Characterized by a number of values. One of them is the compression ratio of the engine. It is important not to confuse it with compression - the value of the maximum pressure in the engine cylinder.
What is compression ratio
This degree is the ratio of the volume of the engine cylinder to the volume of the combustion chamber. Otherwise, we can say that the compression value is the ratio of the volume of free space above the piston when it is at bottom dead center, to the same volume when the piston is at the top point.
It was mentioned above that compression and compression ratio are not synonymous. The difference also applies to designations, if compression is measured in atmospheres, the compression ratio is written as a ratio, for example, 11:1, 10:1, and so on. Therefore, it is impossible to say exactly what the compression ratio in the engine is measured in - this is a "dimensionless" parameter that depends on other characteristics of the internal combustion engine.
Conventionally, the compression ratio can also be described as the difference between the pressure in the chamber when the mixture is supplied (or diesel fuel in the case of diesel engines) and when the fuel portion is ignited. This indicator depends on the model and type of engine and is due to its design. The compression ratio can be:
- high;
- low.
Compression calculation
Consider how to find out the compression ratio of an engine.
It is calculated by the formula:
Here, Vp means the working volume of an individual cylinder, and Vc is the value of the volume of the combustion chamber. The formula shows the importance of the camera volume value: if, for example, it is reduced, then the compression parameter will become larger. The same will happen in the case of an increase in the volume of the cylinder.
To find out the displacement, you need to know the cylinder diameter and piston stroke. The indicator is calculated by the formula:
Here D is the diameter and S is the piston stroke.
Illustration:
Since the combustion chamber has a complex shape, its volume is usually measured by pouring liquid into it. Knowing how much water fit in the chamber, you can determine its volume. For determination, it is convenient to use water because of the specific gravity of 1 gram per cubic meter. cm - how many grams are poured, so many "cubes" in the cylinder.
An alternative way to determine the compression ratio of an engine is to refer to its documentation.
What affects the compression ratio
It is important to understand what the compression ratio of the engine affects: compression and power directly depend on it. If you make the compression more, the power unit will receive greater efficiency, since the specific fuel consumption will decrease.
The compression ratio of a gasoline engine determines what octane rating it will consume. If the fuel is low octane, this will lead to an unpleasant knocking phenomenon, and too high an octane number will cause a lack of power - a low compression engine simply cannot provide the necessary compression.
Table of the main ratios of compression ratios and recommended fuels for gasoline internal combustion engines:
| Compression | Petrol |
| To 10 | 92 |
| 10.5-12 | 95 |
| From 12 | 98 |
Interestingly, turbocharged gasoline engines run on fuel with a higher octane rating than similar naturally aspirated ICEs, so their compression ratio is higher.
Diesels have even more. Since high pressures develop in diesel internal combustion engines, this parameter will also be higher for them. The optimum compression ratio for a diesel engine is between 18:1 and 22:1, depending on the unit.
Changing the aspect ratio
Why change degree?
In practice, this need rarely arises. You may need to change the compression:
- if desired, force the engine;
- if you need to adapt the power unit to work on non-standard gasoline for it, with an octane number different from the recommended one. This was done, for example, by Soviet car owners, since there were no kits for converting a car to gas for sale, but there was a desire to save on gasoline;
- after an unsuccessful repair, in order to eliminate the consequences of incorrect intervention. This may be a thermal deformation of the cylinder head, after which milling is needed. After the compression ratio of the engine has been increased by removing a layer of metal, it becomes impossible to work on gasoline originally intended for it.
Sometimes the compression ratio is changed when converting cars to run on methane fuel. Methane has an octane number of 120, which requires increasing the compression for a number of gasoline cars, and lowering it for diesels (SG is in the range of 12-14).
Converting diesel to methane affects power and leads to some loss of power, which can be compensated by turbocharging. A turbocharged engine requires an additional compression reduction. It may be necessary to refine the electrics and sensors, replace the diesel engine injectors with spark plugs, and a new set of cylinder-piston groups.
