Maximum octane number. What is an octane number. Is it possible to raise the octane number of gasoline

What is an octane number and depends on it? In such a question, any motorist was asked, fueling his car with the thought of choosing a filling hose with some kind of conditional numbers above it.
Octane number - This is actually a detonation level in which gasoline flammives and explodes in the combustion chamber of your car. If the gasoline lights up earlier than you need, at the time when completely intake valves and the cylinder is not at the top point, then naturally the engine, not only may not work at full power, and it is incorrect, and that even worse, in fact we get detonation But about this below.

With such a low octane number, we will receive a bunch of problems with parts of the engine with long-term operation - valve wear, saddles for them, additional NAGA, etc. In addition, the inconsistency of the octane number for the engine entails the same additional detonation, which is often confused with the flacks of the valves.

Octane number is obtained by displacement of gasoline components. Isoocan is a substance that is almost no explosive at rising pressure, and its detonation resistance was adopted for 100 units. At the same time, the n-heptane is absolutely resistant to detonation by increasing pressure (it is possible to say a self-motive), therefore its detonation resistance is accepted for 0. It is a mixture of these substances that allows you to adjust the octane number in gasoline. In addition, gasoline added trimethylpentaneFrom which the octane number depends little. There are gasoline and with an octane number of more than 100 units, for them use isoocan With the addition of various additive volumes.

Additives to enhance the octane number of gasoline

To increase the larger octane number, aromatic hydrocarbons and paraffin hydrocarbons (alkanes) of the branched structure are added. It is using these components that an octane number increases. But how did you notice the substances used are called aromatic (aromatic hydrocarbons) i.e. Speaking by the alignment language, high-octane gasoline smells stronger than low-octane. There are also certain disadvantages in this, since high-octane gasoline is subsequently the addition of aromatic components, more volatile. With long-term storage in an open container or a certain combination of container with an external environment, it entails a decrease in the octane number of gasoline. Therefore, it can be said that high octane gasoline should be "fresh."

Earlier in the USSR to increase the octane number was used tetraethylswin - a poisonous mixture in composition with lead. Unfortunately, Tetraethylsvinets not only poisoned in itself, but also quickly displays catalytic neutralizers and Lamd-Zorda, which began to be used in the design of modern cars, as a result, it was necessary to abandon this additive. Also applied additives based on manganese, but now they are also prohibited by environmental considerations. In addition, an additive is sometimes used to increase the octane number - ferrocen . This additive (ferrocene) has an iron and creates a seriously eliminated conductive raid on the candlelight (shades of red), which worsens the operational characteristics and, accordingly, reduces the service life of the ignition candle. Gasolines include other additives and impurities. Additives in gasoline perform different tasks. Reduce the amount of harmful impurities in gasoline - sulfur, water, clean the engine parts or fuel system, increase the octane number of gasoline (it was mentioned above). Relatively harmless to the engine with an anti-idiotic additive is methyltretebutyl ether. Now it is widely used in Ukraine, Russia and Europe.

It is quite realistic to get gasoline, with an octane number of more than 110 (and these are aviation fuels). In addition, the well-known scheme with mixing gas condensate, because the octane number of natural gas is usually above 100.

The combustion of gasoline at various octane numbers.

From octane number depends the rate of combustion of gasoline, that is, actually an explosion. With high octane numbers, the combustion of gasoline occurs for a long time, smoothly .. In this case, respectively, the gases in the chamber are not allowed on the load pistons with the phenomenon of impact and excessive resonance detonation. The engine works more evenly, smoothly and clearly. Therefore, in the automotive industry and there is a tendency to produce engines of modern cars operating on high-octane gasoline.

Determination of the octane number of gasoline

It is possible to roughly define an octane number, a specialized device - octaneometry, it gives an error in octane numbers by 5-10 units. Therefore, simply speaking, check the quality of gasoline there is no possibility without a labator research.
In the labararatoria, the octane number is determined in two ways:
- Motor (MON)
- Research (RON).

