Glossary: Fuel number

The rising oil price forces consumers to pay attention to the fuel consumption issue. For gasoline, Will 97 # Be more fuel-efficient than 93? What are the consequences of accidental mixing of the two types of fuel? I believe everyone would like to know.

 

 

 

1. To understand the differences between 93 # And 97 #, it is necessary to first understand some basic concepts:

 

 

 

1. compression ratio:

 

 

 

The first standard for automobile selection of gasoline labels is the engine compression ratio, which is also the core energy-saving indicator of contemporary automobiles. The engine is operated by the cycle of the cylinder "suction-compression-combustion-Exhaust-inhalation". The ratio of the piston's volume at the farthest point of travel to the nearest point is the compression ratio. The best way to reduce the cost of fuel consumption is to increase the engine compression ratio. Increasing the compression ratio only changes the piston stroke. The more powerful the mixed oil and gas compression, the greater the combustion reaction, the more adequate the combustion. However, the compression ratio is not easy to implement, because another indicator must be used together, that is, the anti-explosion performance of gasoline, also known as the octane number, that is, the gasoline label.

 

 

 

2. Knock and Explosion resistance:

 

 

 

It is generally believed that the piston is about 10 degrees after the top point of the stroke, and when the combustion produces the maximum pressure, the maximum force to push the piston is (like a swing, the fastest swing after reaching the highest point ). For example, when 1000 rpm is switched, the combustion process is equivalent to 20 degrees of Crankshaft angle, that is, 10 degrees of ignition in advance, and the engine is the most powerful. By 4000 rpm, the piston is moving fast, and the combustion process is equivalent to 60 degrees of the crankshaft angle. Therefore, the engine needs to be ignited at 50 degrees in advance, ignition is getting ahead of schedule. In the end, it will reach a speed, and the oil and gas will be burned up before ignition. This is the knock.

 

 

 

The gasoline label determines the morning and evening of the knock point, that is, the engine power. The anti-explosion performance of fuel varies with its composition. The higher the anti-explosion performance of fuel, the higher the compression ratio of the engine, and the higher the economy and power of the engine.

 

 

 

It is very difficult to determine the explosion resistance of the fuel, because the explosion resistance of the fuel not only depends on the nature of the fuel, it also varies with the engine type, air-fuel ratio, cooling water temperature, intake temperature, ignition advance angle, and valve timing.

 

 

 

3. octane number -- number:

 

 

 

To evaluate the knock resistance of fuel, two methods are generally used: Motor method and research method. The evaluation is generally performed on a dedicated single-cylinder engine with a variable compression ratio.

 

 

 

The testing conditions stipulated by the motor method are: air inlet temperature 149 ℃, cooling water temperature 100 ℃, engine speed 900 r/min, and the ignition advance angle is 14 ° ~ before the Top Dead Point ~ 26 °. During the test, the tested fuel is used first, and the compression ratio is gradually changed until the standard knock strength is indicated on the knock meter. Then, keep the compression ratio and other conditions unchanged and switch to standard fuel. The standard fuel is a mixture of iso-isoisosilane c8h18 with a high explosion resistance (with a fixed octane number of 100) and an elastic-fuel (with a fixed octane number of 0. Gradually change the ratio of isooctane to n-Geng until the explosion strength of the standard fuel is the same as that of the tested fuel. In this case, the volume percentage of isooctane contained in the standard fuel is the octane number of the tested fuel. High octane, fuel resistance is good, and vice versa.

 

 

 

For example, a fuel has an Octa Number of 80, which means that the fuel has the same anti-explosion performance as the mixture containing isooctane 80% and n-g-20%. This is the evaluation standard for fuel Explosion resistance.

 

 

 

The method of study is the same as that of the motor method, but the test conditions are different. The working conditions stipulated in the study are as follows: the intake temperature is 51.7 ℃, the cooling water temperature is 100 ℃, the engine speed is 600 r/min, and the ignition advance angle is 13 °.

 

 

 

As the motor method imposes more stringent conditions than the research method, the measured octane number is relatively low. The same fuel oil is measured by the motor method with 85 times, which is equivalent to 92 times of the research method; when the motor method is 90, the research method is 97. Currently, the gas station uses the research method of octane number.

 

 

 

In general, there are three ways to increase the gasoline octane number in the factory: first, choose a good raw material and improve the processing technology, such as using the secondary processing technology such as catalytic cracking and reforming. The second is to import high-octane components with excellent anti-explosion performance to the product, such as isooctane, isophenyl, and alkyl benzene. Third, add the antiexplosion agent.

 

 

 

Ii. downgrading and over-standard oil:

 

 

 

No. 93 oil is 5% more expensive than No. 90 oil, but its energy consumption is also about 5% smaller. In theory, the fuel consumption ratio is equivalent to the fuel consumption of kilometers. However, considering the high compression ratio matching with No. 93 oil, secondary combustion and incomplete combustion will occur when the engine uses No. 90 oil, resulting in an additional power loss of 5%-8%, considering a series of consequences such as increasing maintenance fees, reducing vehicle conditions, and reducing service life for vehicles, the cost of downgrading oil will go in.