Forcing the engine
In order to produce more power or to be able to run on cheaper grades of fuel, the internal combustion engine can be boosted by changing the volume of the combustion chamber.
To obtain additional power, the engine should be boosted by increasing the compression ratio.
Important: a noticeable increase in power will be only on the engine that normally operates with a lower compression ratio. So, for example, if a 9:1 ICE is tuned to 10:1, it will produce more extra horsepower than a stock 12:1 engine boosted to 13:1.
The following methods are possible, how to increase the compression ratio of the engine:
- installation of a thin cylinder head gasket and refinement of the block head;
- cylinder bore.
By finalizing the cylinder head, they mean milling its lower part in contact with the block itself. The cylinder head becomes shorter, which reduces the volume of the combustion chamber and increases the compression ratio. The same happens when installing a thinner gasket.
Important: these manipulations may also require the installation of new pistons with enlarged valve recesses, since in some cases there is a risk of piston and valves meeting. The valve timing must be reconfigured.
Boring the BC also leads to the installation of new pistons to the appropriate diameter. As a result, the working volume increases and the compression ratio increases.
Deforcing for low-octane fuel
Such an operation is carried out when the issue of power is secondary, and the main task is to adapt the engine to another fuel. This is done by lowering the compression ratio, which allows the engine to run on low-octane gasoline without knocking. In addition, there is a certain financial savings on the cost of fuel.
Interesting: a similar solution is often used for carburetor engines of old cars. For modern electronically controlled injection internal combustion engines, deforcing is highly discouraged.
The main way to reduce the compression ratio of the engine is to make the cylinder head gasket thicker. To do this, take two standard gaskets, between which an aluminum gasket-insert is made. As a result, the volume of the combustion chamber and the height of the cylinder head increase.
Some interesting facts
Race car methanol engines have a compression ratio of over 15:1. In comparison, a standard carbureted engine running unleaded gasoline has a maximum compression ratio of 1.1:1.
Of the serial samples of engines on gasoline with a compression of 14: 1, there are samples from Mazda (Skyactiv-G series) on the market, which are installed, for example, on the CX-5. But their actual CO is in the range of 12, since these motors use the so-called "Atkinson cycle", when the mixture is compressed 12 times after the late closing of the valves. The efficiency of such engines is not measured by compression, but by the expansion ratio.
In the middle of the 20th century, in the world engine building, especially in the USA, there was a tendency to increase the compression ratio. So, by the 70s, the bulk of the samples of the American automobile industry had an SJ from 11 to 13: 1. But the regular operation of such internal combustion engines required the use of high-octane gasoline, which at that time could only be obtained by the ethylation process - the addition of tetraethyl lead, a highly toxic component. When new environmental standards appeared in the 1970s, ethylation began to be banned, and this led to the opposite trend - a decrease in coolant in serial engine models.
Modern engines have an automatic ignition angle control system that allows the internal combustion engine to operate on "non-native" fuel - for example, 92 instead of 95, and vice versa. The UOZ control system helps to avoid detonation and other unpleasant phenomena. If it is not there, then, for example, filling in a high-octane gasoline engine that is not designed for such fuel can lose power and even fill the candles, since the ignition will be late. The situation can be corrected by manually setting the UOZ according to the instructions for a specific car model.
Automotive fuel is a low-boiling hydrocarbon fraction (33–205°C) of direct oil refining. The key parameters of gasoline are compression ratio and octane number. Modern automobile gasolines are marked with the designations "AI" and digital indices 80-98. Depending on the specific type of engine, a certain brand of gasoline is used. Let us analyze the main characteristics of automotive liquid fuel in more detail.
Compression ratio - self-ignition resistance
The physical ratio of the total volume of the cylinder at the moment the piston is in the dead center to the working volume of the internal combustion chamber is characterized by the compression ratio (CL). The indicator is described by a dimensionless quantity. For gasoline drives it is 8–12, for diesel drives it is 14–18. Increasing the parameter increases power, engine efficiency, and also reduces fuel consumption. However, high CV values increase the risk of self-ignition of the combustible mixture at high pressure. For this reason, gasoline with a high coolant index must also have high knock resistance - octane number (OC).