In the United States, the octane number is replaced with the so-called octane index, which is the average-polymetic number of octane numbers obtained along the engine and research method for this fuel. But in Japan, only a research method is used to indicate gasoline brands. On our gas stations it is also the octane number obtained by the research method is also declared.

The use of gasoline with an inappropriate octane number for the engine.

The use of gasoline with a low octane number.
If it happened so that you were refueling the car with low-fuel, listen to the engine. If the engine works stably, but does not pull badly, there is nothing terrible in this, just burn all the low-fledged gasoline and in the future fuel gasoline with a regulatory octane number. At the same time, try to avoid dynamic driving, to avoid detonation in the engine.
But if there are angular sounds from the engine, which are often confused with the lock valves, then this means that the mixture detonates earlier than the valve closes . In fact, this explosive wave applies to the engine block and in the exhaust system. In this case, this can lead to the root of pistons and exhaust valves, the fact of negative impact will be available. »Natural" detonation can sometimes be observed in cases of excessive loading of the engine, when lifting a slide, when moving on increased gear. The long-lasting operation of the engine, even with the "natural" detonation, is invalid, as this can lead to overheating of the engine and, as a result, damage to the gasket of the cylinder head, the troughing of the pistons and valves.

Gasoline use with high octane

You do not need to try to apply high-octane gasoline for cars whose engines are not designed for it. The cons of this application is also obvious if the originally design was developed under low octane gasoline numbers and you were applied high octane gasoline, it will entail a complete reconfiguration of intake and exhaust gases Ah and possibly replacing some components of the engine. The burning time of gasoline in this case longer and in fact will need to set up a piston group and inflammation in such a way that the expansion of the volume of the cylinder is the piston equal to the burning time, while the valve would be closed. In fact, on the tuned engine, gasoline burns off late, and the power loss will also occur.

Many motorists would be interested to learn about the octane number of gasoline. Every day, they refuel their car with some definite gasoline, without even thinking, which means one or another number (92.95 or 80). In this article, we give the basic information that any self-respecting vehicle owner should know.

Octane number. What is it?

This definition characterizes the measure of chemical fuel resistance to ignition. That is the higher the octane number, the more stable fuel to spontaneous ignition. It is very important. In the process of the movement of the piston (in the extremely upper position), the fuel and air mixture may be under great pressure. If the octane number is low, then gasoline flammifies (without sparking). This phenomenon is extremely negatively affected by the engine.

Probably, every owner of the domestic car knows what detonation is. So this phenomenon occurs just because of the poor quality of gasoline. In the process of operation of the engine, unnecessary noises may appear, which are very bored by car enthusiasts. This occurs due to the collision of the high pressure waves generated during the incorrect operation of the motor.

What is dangerous detonation?

For the engine, the presence of detonation is an extremely dangerous moment. Uncontrolled ignition can lead to the melting of piston holes. In most cases, rods can even be brought. Ultimately, the motor will require major repairs. Fortunately, on modern cars, such a breakdown is excluded, because control is carried out using computer blocks. Special sensors come into operation, which track the appearance of detonations. As soon as such manifestations are detected, the special module returns control over the fuel mixture. Depending on the situation, the level of superior is reduced or the candle ignition time is drawn. That is, the computer unit independently protects the engine.

The higher the degree of compression of the pistons in the engine, the higher its power with the minimum volume of gasoline mixture. In modern machines, the compression ratio can be 10: 1, but in some cases it may be higher. Contrary to the stereotype of many motorists, the engine with superior has, on the contrary, a smaller degree of compression. Machine manufacturers must take into account the compression ratio and control this parameter. The maximum compression magnitude in sports cars, so high-octane fuel must be used there.

It is important to remember that intraconduce pressure needs high-quality fuel with a high octane number. Only in this case it will be possible to guarantee the absence of self-ignition. Of course, the error is not excluded and the tank can get at all the type of fuel.

What happens if there was gasoline with a low octane number in the tank?

Suppose, a person has a new foreign car in which he flooded instead of gasoline with a 95th or 98th octane number, fuel with class 80. The first feature will be the appearance of non-ache for the engine noise. Consequently, to the nearest refueling it is necessary to go very carefully, without casing the number of revolutions. It is quite natural that the engine will decrease in the engine, the "voraciousness" of the vehicle will increase. Significantly reduces the strength of the exhaust catalyst due to heat from it. Thus, you need to pour into the tank only the fuel recommended by the manufacturer.

