I think many are asked by this question 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 and is not dangerous for your power aggregateWe will analyze 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 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 engines internal combustion. 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, fuel from high degree Compression will be self-ignite, "minibuses" will occur - that is, the detonation detonation effect will be manifested!

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 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.

In any adjustable engine, one of the parameters, which without any doubt should be changed and usually upwards, is the degree of compression. Since improving the compression ratio increases the efficient engine power, therefore it is desirable to have a compression ratio as high as possible within certain limits. The upper limit is always determined depending on the point in which detonation occurs.

Since detonation can very quickly destroy the engine, so it will be better if we will know exactly what a compression ratio is or it will be to be able to withstand a reasonable ratio. The compression ratio is determined by the following formula (V + C) / C \u003d CRwhere V. This is a working cylinder volume, and FROMthis is the volume of combustion chamber.

You can simply determine the working volume or capacity of one cylinder. To do this, you just need to divide the working volume (litter) of the engine to the number of cylinders, for example, if the filter of the four-cylinder engine is 1100 cu. cm, the container or working volume of one cylinder will be 1100/4 \u003d 275 cubic meters. See Find the volume of the combustion chamber is somewhat more complicated. To determine the volume, we must physically measure it and for this we need to have a pipette or burette, graduated in the cube. See the volume of the combustion chamber is the full volume that remains above the piston when it is in the NWT. It includes the volume of the cavity in the head plus a volume equal to the thickness of the gasket, plus the volume between the top of the piston and the top of the cylinder block in the VMT and plus the volume of the recess in the bottom of the piston when using the pistons with concave bottoms or minus the volume of the bulge on the bottom of the piston when used Pistons with convex bottoms. After it is done, you can add a volume equal to the thickness of the gasket. If the gasket has a circular hole, then this volume is easiest possible to determine using the following formula: VCC \u003d [(P d2 * L) / 4] / 1,000where V. \u003d volume p. = 3,142, D. \u003d Diam. holes in the laying in mm, L. \u003d gasket thickness in the clamping state in mm. If a hole in the laying is non-circular, as it takes place in many cases, then we can measure the required amount by using the bureau. To do this, the fascinated gasket is glued to the glass sheet using a sealant designed for cylinder head laying, then place the glass on the horizontal surface and fill the hole in the laying of the liquid using the burette. Try to do it so that the liquid is not pulled out of the hole or covered the entire surface of the gasket, because in this case the measurements will be incorrect. The liquid should be poured as long as its level does to the edge of the gasket. If all the holes are round, you can easily calculate the volume between the upper surface of the piston and the upper part of the unit. This can be done using the above formula, but at the same time D. will be equal to dia. cylinder holes in mm, and L. The distance from the top bottom of the piston to the top of the block is again in mm. At some stages it is necessary to determine how much it is necessary to remove the metal from the end surface of the cylinder head to get the desired degree of compression. To do this, you first need to calculate the required full volume of the combustion chamber. From the resulting value, you will deduct the volume equal to the thickness of the gasket, the volume in the block above the piston when it is in the NTC and, if the piston is used with a concave bottom, the volume of the excavation. The remaining value is now a volume that should have a cavity in the head to obtain the compression degree we need. To make it more clear, consider the following example. Suppose that we need to have a compression ratio of 10/1, and the engine litter is 1000 cm3 and it has four cylinders. CR \u003d (V \u003d C) / Cwhere V. - working volume of one cylinder, and FROM - Full volume of combustion chamber. As we know that V. (working cylinder volume) \u003d 1000 cm3 / 4 \u003d 250 cm3 and know the desired degree of compression, so we transform the equation to get the full volume of the combustion chamber FROM. As a result, you will receive the following equation: C \u003d V / (CR-1). Substitute the specified values C \u003d 250 / (10 - 1) \u003d 27.7 cm3 . Thus, the total volume of the combustion chamber is 27.7 cm3. From this value, you deduct all components of the combustion chamber that are not in the head. Suppose that the piston has a concave bottom, the volume of the cavity in the bottom is 6 cm3 and that the remaining volume above the piston when it is in VMT, to the end of the head is 1.5 cm3. In addition, the volume equal to the thickness of the gasket is 3.5 cm3. The sum of all these volumes that are not included in the cavity in the head is 11 cm3. To obtain the degree of compression, 10/1, we must have the amount of cavity in the head (27.7 - 11) \u003d 16.7 cm3. To determine how many metal should be removed from the end surface of the head, place it on the horizontal surface, or rather place the head in such a way that its face surface is horizontal. After you do this, fill in the chamber with the amount of fluid equal to the required final volume. In this example, this volume is 16.7 cm3. Then measure the distance from the end surface of the head to the surface of the fluid and it will determine the amount of metal that will need to be deleted. There is one small problem when measuring the distance from the head of the head to the fluid level. As soon as the tip of the depth gauge is approaching the surface of the fluid, it is raised by the tip by capillary action. This capillary action takes place when using paraffin as a liquid volume medium, when the depth gauge tip is from 0.008 to 0.012 inches from the surface of the liquid and therefore it is necessary to make admission to this phenomenon. Due to small inaccuracies that occur during grinding and shaped processing of the combustion chamber, we recommend that you check the volume of each camera in exactly as well as others. If all volumes are not the same, then it should be removed from the chambers heads that have fewer volumes so that their volumes become the same as the camera large. The main reason for the need to balancing cameras is that it provides more smooth operation of the engine, especially on small revolutions, and allows you to slightly reduce vibrations arising from the same starting pulses. The second reason is that if we use the maximum possible degree of compression and, when checking, we find the chamber with the largest volume to determine the amount of metal removed, the degree of compression from other cameras may be higher than this limit value. As a result, detonation will arise, which can quickly lead to the destruction of the engine. When removing metal from the chambers, it is best to remove the metal in the top of the chambers or from the walls near the candle. The accuracy of the chambers balancing is about 0.2 cm3. Attempts to get smaller values \u200b\u200bcannot be implemented in practice, since with such extreme values, measurement features using the measuring instruments used are limited due to their errors. In addition, an error equal to 0.2 cm3, even for small-littered engines, is a small percentage of the full volume of the chamber in the head.