Octane number - knock resistance
Premature combustion of gasoline is accompanied by a characteristic knock caused by detonation waves inside the cylinder. A similar effect is due to the low resistance of liquid fuel to self-ignition at the time of compression. Knock resistance is characterized by an octane number, and a mixture of n-heptane and isooctane was chosen as a reference. Commercial grades of gasoline have an octane value in the region of 70–98, which corresponds to the percentage of isooctane in the blend. To increase this parameter, special octane-correcting additives are introduced into the mixture - esters, alcohols, and less often heavy metal ethylates. There is a relationship between the compression ratio and the brand of gasoline:
- In the case of CV less than 10, AI-92 is used.
- With CV 10–12, AI-95 is required.
- If CV is 12–14 - AI-98.
- With CV equal to 14, you will need AI-98.
For a standard carbureted engine, the SOL is approximately 11.1. In this case, the optimal OC is 95. However, methanol is used in some racing types of cars. The SD in this example reaches 15, and the OC varies from 109 to 140.
Use of low octane gasoline
The car manual indicates the type of engine and the recommended fuel. The use of a combustible mixture with a low OC leads to premature burnout of the fuel and sometimes the destruction of the structural elements of the motor.
It is also important to understand which fuel supply system is used. For a mechanical (carburetor) type, compliance with the requirements for OC and SJ is mandatory. In the case of an automatic or injection system, the air-fuel mixture is adjusted electronically. The gasoline mixture is saturated or depleted to the required OCH values, and the engine is running normally.
High octane fuel
AI-92, as well as AI-95 - the most used brands. If you fill the tank, for example, with the 95th instead of the recommended 92nd, there will be no serious damage. Only the power will increase within 2-3%. If you fill the car with 92 instead of 95 or 98, then fuel consumption will increase, and power will decrease. Modern cars with electronic injection control the supply of a combustible mixture and oxygen and thereby protect the engine from undesirable effects.
Table of compression ratio and octane number
The knock resistance of automotive fuel has a direct relationship with the compression ratio, which is presented in the table below.
Conclusion
Motor gasolines are characterized by two main characteristics - knock resistance and compression ratio. The higher the SO, the more OC is required. The use of fuel with a lower or higher value of knock resistance in modern cars will not harm the engine, but will affect the power and fuel consumption.
Everyone knows that in gasoline piston internal combustion engines, the air-fuel mixture is compressed before ignition. A similar cycle of operation of diesel engines differs only in that air is compressed without fuel. One of the most important characteristics of both internal combustion engines is the compression ratio. It shows how many times the volume of space above the piston bottom changes when it passes from the bottom dead center to the top.
Sometimes this indicator is confused with compression, despite the fact that the difference between them is huge. After all, the characteristics mentioned above, although related, in fact, are completely different. What even their dimensions indicate. The compression ratio is a ratio such as 10:1 or just 10 and has no units. That is, it is measured in "times". Compression, on the other hand, shows the maximum pressure of the mixture in the cylinder before ignition and is measured in kg / cm2. So, the compression of an internal combustion engine with a compression ratio of 10: 1 should be no more than 15.8 kg / cm2. It is possible to say what the degree of compression is in another way. This is the ratio of the volume above the piston at bottom dead center to the volume of the combustion chamber. The combustion chamber is the space above the piston that has reached top dead center.
Calculation of the compression ratio
You can calculate the compression ratio of an internal combustion engine if you perform the calculation using the formula ξ = (Vр + Vс) / Vс; where Vp is the working volume of the cylinder, Vc is the volume of the combustion chamber. It can be seen from the formula that the compression ratio can be made larger by reducing the volume of the combustion chamber. Or by increasing the working volume of the cylinder without changing the combustion chamber. Vp is much larger than Vc. Therefore, we can assume that ξ is directly proportional to the working volume and is inversely related to the volume of the combustion chamber.