Is it possible to calculate the octane number yourself?

There are two popular methods that allow the accurate calculation of the octane number - motor and research. Any of these methods should be implemented in special conditions. To begin with, the selection of high-quality mixtures of reference hydrocarbons with a number 100, as well as normal N-heptane with a number of 0. Next, the determination of the octane number is carried out on a special installation. In the engine method, the high load of the motor is impected. At the same time, the mixture is well heated to 150 degrees Celsius. During the experiment, the motor rotation frequency should be at the level of 900 revolutions per minute. With a research method, the mixture will not be heated, and the speed of rotation will be at the level of 600 revolutions per minute. It should be immediately noted that in the case of the research method, the octane number will be part of several units above (most often 7-10). There is an old GOST, according to which the measurement of the octane number 76 and 72 of gasoline is performed using a motor method. As for high-octane fuel (from 93 to 98), it is tested exclusively by the research method. There is another way to determine the octane number, which is available to each ordinary - the use of a special device. But here it does not have to count on high measurement accuracy - the error will definitely be.

The principle of operation in all devices, measuring the value of the octane number, is identical. On the market there are devices of both domestic and foreign production. The most popular and well-known instrument of this type made in the Russian Federation is octis. Its value is about 3.5 thousand rubles.

More accurate and reliable - Digatron. Its price will be 2-3 times higher - about 700 euros per piece. It is he who is most widely used to solve the tasks under consideration.

Often used in karting and other sports. The principle of its action is quite simple. Two measurements are produced - reference fuel and another, whose octane number must be measured. Further, the received data is simply compared.

At the same time, fuels of different manufacturers in all cases without exception have differences from each other. Accordingly, the calibration dependence of the dielectric constant - the octane number differs significantly. Therefore, it is required in each case to build individual calibrations. As a standard, the fuel of a particular manufacturer is necessarily applied. A octane number must be pre-measured on a special installation.

Is it possible to raise the octane number of gasoline?

Most often, various paraffin and aromatic hydrocarbons are added to it to increase the octane number of gasoline. It is very important that these elements have branched structures. The stronger the smell of gasoline, the higher its octane number. That is why in an open container to store gasoline is not recommended - this can lead to a decrease in this parameter. Another method is the use of special additives, many of which, by the way, are prohibited due to increased harm. By the way, the letter "and" in the abbreviation "AI" means that the measurement of the octane number was carried out by the research method. Alcohol-based additives One of the often previously used methods is the addition of alcohol. Moreover, it could be both ethyl and methyl. For example, if you add 1/10 part of ethyl alcohol to gasoline with octane number, then its detonation resistance increases to 95. The concomitant effect will be a significant reduction in exhaust toxicity.

But it is important to remember that an increase in octane number in such a way leads to a rapid increase in the pressure of vapors. What can cause steam plugs in the fuel line system.

In addition, alcohol is very hygroscopic. Special methods for storing such fuels must be applied, monitor the amount of water in the mixture. Her entering the engine can cause serious breakdowns, the need for expensive repair. Additive to increase the octane number of gasoline Unlike the decrease in the octane number, the increase in this indicator usually does not cause any difficulties. There are many special additives that allow manipulated by this indicator. The magnitude of this increase, as well as other parameters depend on the specific type of product. The most popular additives today: "Octane Plus" Octane Plus - an increase of 2-2.5 units; LAVR NEXT OCTANE PLUS - up to 6 units; Astrohim Octane Plus is an increase of 3-5 units. It is necessary to use gasoline only with the parameters recommended by the manufacturer. Otherwise, the likelihood of a wide variety of problems with the engine is great.

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What is an octane number of gasoline and what depends on it? In this question, almost every motorist was asked for refueling his car, with the idea of \u200b\u200bchoosing a filling hose with some conditional numbers above it.
The octane number is actually the level of detonation, in which gasoline flammives and explodes in the combustion chamber of your car.