 

 

 

Gasoline is a liquid that is very volatile. When it is 0 to 30 degrees Celsius, combustible components are still volatile. When the gasoline label is too low, the compressed mixed oil and gas will spontaneously ignite before the ignition, the self-ignited oil and gas will generate a strong explosion, causing the original precise design of the Combustion Program to be out of control. Some gasoline will make a negative contribution, and some will not be completely burned because the combustion process is not synchronized with the piston stroke, serious carbon deposition in the intake valve and cylinder, increased fuel consumption, and bad exhaust. When a car is driving at high speed, the chaotic combustion process will produce continuous knock, which will seriously damage the engine, resulting in spark plugs insulation rupture, excessive electrode combustion, piston cylinder knocking, piston ring stuck to death, valve ablation and other consequences. This "crazy" transmission mode allows your car's transmission mode to work in the "high-frequency rock" state, the consequences can be imagined.

 

 

 

In recent years, 97 # gasoline has been widely used in the domestic market. Some riders also fall into a misunderstanding about the use of gasoline, that is, they are keen to use high-grade gasoline. Even some riders regard the gasoline label as the fuel purity and quality standard. This is incorrect. In fact, the level of the gasoline label only indicates the size of the gasoline octane number, and it must not be confused with the purity and quality. If the engine with No. 93 oil is hard to use No. 97 oil, there will be a "ignment" phenomenon, that is, when it is pressed to the head, it will not be self-ignited, and there will be incomplete combustion.

 

 

 

Iii. domestic gasoline analysis:

 

 

 

According to the current fuel condition in China, many 97 # gasoline actually come from the 90 # gasoline with the addition of isooctane, isoisophenyl, alkyl benzene and other additives as well as MTBE anti-explosion agents, it does not come from improving the catalytic cracking, secondary reforming, and other processing techniques in the production process. 97 # high prices and high profits of oil have led to the abuse of additives by some enterprises. They do nothing to increase the gasoline's octane number, regardless of the comprehensive use of fuel in other aspects, which caused a considerable number of 97 # gasoline to easily cause engine carbon deposition, and even corrosion of the component. At present, these phenomena are often seen in some imported high-end cars, as well as those with ultra-high compression ratios such as Polo, Palio, and the latest new hand-built speedgear series.

 

 

 

Relatively speaking, the processing technology of 90 # and 93 # gasoline in China is relatively good, and the price is relatively low, and the profit is relatively low, as a result, few companies are working on 90 # and 93 # gasoline.

 

 

 

On the other hand, because 90 # gasoline has been widely used for many years, the vast majority of 90 # Gasoline storage and transportation tools and gas station cylinders have been used for many years, accumulating more and more impurities in storage and transportation tools and gas station cylinders, this resulted in the quality problem of 90 # gasoline mainly reflected in the impurity aspect.

 

 

 

While 93 # gasoline has only been widely promoted for more than two years, and the 93 # cylinder of most gas stations is still relatively clean. Therefore, 93 # gasoline is relatively reliable.

 

 

 

In practice, different riders have different experiences and opinions on the use of No. 93 oil and No. 97 oil:

 

 

 

1. 93 schools:

 

 

 

93 and 97 are only different in the octane number and have nothing to do with the cleanliness of the fuel. Therefore, 97 to 93 cleaning is yet to be verified. Only the fuel sources are different and the quality is unstable. In some gas stations, 97 may only meet the 93 standard. 97 and 93 may not necessarily make the car more powerful (or even the opposite), but because the oil is pure, the fuel consumption may be reduced.

 

 

 

2. 97 schools:

 

 

 

97 the oil is better in terms of anti-explosion performance. The engine is relatively soft to use, and there is no feeling of power or fuel consumption. 97 hundred kilometers than 93 provinces and a half oil, the price difference is also found, 97 is quite good! It seems to be more than 93 meat points, but the speed is very smooth, there is not much difference, and 97 seems to be less than 93 fuel. Gix car: 97, the throttling valve, nozzle, oil circuit, cylinder are clean, not much money, he happy. It seems that 97 is more gentle to run. Acceleration and fuel consumption are similar to 93. It's just a personal feeling, and the difference is quite obvious. 97 feels better than 93, but after 97, the fuel consumption is higher than 93 1l, or the road may be poor.

 

 

 

3. Median:

 

 

 

After a while, I felt that 93 was strong, but 97 seemed to be able to run more kilometers. I felt that there was no big difference in the number of kilometers when I spent the same amount of money, and I could not save much money. GTX is changed from 93 # oil to 97 # oil. The increase of 97 is light and fuel-saving, but the speed is not enough. T-Series cars have a higher compression ratio than I-Series cars (of course, it is not as high as 97 oil is required). CT cars: In the feeling of using cars, 97 to 93 speed up a little slower, not bad speed, is a little delay, not as bad as 93, feel it is up. Don't worry too much, but stick to it if you want to add No. 97 oil.

 

 

 

Finally, we recommend that you add fuel according to the requirements of the user manual. Otherwise, the manufacturer will be troubled by maintenance problems! We recommend that you use 97 # oil for high-end imported vehicles. For domestic medium-grade vehicles, 93 # oil is sufficient. Accidentally mixed two types of fuel, the problem is not big, after use back to the original oil number can be.