The working volume of the cylinder can be calculated by knowing the diameter of the cylinder - D and the piston stroke - S. The formula for calculating it looks like this: Vр = (π*D2/4)* S. 
The volume of the combustion chamber, due to its complex shape, is usually not calculated, but measured. You can do this by pouring liquid into it. You can determine the volume that fits into the liquid chamber using measuring utensils or scales. For weighing, it is convenient to use water, since its specific gravity is 1 g per cm3. So, its weight in grams will show the volume in a cube. cm.
The influence of the compression ratio on the characteristics of the motor
The higher the compression ratio, the greater the compression of the internal combustion engine and its power (ceteris paribus). By increasing the compression ratio, we also contribute to an increase in engine efficiency by reducing specific fuel consumption. The compression ratio of an internal combustion engine determines the octane rating of the gasoline used to run the engine. So, low-octane fuel will cause engine detonation with a large value of this coefficient. Excessively high octane fuel will not allow the power unit, the compression of which is low, to develop full power.
Initial data
The octane number of the fuel used for gasoline engines with different compression ratios.
Alignment of the mating plane of the head with the block by cutting off the metal layer leads to a decrease in the combustion chamber of the motor. From this, the compression index increases by an average of 0.1 with a decrease in head thickness by 0.25 mm. With this data at your disposal, you can determine whether it will exceed the permissible limits after repairing the block head. And should measures be taken to reduce it? Experience shows that when removing a layer of less than 0.3 mm, the consequences may not be compensated.
Why is it necessary to change the compression ratio
The need to change this parameter of the internal combustion engine occurs quite rarely. There are just a few reasons why this could be done.
How can I change the compression ratio
Enlargement Methods:
- Boring cylinders and installing larger pistons.
- Reducing the volume of combustion chambers. It is carried out by removing a layer of metal from the side of the plane of mating the head with the block. Due to the softness of aluminum, this operation is best done on a milling or planing machine. A grinder should not be used, as its stone will be constantly clogged with ductile metal.
Ways to reduce:
- Removing a layer of metal from the bottom of the piston (this is usually done on a lathe).
- Installation between the head and the cylinder block of a duralumin spacer between two gaskets.
Relationship between compression ratio and compression
Knowing the value of the compression ratio, you can calculate what compression should be in the engine. However, the reverse estimate will not be true. 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 significant engine wear and the need for repair, and not a low compression ratio.
turbocharged engines
In the cylinders of a turbocharged engine, air is pumped by a compressor at a pressure slightly higher than atmospheric pressure. So, to determine the compression ratio of such a motor, you need to multiply the value that you get as a result of the calculation by the formula by the turbocharger coefficient. Turbocharged gasoline engines run on fuel with an octane rating higher than that of gasoline, which is consumed by the same engines without turbines, precisely because their ξ factor is greater.
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Which gasoline is better to pour 92 or 95. A few words about the octane number and compression ratio. Really helpful stuff
I think many are asking this question in the vastness of the endless Russian roads. What kind of gasoline is better to pour into your iron horse 92 or 95? Is there a critical difference between them, and what will happen if 92 gasoline is used instead of 95? After all, it is cheaper by about 5 - 10%, and accordingly, there will be real savings from each tank! BUT is it worth it to do this and is it not dangerous for your power unit, let's take it apart, there will be a video version and a vote at the end.
At the very beginning, I suggest thinking about what these numbers are, 80, 92, 95, and in Soviet times also 93? Never thought? It's all just octane. And then what is it? Read on.
Octane number of gasoline
The octane number of gasoline is an indicator that characterizes the knock resistance of a fuel, that is, the value of the fuel's ability to resist self-ignition during compression for internal combustion engines. That is, in simple words, the higher the "octane level" of the fuel, the less likely it is to self-ignite the fuel during compression. In such a study, fuel levels are distinguished by this indicator. Research is carried out on a single-cylinder unit with a variable fuel compression level (they are called UIT-65 or UIT-85).