What will happen if the octane number of filling gasoline is very different from the design

If gasoline flashes earlier than necessary, at the time when completely intake valves are not yet closed, and the cylinder is not at the top point, then it is natural that it will not be much more useful power from this explosion. She just seals the pipe! The engine will work at full power, detonation will appear, "sneezing", etc. etc. With such a low octane number of gasoline, we will get a bunch of problems. And this is not only power loss. Here and the wear of the valves and the saddles under them and the additional naughte ... In addition, the inconsistency of the octane number for the engine, entails the same additional unplanned detonation, which can be confused with the lock valves. But the case is not at all!
The same can be said about the case when an octane number is overestimated. The explosion in the combustion chamber will occur with the receipt, that is, when the valve has already managed to open. From here all the same problems, but from the mirror side, that is, not before the valve closed, and after they have already opened ...

Modern engines have automated power management systems, so-called ECU. Which constantly monitor the ratio of fuel and air in the combustion chamber, detonation, the speed of rotation, the ignition period of the mixture of candles, the time of fuel injection into the chamber. All this allows you to slightly adjust the "correctness" of the work, which means that gasoline with some scatter by octane number. That is, if gasoline 95 is declared to the car, it will certainly be not bad for 92, however, the use of 80 gasoline will clearly affect the operation of the engine. With such a wide range of adjustments to all the characteristics of the engine, the ECU will simply do not cope.

How the octane number of gasoline is laid in production

The octane number is obtained by shifting the balance of components of gasoline. By and large there are two of them. This isoocan and n-heptane, the rest is still not so substantially, at least for the octane number of gasoline. Isoocan, the substance is almost no explosive. It is small reacting to an increase in pressure and temperature, to a known limit. As a result, his detonation resistance was adopted for 100 conditional units. At the same time, n-heptan is not at all racks to detonation with a slight increase in pressure. It can be said to be self-containing, therefore its detonation resistance is accepted for 0 conditional units. It is a mixture of data of the components and allows you to adjust the octane number in gasoline, receiving gasoline with different octane numbers: 80, 92, 95.98. In fact, gasoline is and with an octane number of more than 100 units. In this case, only isophane is used, with the addition of various additive volumes. It is about additives that increase the octane number of gasoline, we will also tell me further.

Additives to enhance the octane number of gasoline

To increase the octane number, aromatic hydrocarbons and paraffin hydrocarbons (alkanes) of an extensive structure are added. It is with the use of these components and an octane number increases. But as you noticed, the substances used are called aromatic (aromatic hydrocarbons), that is, in the language of the alone, high-octane gasoline smells stronger than low-octane. There are also certain disadvantages in this, since high-octane gasoline due to the inclusion of aromatic components of more flying. With long-term storage in an open container or with a specific cubization message with an external environment, will lead to a decrease in the octane number of gasoline. Therefore, it can be said that high-octane gasoline should be "fresh". Earlier in the USSR, a tetraethylswin is used to increase the octane number - a poisonous mixture in the composition with lead. Unfortunately, Tetraethylsvinets not only poisonously in itself, but also quickly displays catalytic neutralizers and lambd probes, which began to be used in the design of modern cars. As a result, I had to abandon this additive at all. Also applied additives based on manganese, but now they are also prohibited by environmental considerations. In addition, an additive - ferrocene is sometimes used to increase the octane number. This additive (ferrocene) has an iron in its composition and creates a difficult to-conduct conductive raid on the candlelight (shade of red), which worsens the performance characteristics, (they can be viewed in the "Ignition Candles" section) and, accordingly, reduces the service life of the ignition candles. Gasolines include other additives and impurities. Additives in gasoline perform various tasks. Reduce the amount of harmful impurities in gasoline - sulfur, water. Also clean the engine parts or fuel system. Relatively harmless to the engine with an anti-idiotic additive is methyltretebutyl ether. At the moment it is most widely used in Ukraine, Russia and Europe.
It is quite realistic to get gasoline, with an octane number of more than 110 (such fuels are, but again with lead additives, which will repeat unacceptably for modern car engine control systems). In addition, the well-known scheme with mixing gasoline and gas condensate. In this case, it is also possible to "pull up" an octane number. After all, the octane number of natural gas is usually above 100 units.

