between the head of the block and the block itself, the destruction of the rings (both compression and oiling), the squeezing of the pistons, etc.

But this is how I wrote above - all this in theory! Especially in Russia! Why I say it. Many manufacturers understood - that high-quality gasoline (and now we are talking about 95 options), to find if it is possible - it is very difficult, even in the metropolitan regions (I am already silent about small cities). Often gasoline "Badejat" so that the octane number of 95 is unrealistic. I remember a couple of years ago, I read an article with an experiment - where in the capital they took samples from a lot of refills, and only at 20 - 25% of cases of gasoline approached the standards, the rest were far from the figure 95 and even 92. Just think! And how do you check the quality yourself? Right - in no way.

So if you pour such poor-quality fuel engine immediately? Right away? Not certainly in that way. Machines are now smart, and it is that your motor does not go "into the spread" was invented detonation sensor, it allows the motor to work with another octane number. It monitors the mechanical oscillations of the engine block, transforms them into electrical impulses and constantly sends them to the ECU.

If the impulses "go beyond the normal state", the ECU decides to adjust the angle of ignition and quality fuel mixes. In this way, modern motor, calculated for 95 gasoline will, calmly work even at 92.

But! Such work will be successful on low and medium-sized circulation, at high speed (almost maximum), the detonation sensor is not so effective, so "fry" in a low-juice mixture is undesirable!

Let's summarize.

What will happen if pour 92 instead of 95?

In fact, the difference between 92 and 95 gasoline is minimal, total "3 numbers". If you choose to refuel in the company that you guarantee exactly the "hard indicators" that is, "92 is 92", and "95 is 95" and you will be sure of it. The difference will show for your motor rather on high speeds, and not largely (up to 2 - 3%) power loss, also this percentage will grow fuel consumption.

And what is the most interesting, if you do not often spin your power unit up to 5000 - 7000 revolutions, and moving from 2000 to 4000, then 92 does not take you any negative points. Yet electronics all adjusts itself.

Prejudice - what the valve can burn, this is not. The extension of the valves was characteristic of the eaten types that metallic additives had. High-octane eaten gasolines could harm the engine configured to use AI-76 (and it has not had an electronic correction of the ignition angle and fuel injection). But now such a danger is simply no, because such fuel has long been prohibited.

But ideally! You need to fill in such a fuel that your manufacturer recommends. After all, if suddenly new Motorit will cover, and it turns out that the breakage is related to gasoline, then you fall on a very expensive repair, and at your own expense. Savings of 10% on gasoline you will "get out sideways."

What the final result I want to withdraw - to each one, if your motor is not designed for the 92nd, then it is not worth pouring it! Yet it can be fraught! However, if the cock is the modern engine, the automatic, adjusts the ignition angles and you may not even feel the fuel replacing (that is, on the 92nd you can ride, without spinning your motor up to a maximum). But if the breakdown happens, and the warranty will find out what is flooded not that fuel, the repair will be at your expense! And this, for sure, does not cost 2 - 3 rubles saving from a liter.

Now a detailed video version, look.

What gasoline is better than 92 or 95? How to refuel your car? 4.50 /5 (90.00%) 2 Voice (s)

What gasoline is better than 92 or 95? Which one to choose? This question is asked all car owners. In theory, it is necessary to pour what automakers advise. In practice, the situation is a little different. In this consider both sides.

What is 92, 95?

What do the figures mean? They denote octane number of fuel. The value describes the detonation stability of the fuel, i.e. The possibility of fuel to resist self-ignition during compression. Thus, with a high octane number, the probability of self-ignition during compression is reduced.

In the production of fuel, the octane number, the cleanest, comes around 80-85. To bring it to necessary level, stirred with different additives.

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The degree of gasoline compression.

In order to determine which gasoline is better than 92 or 95, it is necessary to understand what is compression ratioWhat it happens and what kind of engine it is.

Now, automakers will "chase" for power, with a small volume to make as powerful engine as possible. How do they achieve it? With an increase in the degree of compression, the engine power will slightly increase and fuel consumption will fall. In certainly the result, we get a powerful and economical engine. However, it is impossible to infinitely increase the degree of compression - leads to self-ignition of fuel.

The degree of compression for engines:

1. If the degree of engine compression until 10.5.It is recommended to fill the 92th gasoline.
2. If the degree of compression from 10.5 to 12It is recommended to pour 95th gasoline.
3. For above 12., It is necessary to pour the 98th gasoline.