The units are running at 600 rpm, the air and mixture is 52 degrees Celsius, and the ignition timing is about 13 degrees. After such tests, OCHI (research octane number) is derived. This study should show how gasoline will behave at minimum and medium loads.
At maximum fuel loads, there is another experiment that displays (OCM - engine octane number). The tests are carried out on this single-cylinder unit, only 900 rpm, air and mixture temperature of 149 degrees Celsius. MON is lower than RON. During the experiment, the level of maximum loads is displayed, for example, during throttle acceleration or when driving uphill.
Now I think at least a little it became clear what it is. And how is it defined.
Now let's get back to the choice - 92 or 95. Any kind, be it 92 or 95, and even 80. When it is processed at the plant, it does not have such a finite octane number. With direct distillation of oil, only 42 - 58 is obtained. That is, very low quality. "How so" - you ask? Is it really impossible to overtake immediately with a high rate? It is possible, but it is very expensive. A liter of such fuel would cost several times more than those currently on the market. The production of such fuel is called catalytic reforming. Only 40 - 50% of the total mass is produced in this way, and mainly in Western countries. In Russia, much less gasoline is produced in this way. The second production technology, which is less expensive, is called catalytic cracking or hydrocracking. Gasoline with this treatment has an octane rating of only 82-85. In order to bring it to the desired indicator, you need to add special additives to it.
Additives in gasoline
1) Additives based on metal-containing compounds. For example, on tetraethyl lead. Conventionally, they are called leaded gasolines. Very efficient, they make the fuel work, for the whole, as they say. But also very harmful. As you can see from the name tetraethyl lead, the composition contains metal - "lead". When burned, it forms 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 banned worldwide. In the USSR, there was a brand AI - 93, it was just based on tetraethyl lead. It is conditionally possible to call this fuel obsolete and harmful.
2) More advanced and safer ones are based on ferrocene, nickel, manganese, but monomethylaniline (MMNA) is most often used, 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 ideal, they form plaque on pistons, candles, clog catalysts and all kinds of sensors. Therefore, sooner or later, such fuel will clog the engine, in the truest sense of the word.
3) The latest and most perfect are ethers and alcohols. The most ecological and do not harm the environment. But there are also disadvantages of such fuel, this is a low octane number of alcohols and ethers, the maximum value is 120 points. Therefore, quite a lot of such additives, about 10 - 20%, are required in the fuel. Another drawback is the aggressiveness of alcohol and ether additives; with a high content, they quickly corrode rubber and plastic pipes and sensors. Therefore, such additives are limited within 15% of the total fuel level.
Compression ratio and modern car
Actually, why I started talking about the octane number and additives, but because self-ignition of fuel or the so-called detonation in modern units must be taken into account.
The fact is that manufacturers, in order to increase power and reduce fuel consumption, slightly increase the compression ratio in the engine cylinders.
Here is some useful information:
For a compression ratio of up to 10.5 and below, the octane number of AI gasoline is used - 92 (we do not take into account TURBO engine options).
From a mark of 10.5 to 12 - fill in fuel not lower than AI - 95!
Of course, there are still very rare gasolines, such as AI - 102 and AI - 109, for which the compression ratio is 14 and 16, respectively.
So what would happen, IN THEORY, if we poured 92 petrol into an engine that was designed for 95? YES, everything is simple, the fuel from a high compression ratio will spontaneously ignite, “mini-explosions” will occur - that is, a destructive detonation effect will appear!
Why is detonation dangerous? Yes, everything is simple, burnout of the gasket between the block head and the block itself, destruction of rings (both compression and oil scraper), burnout of pistons, etc.
BUT it's like I wrote above - ALL THIS IS IN THEORY! ESPECIALLY IN RUSSIA! Why am I saying this. Many manufacturers have realized that it is VERY DIFFICULT to find high-quality gasoline (and now we are talking about the 95th option), if possible, even in the metropolitan regions (I am already silent about small towns). Often, gasoline is “bad” so that an octane rating of 95 is unrealistic to achieve. I remember a couple of years ago, I read an article with an experiment - where samples were taken from a large number of gas stations in the capital, and only in 20 - 25% of cases gasoline approached the norms, the rest were far from the figure 95 and even 92. Just think about it! How do you check the quality yourself? That's right - NOTHING.