Gasoline combustion with different octane numbers

From octane number depends on the rate of gasoline combustion, that is, actually the time of the explosion flow. With high octane gasoline numbers, longer and smooth combustion of gasoline occurs. At the same time, respectively, explosive gases do not cause shock loads and excessive resonant detonations on the pistons. The engine works more evenly, smoothly and clearly. Therefore, the automotive industry and there is a tendency to produce motors of modern cars operating on high-octane gasoline. In this case, with a normally tuned engine and the proper octane number of gasoline, detonation will be minimal.

Determination of the octane number of gasoline

It is possible to determine the octane number by a specialized device - an octaneometry. It gives an error in octane numbers by 5-10 units. Therefore, simply speaking, check the quality of gasoline there is no possibility without laboratory research. In the laboratory, the octane number is determined in two ways:

Motor (MON), in more detail about this method of determining the octane number, you can learn from the article "Motor Method for determining the octane number of gasoline";
- Research (RON).

After research, the following indicators are obtained in the table below

Research motor octane index trade name
method method
A-80 A-76 78 Standard
AI-91 A-82,4 86.7 Regular
AI-92 A-83 87,5 Regular
AI-95 A-85 89 Regular
AI-93 A-87 91 Premium
AI-98 A-89 93,5 SUPER

In the United States, the octane number is replaced with a so-called octane index, which is a medium-tariff component of octane numbers obtained by a motor and research method for this fuel. But in Japan, only a research method is used to indicate gasoline brands. Okthan number received under the research method is also declared on our gas stations.

The use of gasoline with inappropriate octane number for the engine

Application of gasoline with low octane number

If it happened so that you were refueling the car with low-fuel, listen to the engine. If the engine works stably, but does not pull badly, there is nothing terrible in this, they simply burn all the low-octane gasoline and subsequently fuel gasoline with a regulatory octane number. At the same time, try to avoid dynamic driving, to avoid detonation in the engine and overload.
If ringing sounds are heard from the engine, which are often confused with the flap of valves, then the mixture is detonated earlier than the valve closes. In fact, this explosive wave applies to the engine block and in the exhaust system. In this case, this can lead to the root of pistons and exhaust valves. Of course, it may not be in the case of burning one fuel tank, but the fact of negative influence will be obvious. The "natural" detonation can sometimes observe in cases of excessive loading of the engine, when lifting a slide, when moving on increased transmission. Long operation of the engine, even with a "natural" detonation, is unacceptable, as this can lead to overheating of the engine, and as a result, damage to the gasket of the cylinder head, roasting the pistons and valves.

Gasoline use with high octane

It is not necessary to try to use high-octane gasoline for cars, whose engines are not designed for it. Cons of such an application are obvious. If the originally design was developed under low-octane gasoline numbers, and you used high-octane gasoline, it will entail a complete reconfiguration of intake and exhaust gases, and possibly the replacement of some components of the engine. The time of the explosion for gasoline, in this case, will be slightly tightened, that is, not on time. In fact, it will be necessary to configure the valve and ignition. On an unconfigured engine, high-octane gasoline will be burned off with the receipt, the power loss will occur.

Today we will talk about such a rarely discussed by the manifiers, as an octane and cetane number in fuel. What is this compared one with another? What is the difference? Where is the octane, and where is Cetane? And do I need to know this?

Octane number

Let's start with the basics of the most simple and common indicator, octane number. It is used as a gasoline valuation scale. Octane numberhow many most likely heard it is an indicator that characterizes the detonation resistance of gasoline, that is, the possibility of fueling to resist spontaneous ignition when compressed .

What does this mean? Gasoline with a higher octane indicator can be compressed to higher atmospheres (high pressure), while the fuel-air mixture will not flame ahead of time. In other words, you can bring such a conclusion under one of those numbers that we are usually visible at refueling: 92, 95, 98, is an indicator of how much you can squeeze the air-fuel mixture before gasoline lights up.