What gasoline is better refilled 92 or 95

From a technical point of view

If you pour gasoline 92th into the engine calculated on the 95th. In which the degree of compression is higher and, accordingly, the 92nd will be ignited from the degree of engine compression. Those. Motor will detonate. Accordingly, it will be shown detonation (explosive combustion of fuel). This process, in essence, can harm the engine. After all, fuel in should be ignited from the spark plug. Those. The ignition occurs a little earlier than the piston reaches the top point, squeezing fuel. And in the 92nd it happens a bit earlier.

You can now think that your engine is designed for the 95th, and the pole 92 and nothing happens. In addition, the quality of fuel, especially in Russian realities, leaves much to be desired. After all, everyone can get into such a situation that arriving at the gas station, poured 95, and in fact, in this car, the octane number 90. In this case, in the theory, the engine should be very detonated, and almost to collapse.

Car manufacturers This fact took into account. And therefore B. modern cars Available. Located on the engine, and reads vibrations. As soon as the engine begins to vibrate not as needed. The sensor begins to transmit electrical pulses into the ECU block. If these pulses exceed some norms, the block decides to adjust the ignition advance angle and on the quality of the fuel mixture supplied. Making it enriched either poor.

The bay into the motor intended for 95, 92th gasoline, respectively, this is a detonation, detonation occurs, etc. Next, the automation, the ECU all overloads and, essentially, Do not even feel the difference.

Thus, it can be concluded that the engine is on 92 gasoline, will work no worse than 95. However, at high speeds, within 6-7 thousand rpm, the sensor will not work as correct. Therefore, "put into the floor" in low-fucked fuel we do not advise, it will destructively influence the engine.

Because The consequences may not be very good:

1. Early detonation of fuel.
2. Damage to the walls of the cylinders and pistons.
3. Accelerated engine wear.
4. Engine overheating.

Due to the fact that the fuel mixture does not burn completely, the nagar begins to accumulate on the walls of the cylinder. As a result, this leads to a decrease in the power of the motor, the drop in compression, an increase in fuel consumption. All this leads to premature wear Piston rings and damage to the walls of cylinders. Which leads soon to necessity.

But this is all the ideal, from a technical point of view. Those. Under what gasoline car is designed, such and need to pour.

What is the same reality?

Having driving at the gas station, we are confident that buying 95, acquire exactly 95, it is with this octane number? Confident in the honesty of this refueling? How can this be checked? Unfortunately, in no way.

So, what will happen if instead of 95 pour 92th gasoline? The question that torments many. So, if you prefer a quiet ride, do not press "in the floor" in your car, you can calmly pour the 92nd gasoline. It can not happen anything terrible with your engine. But under the condition of calm and moderate ride. After all it all depends on manner ride.

That is why for an active ride automakers and recommend pouring fuel with the octane number that is intended for this motor.

For turbo motors, what is the degree of engine compression. Therefore, it is recommended to fill the 95th.

However, do not forget that the value of the 92nd lower than the 95th. "Why overpay, when there is no difference?" - So think and say many car owners. There is a difference, but if you are an economical person, and sure exactly that you sell on your refueling quality gasoline 92, it is with such an octane number, then feel free to refuel.

The reality is that one time the bay of fuel with a lower octane number you cannot withdraw it immediately, but with constant savings, spend, in course the result, on expensive repair.

What will happen if instead of 92 pour 95?

If you get into the engine intended for 92, 95th gasoline, then nothing bad will not be better. Those. The engine will work softer. It must be understood that if you pour fuel with more good characteristicsThe engine is even better for the engine. Those. Detonation is excluded almost in general, respectively, fuel will be ignited from the spark plug, and not on the degree of compression.

Therefore, pouring fuel with a higher octane number, the engine will be a little better, to work slightly. Those. more octane number need more heat and compression ratio. Thus, such fuel is longer burning and highlights more heat. But you should not expect a large tide of power, or a decrease in flow, you will not feel it.

In conclusion…

Now you know What gasoline is better than 92 or 95And what better to pour. Therefore, if the engine supports fuel with an octane number 92 and above, then pour AI-92 or AI-95 is the case of everyone.

At the moment, most motors are optimized for the use of the 92nd.

Another thing, if more modern cars, and tolerances from 95 and higher. In such a situation, an attempt to save on 92 gasoline can do overhaul. And then it is worth saving?