So if you fill in such low-quality fuel, the engine will immediately shut down? Straightaway? Not certainly in that way. Cars are smart now, and it was to prevent your engine from going “overheated” that a knock sensor was invented, it allows the engine to work with a different octane number. It monitors the mechanical vibrations of the engine block, converts them into electrical impulses and constantly sends them to the ECU.
If the pulses "go beyond the normal state", then the ECU decides to correct the ignition angle and the quality of the fuel mixture. Thus, a modern engine designed for 95 gasoline will work quietly even at 92.
However! Such work will be successful at low and medium speeds, at high speeds (almost maximum), the knock sensor does not work as efficiently, so it is UNDESIRABLE to “fry” on a low-octane mixture!
Let's summarize.
What happens if you fill in 92 instead of 95?
In fact, the difference between 92 and 95 gasoline is minimal, only "3 numbers". If you refuel in a company that guarantees you precisely “hard indicators”, that is, “92 is 92”, and “95 is 95”, and YOU WILL BE SURE OF THIS. That difference will show for your engine rather at high speeds, and not in a significant (up to 2 - 3%) loss of power, and fuel consumption will also increase by this percentage.
And what is most interesting, if you do not often spin your power unit up to 5000 - 7000 rpm, but move from 2000 to 4000, then 92 will not give you any negative points. The electronics will take care of everything by itself.
Prejudices - that valves can burn out, there is no such thing. Valve burnout was common with leaded types that had metal additives. High-octane leaded gasolines could harm an engine tuned to use the AI-76 (and it did not have electronic correction of the ignition angle and fuel injection). But now there is simply no such danger, because such fuel has long been banned.
BUT IDEAL! Use the exact fuel recommended by your manufacturer. After all, if suddenly a new engine breaks down, and it turns out that the breakdown is related to gasoline, then you will find yourself in a very expensive repair, AND AT YOUR OWN ACCOUNT. Saving 10% on gasoline will come out sideways to you.
What final result you want to bring out - to each his own, if your motor is not designed for the 92nd, then you should not pour it! However, it can be dangerous! However, if you fill it with a modern engine, it automatically adjusts the ignition angles and you may not even feel the fuel change (THE IS AND YOU CAN RIDE THE 92nd without spinning your engine to the maximum). But if a breakdown occurs, and the warranty finds out that the wrong fuel is filled in, REPAIR WILL BE AT YOUR ACCOUNT! And this, for sure, is not worth 2 - 3 rubles of savings per liter.
Now a detailed video version, look.
The octane rating is the ability of a fuel to resist detonation and is called the octane rating. The higher it is, the higher this resistance is. Therefore, low octane gasolines are used in low compression engines and high octane gasolines in high compression engines.
Often the question arises: gasoline with what octane number (OC) can be poured into the engine, given our quality of gasoline.
Everything is simple. We open the filler flap of your car or the car's operating instructions and read what kind of gasoline is indicated there, and this can be filled in. Check the manual for the compression ratio.
Compression ratio and octane number of atmospheric gasoline engine
1. If the compression ratio is 12 and higher, fill it with at least AI-98.
2. If the compression ratio is 10 and up to 12 - fill in at least AI-95.
The volume of the combustion chamber with such a compression ratio is made exactly for this number.
92, as it were, it is possible to fill in, but it is not necessary, the consumption will be more.
3. If the compression ratio is below 10, fill in the AI-92 octane number (except for the turbo).
Exotic AI-102 and AI-109 - from 14 and from 16, respectively.
For turbo engines at least AI-95 and above!
Do not confuse the compression ratio with the compression in the engine cylinders.
Compression ratio- this is a geometric dimensionless quantity, calculated as the ratio of the total volume of the cylinder to the volume of the combustion chamber.