Change the degree of compression

The degree of compression in the turbo engine

The dependence of the octane number from the degree of compression

There are several important factors affecting the calculation of compression and they should be taken into account when designing. I will list the most important. Of course, this is the desired reducing, the octane number of fuel, the form of the combustion chamber, the effectiveness of the intermediate cooler, and, of course, the measures that you are able to reduce the temperature tension in the combustion chamber. The angle of ahead of the ignition (VN) can also partially compensate for the increased loads. But these are the topics for a separate conversation, and we will definitely affect them later in the following articles.

In the lower dead point (NMT) (full of the cylinder) to the volume of the superior space of the cylinder when the piston is position in the upper dead point (NTT), that is, to the volume of the combustion chamber.

The increase in the degree of compression requires the use of fuel with a higher octane number (for gasoline engine) to avoid detonation. Increased compression ratio in the general case increases its power, in addition, increases the efficiency of the engine as a heat machine, that is, it helps to reduce the fuel consumption.

The degree of compression, denoted by the Greek letter ε, is the magnitude of the dimensionless. The amount associated with it is compression - depends on the degree of compression, on the nature of the compressible gas and on the terms of compression. With the adiabatic process of compressing air, this dependence looks like this: p \u003d p 0 * ε γ, where

γ \u003d 1.4 is an indicator of adiabatic for diatomic gases (including air), P 0 - the initial pressure is usually taken equal to 1.

Due to the non-adiabaticity of compression in the internal combustion engine (heat exchange with walls, leakage of a gas part through looseness, the presence of gasoline in it) the gas compression is considered polytrophic with the polytropic indicator N \u003d 1.2.