Everyone knows that in gasoline piston engines Internal combustion The fuel-air mixture is compressed before ignition. A similar tact of diesel engines are distinguished by only the fact that air without fuel is compressed. One of of the most important characteristics Both FRO is the degree of compression. It shows how many times the volume of space over the bottom of the piston changes when it passes from the lower dead point to the top.

Sometimes this indicator is configured, despite the fact that the difference between them is huge. After all, the characteristics mentioned above are, although they are interconnected, in essence, completely different. What does their dimension indicate even. The degree of compression is the ratio, for example, 10: 1 or simply 10 and does not have units of measurement. That is, it is measured in "times". Compression shows maximum pressure Mixes in the cylinder before ignition and is measured in kg / cm2. So, compression of the DVShaving a compression ratio of 10: 1 must be no more than 15.8 kg / cm2. To say that the degree of compression can and otherwise. This is the ratio of volume above the piston located at the bottom of the dead point to the volume of the combustion chamber. The combustion chamber is called space above the piston reached the top of the dead point.

Calculation of the compression coefficient

Calculate degree compression of DVS It is possible if you can calculate according to the formula ξ \u003d (VP + VC) / VC; where Ver is the working volume of the cylinder, Vc is the volume of the combustion chamber. From the formula, it can be seen that the compression ratio can be done more by reducing the volume of the combustion chamber. Or zooming, the working volume of the cylinder, without changing the combustion chambers. VP is much more than VC. Therefore, we can assume that ξ is directly proportional to the working volume and is in the back dependency on the volume of the combustion chamber.

The working volume of the cylinder can be calculated, knowing the diameter of the cylinder - D and the piston stroke - S. The formula for its calculation looks like this: Vp \u003d (π * d2 / 4) * S.

The volume of the combustion chamber due to its complex form is usually not calculated, but are measured. Make it you can bay liquid into it. It is possible to determine the volume that mounted in the fluid chamber is possible with the help of measuring dishes or scales. For weighing it is convenient to use water, as its proportion of 1g on the CM3. It means that its weight in grams will show the volume in the cube. cm.

Effect of compression coefficient on motor characteristics

The higher the degree of compression, the greater the KVS compression and its power (with other things being equal). Increasing the compression ratio, we also contribute to the increase Efficiency engine By reducing the specific fuel consumption. The degree of compression of the engine, determines the octane number of the gasoline motor used for operation. Thus, low-fuel fuel causes a motor detonation with a large value of this coefficient. Excessively high octane fuel number will not allow power aggregatewhose compression is low, to develop full power.

Initial data

A octane number of fuel used for gasoline engines with varying degrees of compression.

The alignment of the conjugation plane of the head with a metal layer cutting unit leads to a decrease in the combustion chamber of the motor. This compression rate increases on average by 0.1 when a 0.25 mm head thickness decreases. Having at its disposal this data can be determined whether it will exceed after repairing the head of the block permissible limits. And should not take measures to reduce it. Experience shows that when the layer is removed, less than 0.3 mm consequences can not be compensated.

For what happens to change the compression ratio

The need to change this parameter of the DVS occurs quite rarely. You can list only a few reasons encouraging this.

Engine boost.

How can I change the compression rate

Increase methods:

• Cylinder boring and installation of larger pistons.
• Reducing the volume of combustion chambers. It is performed by removing the metal layer from the side of the conjugation of the head with the block. This operation is better made from the softness of aluminum on the milling or on a planer. The grinding machine should not be used, as its stone will be constantly clogged with plastic metal.

Methods of decline:

• Removing the metal layer from the bottom of the piston (this is usually done on the lathe).
• Installation between the head and the cylinder block of duraluminum spacer between two gaskets.

The relationship of the compression and compression ratio

Knowing the value of the compression coefficient, you can calculate which compression should be in the engine. However, the reverse assessment will not correspond to reality. Since compression also depends on the wear of the parts of the cylinder-piston group and the gas distribution mechanism. Low engine compression often indicates a significant wear of the motor and the need for its repair, and not a small compression ratio.

Turbocharged motors

In the cylinders of the engine having turbocharging, the air is injected with a compressor under pressure somewhat more atmospheric. So, to determine the compression indicator of such a motor, the value you get as a result of the calculation by the formula, multiply to the turbocharger coefficient. Gasoline engines The turbocharger operates on fuel with an octane number higher than that of gasoline, which consumes the same motors without turbines, precisely because their coefficient ξ is greater.