Compression- This is a physical quantity, the pressure in the cylinder at the end of the compression stroke. It is measured in atmospheres or kg / cm2 when scrolling with a starter on a well-charged battery and unscrewed candles for measurement.
The optimal compression of the motor is very approximately calculated by multiplying the compression ratio by 1.4 atmospheres.
- If you use fuel with a lower octane, then impact loads in the form of detonation knocks and ringing will inevitably increase, and as a result, engine wear. In addition, the consumption is higher and the meaning of saving is lost.
- 2. If you use gasoline with a higher octane ratio than is provided for by the engine design, then gasoline will burn longer, giving off more heat.
- Higher octane fuels tend to burn at lower temperatures and more slowly. Due to the combustion rate lower than the calculated one, it may happen that during the exhaust phase, a still burning mixture will be released through the valve instead of the exhaust gases. Consequently, engine parts will overheat, especially valves, and oil consumption will also increase. Interestingly, by ear, the engine often starts to run quieter and smoother (due to thermal expansion, gaps are selected), but at the same time, the engine runs for wear.
- For example, 100th gasoline burns too slowly for your compression ratio. Therefore, it does not burn out completely and smokes. It makes no sense to fill in the 100th if the car rides well on the 95th.
Higher octane fuels are more resistant to detonation.
If the engine does not have a ignition angle control system, then flooding with high-octane fuel can ruin the spark plugs again and lose some power, as there will be a late ignition.
Petrol- what's happened
Gasoline is the lightest of the liquid fractions of oil (a mixture of light hydrocarbons). It is used as a fuel in carburetor and injection engines of modern cars, motorcycles and other equipment.
Gasoline labeling
In accordance with GOST 54283-2010 in Russia, there is a single marking for all gasolines. For example, AI-80. It is decoded like this. A - motor gasoline, I - octane number determined by the research method. 80 is the octane number itself. Also, at the end, another number can be added to the name - the environmental class of the fuel, from 2 to 5, (for example, AI-92/4). If the letter And is not in the marking of gasoline, then its octane number is determined by the motor method (A-92).
The requirements for the quality of gasoline currently produced are determined by the Technical Regulations adopted in 2011. The full name is "On the requirements for automobile and aviation gasoline, diesel and marine fuel, jet fuel and heating oil."
Gasoline types
Unleaded gasoline
Gasoline without additives containing lead. All gasoline currently produced in accordance with the Technical Regulations.
Gasoline AI-80
The full name is "Gasoline AI-80, Normal". Octane number 80, obtained by research method. According to the motor method, it is 76. The quality corresponds to GOST 51105-97. Fuel class - the second. Not leaded.
Gasoline AI-92
The full name is "Gasoline AI-92/4, Regular". Octane number 92, according to the research method, 83 - according to the motor method. GOST 51105-97. Not leaded.
Gasoline AI-95
The full name is "Gasoline AI-95/4, Premium Euro". Octane number - 95 according to the research method, 85 - according to the motor. GOST 51105-97. Not leaded.
Gasoline AI-98
The full name is “Gasoline AI-98/4, super-euro. The octane number is 98 by the research method, 88 by the motor method. Produced according to TU-38.401-58-122-95, TU-38.401-58-127-95, TU-38.401-58-350-2005. Not leaded.
Gasoline A-92
The octane number is determined by the motor method = 72. Corresponds to GOST 2084-77. Currently out of production. Not leaded.
Gasoline AI-76
Corresponds to AI-80. Octane number according to the motor method = 76. Produced in accordance with GOST 2084-77. Could be either leaded or unleaded.
Gasoline AI-91
Corresponds to AI-92. Research octane rating 82.5. It was produced according to GOST 51105-97. Not leaded.
Gasoline A-92
Produced according to TU 38.001165-97. According to TU 38.001165-87, in Soviet times it was exported. Analog AI-92. Not leaded.
Gasoline AI-93
Corresponds to AI-95. Octane number according to the motor method 82.5. According to the research 93. In the days of the USSR, gasoline marked A-93 was exported, and for the domestic market it was called AI-93. Could be leaded and unleaded.