For ε \u003d 10, compression at best should be 10 1.2 \u003d 15.8

Detonation in the engine - Isochorean self-estecting process of transition of combustion of fuel-air mixture into a detonation explosion without performing work with the transition of the combustion energy of fuel to the temperature and pressure of gases. The flame front spreads at the rate of explosion, that is, exceeds the speed of sound propagation in this medium and leads to strong shock loads on the details of the cylinder-piston and crank-connecting-connecting groups and thereby causes the reinforced wear of these parts. Heat Gas leads to roasting the bottom of the pistons and burning valves.

The concept of compression does not need to be confused with the concept compressionwhich is denoted (with a certain constructive conditional compression ratio) maximum pressurecreated in the cylinder when the piston moves from the lower dead point (NMT) to the upper dead point (NTT) (for example: compression ratio - 10: 1, compression - 15.8 atm.).

Encyclopedic YouTube.

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Gas engine based on ZMZ 405 with a degree of compression 12.5

Theory of DVS: Engine under HBO (General)

about the degree of compression

Subtitles

Engines racing cars operating on methanol have a compression ratio exceeding 15: 1 [ ]; While in the usual carburetor engine, the degree of compression for unleaded gasoline as a rule does not exceed 11.1: 1.

Currently only mazda company Serial produces gasoline engines SkyActiv-G with a 14: 1 compression ratio, which are installed on cars such as Mazda CX-5 and Mazda 6. However, it is necessary to understand that this is a geometric degree of compression, the actual is approximately 12 because the engine works on the Atkinson cycle, that is, The mixture begins to shrink after the late closing of the valves and shrinks 12 times. The effectiveness of such a power motor and torque is caused by such a concept as an expansion degree that is inverse to the geometric degree of compression.

In 1950-60, one of the trends of the engine, especially in North America, was to increase the degree of compression, which by the beginning of the 1970s on American engines often reached 11-13: 1. However, it required the appropriate gasoline with a high octane number, which in those years could only be obtained by adding a poisonous tetraethylswin. Introduction in the early 1970s environmental standards Most countries led to a rise in growth and even reduce the compression ratio on serial engines.

Do you say for memory, what is the degree of compression from the engine of your car? Suppose 9.8; Isn't there too much? Or maybe, on the contrary, is not enough?

Difficult question, because engine designers with spark ignition [We usually speak gasoline, although we know that car engines Perfectly work on gas. And also on alcohol - methyl or ethyl ... so it is better to express: with spark ignition. Or Otto (by the name of the creator of such a design of Nicolaus Otto) - unlike diesel. Although it sounds strange, but more precisely.] In every way to strive to increase the degree of compression. And the creators of the engines on the contrary - try to lower it ...

A peculiar characteristic of D.V., around which there is a lot of misunderstandings. Moreover, one of the key - much depends on the degree of compression. Although, at first glance, there is nothing easier: the ratio of the total volume of the cylinder to the volume of the combustion chamber. Or otherwise: private from dividing the volume of the surrounding space in N.M.T. on him - V.M.T. That is, the geometric degree of compression shows how many times the fuel-air mixture is compressed (air in the diesel cylinders) when the piston moves from N.M.T. K V.M.T. Geometric; And in life, naturally, it turns out not always, as in geometry ...

Forward and above

At the dawn of motorism, the compression of the engines of Otto (and in fact, the other 100 years ago did not know) they did it low - 4-5. So when working on low-octane gasoline (challenged as well) did not appear detonation [Who did not hear the detonation sounds in the cylinders? As they say, "fingers are knocking." With too high (according to the quality of fuel) degree of compression, the combustion of the fuel-air mixture after its ignition from the spark is violated. It acquires an explosive character, in the combustion chamber there are shock waves, from which the motor will not appear.]. Say, with the working volume of the cylinder in 400 "cubes", the volume of the combustion chamber is 100 milliliters. That is, the geometric degree of compression from our engine

e. = (400+100)/100 = 5.