C₈h₁₈ Oktana Mockup

If there is a premature fire ignition, an electric spark is asked at a given period of time, we will get the so-called detonation, the phenomenon is extremely harmful to any motor with which engineers have long learned to fight. As you can see, including the fuel.

By the way, did you know that the alkane scales that are included in the octanes are extended from 0, this indicator corresponds to heptane (C₇H₁₆) to an indicator of 100 units, which corresponds to the octane (C₈H₁₈)? Now you know or at least remembered. Here is such a slight retreat in the chemical debrist of the school program.

What else is high-octane gasoline useful, except for the absence or minimal presence of detonation? With a high compression indicator, the engine is capable of developing more torque at the same volume of the fuel consumed. That is, the engine becomes effective. At the same time, the engine allows you to put the phase in advance, which will give a time supply when the piston moves into the upper dead point and the mixture optimally.

Finally, thanks to the above pluses, high-octane fuel works better in engines with turbines and superchargers.

A few words about low-octane gasoline. All those indicators, only with a minus sign, are observed in fuel with a low octane number. This causes the use of gasolines AI-80, 92 and in relatively low-power atmospheric motors.

Cetane number

Cetane is used for similar estimate scales, only diesel fuel. The characteristic of the flammability of diesel fuel, which determines the period of delay in the combustion of the working mixture.

What does it mean?This is a measurement of the time gap, from the moment when the fuel is injected into the cylinder and when this fuel starts to burn. On science - the time interval passing from fuel injection into the cylinder before its ignition .

The high cetane number of diesel fuel will be a measured indicator of how much fuel is quickly flammable after injection into the cylinders. And, on the contrary, a low cetane number means that for the ignition of the fuel will require some time interval.

C 16 H 34 Layout Cetane

The cetane indicator is also measured on the scale of hydrocarbons, the extreme left in which 1-methylnaftaline will be (C 11 H 10) - 0, 100 - cetane (C 16 H 34) is displayed.

The advantage of accelerated diesel fuel ignition is that the engine running on it can develop more torque, the ignition delay will be minimal, the speed of the revolutions will be higher. Synchronization of the phase operation using the engine operation on highly acetan fuel can be carried out more accurately, flamming the fuel and air mixture at the moment when the maximum torque is required.

The final plus of the high grade of cetane can be called low hydrocarbon emissions into the atmosphere, since such fuel combines more. But, at the same time, the studies show, solid particles from the exhaust pipe are ejected more than in diesel fuel with a low cetane.

Be that as it may, the higher the cetane number, the better, this is an indicator of better DT.

We hope now there will be no questions.

Video taken with YouTube-channel: "Engineering Explained"

Most of the car owners are vaguely represent what an octane number is. As a rule, their knowledge is limited to understanding that the higher this indicator, the more. Alas, but such a interpretation is far from truth. And since novice drivers teach very many things, but it does not turn into the training course, the product of information on this topic does not prevent anyone.

The purpose of the octane number of gasoline and how to change it.

Under this incomprehensible term understand the degree of fuel resistance in liquid form to detonation. In other words, what is the threshold of gasoline inflammation under pressure, that is, when compressed. A mixture of two hydrocarbons is taken as a reference: isoocotan and n-heptane. However, the definition methods of PF may differ, so there is a classification of this indicator depending on the method of determining:

• Eyes - Research Pts;
• Ochm - Motor Pts.

Since the instrumental mechanisms of these methods do not coincide, there is a difference between the values \u200b\u200bof the eyes and void, which is called the sensitivity of liquid fuel. Both methods are laboratory. And if we are talking about the real indicator, obtained on the working force unit, they talk about the actual octane number. It is determined using a special bench on the engine running. But the most approximate by reality is the indicator of the PTS, which is measured on a moving vehicle.