If the volume of the combustion chamber is reduced - with other things being equal - up to 40 cm 3 (technically uncomfortable), then the compression ratio will increase to

e. = (400+40)/40 = 11.

Wonderful - and what? And the fact that thermal kpd. The engine will increase almost 1.3 times. And if the 6-cylinder 2,4-liter motor develops with a compression ratio of 5 power in 100 hp, then with a compression ratio 11 it will rise to non-small 130. And with the consistent consumption of fuel! In other words, fuel consumption per 1 hp per hour is reduced by 22.7%.

Striking result - the most simple funds. Isn't it too good to be true? No mysticism: the higher the degree of compression, the lower the temperature of the exhaust gases going on the exhaust. For e. \u003d 11 We simply warm the atmosphere less significantly than with degree 5; that's all.

Ases of heat engineering

Automotive engines are a kind of thermal vehicles that obey the laws of thermodynamics. Back in the 1st half of the XIX century. Wonderful French physicist and engineer Sadi Carno laid the foundations of the theory of thermal machines - including D.V. So, by carno, kpd. The internal combustion engine is the higher, the greater the difference between the gas temperature (working fluid) by the end of the combustion of the fuel-air mixture - and their temperature on the release. And the temperature difference depends on e. - Rather, on the degree of expansion of working gases in the cylinders.

Yes, there is a nuance: on carno, for thermal k.p.d. It is not a degree of compression, but the degree of expansion. The stronger the hot gases are expanding on the working move, the lower the temperature drops - naturally. Just in ordinary designs D.V. The degree of expansion geometrically coincides with the degree of compression; So we are accustomed to talk. Especially since detonation depends just from e. - That is from compression. The stronger the fuel and air mixture is compressed in the engine cylinders Otto [WHERE OTTO, Diesels detonation do not know. Why - a separate conversation.]The higher the pressure and temperature by the time of sparking, the more likely the occurrence of shock waves in the combustion chamber.

Explosive burning, detonation. It also limits the degree of compression, but the degree of expansion of working gases has nothing to do with it. Now, if somehow separate one degree from the other - so that with moderate compression, to achieve a strong expansion of working gases ...

Five-way cycle

Pourquoi would not be PAS; After all, the so-called 5-stroke ATKINSON / MILLER cycle is already known for half a century. It just breeds the degree of compression and the degree of expansion on different directions.

Imagine that your 1,5-liter 16-valve VAZ-2112 inlet ends not at 36 ° after N.M.T. (at the corner of turn crankshaft), and very late - by 81 °. That is, at 3 thousand turns of the piston at its progress to V.M.T. Pows out the part of the fuel-air mixture through the open valves back to the intake manifold (do not worry, it does not disappear there). In other words, the compression tact begins only somewhere at 75 ° after N.M.T., and before that there is a peculiar beat of the reverse displacement of the mixture.

The clocks are now not 4, and 5: inlet, reverse displacement, compression, work move, release. At first glance, the idiotic scheme: why drive a mixture back and forth? At first glance, the Sun draws around the Earth ... Watch out for my hands: Suppose the 20% of the fuel-air mixture already falling into the cylinder is displaced, and only 80% is compressed. And let the geometric e. equal to 13 - extremely high for OTTO. However, the real degree of compression, the compression is much lower: with a 20 percent reverse displacement of the mixture, it is equal to 10.6. Q.E.D.

The design with the real degree of compression is 10.6 (quite permissible for commodity gasoline) the degree of expansion of working gases - 13. Thermal kp. the engine is 1.0518 times higher than in its real degree of compression; Not so much, but the Motor Builders are fighting for the sake of 5 percent fuel economy. Engines passenger cars Already, they work with a 5-stroke cycle. Take the 1.5-liter Toyotovskaya "Four" 1NZ-FXE (for Prius) or Ford 2.26-liter (for Escape Hybrid). It seems to be a brilliant solution, however, the medals have a reverse side.

Geometric e. (Degree of expansion of working gases) in 1NZ-FXE - 13, the real degree of compression is about 10.5. The sadness is that due to the reverse displacement of the mixture, the 1.5-liter motor of software and power drops to about 1.2 liter; We win in thermal kp. - Price loss of real litter. So on the one hand, on the other hand.

Moreover, the engine with the late closure of the ink valves does not pull "on the bottoms" at all. Therefore, the 5-stroke cycle is suitable in "hybrid" power units, where the traction electromotor just assumes the load at the most low revolutions. And then picks up D.V.S.; Anyway, a 5-stroke cycle allows you to increase the degree of expansion of working gases and thermal kp. Engine.

But behind the opposite - on the contrary - forces to reduce the degree of compression. When the fuel-air mixture is supplied under excess pressure, real compression in the cylinders is too high - even with moderate geometric E. Have to retreat; Hence the reduction of thermal kp. and increased flow Gasoline in engines with superimposses, if not applying special curtain.

On alcohol

The greater the octane number of gasoline, the higher the allowable (under the conditions of detonation) the degree of compression, the more efficient the motor works. So after all it is not a single gasoline ... extremely high e. Allows in the role of fuel gas - oil or natural. Without boost, 13-14 is not a question, with a compressor - 10-11. Hydrogen is also characterized by resistance to detonation. And the alcohol is methyl or ethyl: stunning anti-knock quality qualities. In addition, alcohol is high heat evaporation; After evaporated, it strongly cools the fuel-air mixture (and at the same time the surface of the combustion chamber). The cold mixture is denser, and in its cylinder - by weight - it includes noticeably more; The real filling coefficient is higher. , Power. So they say: "compressor" effect of alcohol fuel.

Power, thermal kp. - All the pleasures immediately. In addition, ethyl (drinking!) Alcohol is also environmentally friendly; What else to wish? True, the consumption of alcohol fuel in liters turns out to be much higher than gasoline, since the calorific value of methanol and ethanol is low. Like vodka and "drying"; Take a liter on the liter here is meaningless. But in the energy equivalent of alcohol is noticeably more efficient than gasoline - due to the high degree of compression (expansion). So in the future - alcohol fuel, clean or in a mixture with gasoline. Say, E85: 85% ethanol and 15% gasoline. And years after 25 oil will lose its importance in the world ...

Truthfulness

In the future, but for now, increase the compression ratio of the vazovsky 16-valve from 10.5 to 11.5 - on the 92nd gasoline from the local gas station as not easy. For example, to apply gasoline injection directly in the combustion chambers - instead of intake channels. The evaporation of gasoline is not on the inlet, and in the cylinders - the same "compressor" effect. Or organize 2-spark ignition - with 2 candles on the cylinder; Something gives. And also supply exhaust valves with internal (sodium) cooling; Rolled plates provoke detonation. Clean the surface of the combustion chamber from Nagara - and polish it.

The configuration of the combustion chamber is affected - and the speed of the vortex movement of the fuel and air mixture. There are many ways to combat detonation - good and different.

And to what level it makes sense to raise e. Otto engine? Here is what: thermal kpd It grows with an increase in the degree of compression (expansion!), but not linear. That is, the growth of KPD. Slows out: if from 5 to 10 it increases 1.265 times, then from 10 to 20 - only 1.157 times. But quickly accumulate sidelies, which are better to avoid. Therefore, the compression ratio of 13-14 is a reasonable compromise to which it should strive. Just leave the final solution for engineers-designers; They know better.

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. That is, simple words, the higher the "octane level" of fuel, the less likely to self-ignition 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 ignition angle and the quality of the fuel mixture. Thus, the modern motor, calculated for 95 gasoline, will calmly work even on 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 a new engine, will cover, and it turns out that the breakdown is associated with 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.