Isoocan is a substance that refers to almost non-flammable under the action of compression force, so the mixture consisting only of it has the highest possible Och equal to 100. On the contrary, the mixture consisting only of n-heptane, has a zero octane number. At the same time, the combustion of the N-heptane as a result of the impact of even minimal pressure is accompanied by characteristic knocks in the CPG, which are called detonation. It is them that arise if the use of fuel with an octane number is unsuitable for this power unit. Metal ringing is formed as a result of the propagation of sound waves appearing as a result of too fast combustion of fuel assembly. Repeatedly reflecting the surface of pistons / cylinders, they become well heard and recognized by experienced drivers. Thus, the octane number shows how quickly it occurs in the engine cylinders.

Effect of Och on the characteristics of the power unit

The dependence between the velocity rate of gasoline and the OS has a linear view. The lower the octane number, the less time is required to ignite the fuel assembly, which directly affects the fuel consumption - if it burns faster than it is supplied, then it enters the combustion chamber with an increase in the corresponding rate. But this does not mean that, simply increasing Pts, we can save: if the combustion is slower than it is also bad, since the motor efficiency decreases, which leads to the loss of engine rigging and deterioration of dynamic characteristics. Filling into the engine running on the 95th gasoline, fuel with Och, equal to 92, you will receive. If the situation is the opposite (instead of the working 92th, we fill 95th), the flow will remain the same, and the motor power will decrease. So it is possible to use inappropriate gasoline, but undesirable. This is recommended only for force majeure circumstances, but not on a regular basis.

How to determine the octane number of gasoline

According to GOST 511/82, it is measured using a special installation WWT65M, consisting of the following components:

• the device measuring detonation;
• single-cylinder motor, characterized by a dynamic degree of compression and dedication;
• devices designed to regulate the likelihood of detonation processes.

The measurement algorithm itself is as follows:

• the engine is poured into the engine and, manipulating the degree of compression, achieve the appearance of detonation phenomena of a particular value;
• the reference mixture is characterized by the same detonation value, and according to the ratio of n-heptane, the whole source fuel is determined to isochastane.

GOST 8226/82 describes the measurement procedure by the Och Research Method. In this case, the mode of operation of the motor is characterized by smaller loads, as a result of which the eyes always turn out to be somewhat large. If there is a need to independently measure the octane number, it can be done using instruments available in free sale. As an example, an octaneometr can be brought, in which the measurement method is used, based on the diethritic permeability of liquid fuel (this value varies in proportion to the octane number).

The peculiarity of the method is to compile a calibration scale that allows you to determine Och with an acceptable accuracy. To build such a scale, some n-heptane and gasoline will be required with a precisely installed octane number. A similar procedure can also be used to determine the cetane number for diesel fuel. The possibility of using this method is based on the fact that currently gasoline is manufactured without using the direct distillation method, and through Campaudiov technology, or mixing components. However, the deficiencies of the octane number of gasoline also has disadvantages:

• to perform studies, it is necessary to have already identified fuel;
• the effect of external factors can greatly distort the measurement results;
• the method is unacceptable for measuring the gasolines of different types and produced in different ways;
• each device must be calibrated using reference devices;
• measurements should be carried out with a thorough compliance with the temperature mode given in the device specification.

All devices that measure PF use a similar measurement principle, and therefore their advantages and disadvantages are generally identical. Note that the octane number may be greater than 100 due to the inclusion of certain additives in gasoline, but none of such devices are able to work with such liquids.

One of the most affordable octaneometrs is the domestic development of octis, which can be purchased approximately for 3,500 rubles. The German Digatron device is more accurate and relied, but it costs several times higher, about 600 euros. Nevertheless, it is he who is considered the most popular in the Russian market. For his work, it is necessary for reference fuel, which is compared with the studied, and on the basis of this are conclusions about the octane number of the latter. The disadvantage of this octaneometer, as well as other analogs, is that for each measured gasoline from different manufacturers, an appropriate reference sample will be required, since in this case the calibration dependence between Och and dielectric constant will differ. In addition, each measurement must be accompanied by the implementation of calibration procedures, which also affects the accuracy of measurements and the reliability of the results obtained.

A fairly expensive, but efficient Russian-made instrument is octane meter Okan-im (45-50 thousand rubles). Among its features is the presence of built-in memory that allows you to store up to 10 calibrations. The accuracy of the device does not cause complaints.

The PE-7300 M device enters the same price category, and its "chip" is a branded software that allows you to conjugate with a computer / laptop. The octaneometry is able to take into account the temperature factor, which increases the accuracy of measurements (the dielectric constant has a weakly pronounced dependence on ambient temperature).

Approximately the same functionality is laid in the SHATOX SX-100M device worth about $ 1800. It is equipped with a temperature sensor and therefore measures this figure more precisely than the PE-7300, which makes it a purely programmatory way. Regardless of whether you measure the octane number 92 or 95 of gasoline, with a reference fuel sample, the results must coincide with the required accuracy, but within one batch of gasoline. Other deliveries, even from the same manufacturer, may require additional calibration of the device.

Compression ratio and very

All possible varieties of gasolines are characterized by a very specific indicator of the compression ratio, which is governed by GOST. You can get acquainted with the correspondence of the octane number of compression ratio from the following table:

Name of gasoline	Och		GOST	Compression ratio
	Oph.	Ochm.
A72.		72	208477	7.00
A76.		76	208477	7.50
AI80.	80	76	5110597	8.00
AI91	91	82.5	FS 5110597.	9.00
Ai92.	92	83	TU 38001168/97.	9.20
Ai93.	93	85	208477	9.30
AI95	95	85	FS 5110597.	9.50
AI96	96	85	TU 38001168/97.	9.60
Ai98.	98	87	FS 5110597.	10.00

Currently, in the network of domestic gas stations, gasoline grades 76/80 will no longer meet. However, the technique calculated precisely on these varieties of gasoline is still available and, as we noted above, it cannot work on gasoline with a higher octane number. So the need for low-octane gasoline is preserved at a fairly stable, albeit relatively low level. The exit from the current situation is there is an artificial decrease in the octane number of gasoline to the required indicators. At home, this is also possible, but approximately enough. If you have, for example, there is a motoblock, released more than 10 years ago, you will need to reduce the octane number from 95 to 80.

The easiest way is to just open. When interacting with air daily, Pts will decline about 0.5 units, so the procedure will take about a month. Obvious minuses of the method - duration. The second, more used method, can be called the dilution of gasoline kerosene. And although it is it is considered the most common in relation to cars operating in low-octane gasoline, its main disadvantage is the complexity of the selection of the required proportion, that is, the accuracy of the method is very low. However, the same can be said about the first method, so in any case, the measurement of the octo with the use of an octaneometer will be required.

How to increase the octane number of gasoline

Opposite situations are found when only 92nd gasoline is available at refueling, and 95/98 is required. In this case, you can try to independently raise the octane number of gasoline, for which a special substance is added to the fuel, the anti-knock is generalized. Consider all the main additives used as an anti-knock. The usual ethyl (methyl) alcohol may well raise the very necessary amount. By adding a liter of alcohol on 10 liters of 92 liters, it is possible to obtain fuel with Och equal to 95. Such a mixture, by the way, will be characterized by a less toxic exhaust composition, but this method has a cons. One of them is considered to increase the pressure of TVS vapor, which leads to an increase in the probability of formation of traffic jams in the fuel line of the car's power supply. The second drawback of the alcohol mixture is an increase in hygroscopicity, which eliminates the possibility of storing fuel for a long time in the open form due to the possibility of accumulating in gasoline of the critical mass of water.

Tetraethylswin has physical characteristics that make it one of the most efficient anti-knock. This is a high viscosity, and a very large booster temperature (about two thousand degrees). For the first time, it was used as a additive that boosts, almost a century ago - in 1921. Allows you to increase OC by 15-17 units. This substance is most often used to increase the octane number of gasoline with their own hands. Unfortunately, Tetraethylswin has shortcomings that limit its application. This is the formation of lead oxide when combustion of diluted fuel. This substance forms a precipitate, settling on the inner surfaces of pistons, valves and other CPG nodes.

To minimize the formation of such a nagar, special substances (diometane, bromoethyl, dibrompropane) are added to the tetraethylswisin, which binds lead combustion products, contributing to the output from the exhaust path.

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