What kind of fuel is suitable for cars? It must be written in the user manual and the fuel tank cover, and the family car is generally 92,95.

Some cars with strong dynamic performance may be marked with No.98 on the manual and fuel tank cover, or it is recommended to use No.98.

This is actually a bit like: the tough guy with a beer barrel on his waist that you see in the gym. He said this thing is protein powder, which we don't need at ordinary times.

How is the engine gasoline label determined?

The label of gasoline indicates the octane number of gasoline, that is, the antiknock performance. This has been said many times before, so I won't repeat it here.

As for the specific brand of gasoline used in the engine, it actually has a lot to do with the compression ratio of the engine.

Compression ratio is an important parameter to measure engine performance, which refers to the ratio of the volume in the cylinder when the piston is at the bottom dead center and the top dead center.

It reflects the extent to which the engine can compress the combustion working medium, and the more it compresses, the more energy it explodes theoretically.

This has nothing to do with spring or ... you just think it's a syringe, right? You press the syringe to the bottom and then pull it out. Can't you get some water? The volume of this section of water is this ratio.

The more intense compression means that when the engine is working, the greater the pressure in the cylinder, the easier it is to knock, and gasoline with better antiknock performance is needed to play its power.

Generally speaking, the greater the compression ratio, the higher the gasoline grade is needed.

Let's take the spring as an example: the harder you press it, the greater the rebound of the spring. Accordingly, the quality of this spring is required to be good, otherwise it is easy to break.

Chang 'an University has a paper entitled "Study on the Antiknock Performance of Vehicle Fuel and Its Detection Methods", which contains data records.

When the compression ratio is between 7.5 and 9.5, the octane number will increase by 4 units for every increase of 1 unit.

However, the reference significance of engine compression ratio is not as great as before, mainly because there are many advanced technologies to make engine compression ratio look really beautiful.

It's like: now you watch videos and live broadcasts online, and there are beautiful little sisters and beautiful girls everywhere, right? Of course, we don't know if she added a filter.

For example, Mazda, Toyota and Volkswagen, the so-called "high compression ratio" family cars, mostly use the so-called "Atkinson cycle" to achieve high compression ratio.

This compression ratio is called "geometric compression ratio", which is the ratio of the maximum and minimum volume of the cylinder.

In practical work, at the beginning of the compression stroke, the intake valve will remain open, and some gas will be discharged as the piston rises. The effective compression ratio is not as scary as we look.

It's like saying, you took part in a big eating contest, and "Oh, my God" was eating there. Or you're drinking with someone else. In fact, while you were eating, the hamburger was falling.

When you are drinking, you miss the wine on your mouth, or even you spit it out on purpose. That's almost what it means.

What kind of car is suitable for adding 98 # oil?

Generally speaking, cars with strong power and high compression ratio need gasoline with better antiknock performance.

A model with high compression ratio

Come on, take the super run as an example. The compression ratio of this kind of car is generally high.

Ferrari 8 12 naturally aspirated engine, with a compression ratio of 13.6, which is quite high. The Porsche GT3 RS also has 13.3, which is far beyond the standards of 9 to 1 1 for family cars.

Only 98 # gasoline can give full play to these models. Even if some models can be increased by 95, it will not be bad, but the performance is also discounted.

For example, Porsche's instructions say that using 98 # gasoline can make the engine achieve the best performance and the lowest fuel consumption.

But these fuels are not always available. To tell the truth, it should be noted that when using No.95, the engine knock control system will automatically adjust the ignition timing, which may reduce engine power and increase fuel consumption.

You can use it at a discount.

The most important thing is that although adjusting the ignition timing can suppress knocking, the intensity is small.

There is an article in Journal of xihua university, which records the research on the influence of gasoline with different octane number on turbocharged direct injection gasoline engine.

After adjusting the ignition timing of the engine, the maximum explosion pressure of internal explosion decreases, the crank angle corresponding to the maximum explosion pressure is also delayed, and the expansion ratio of the mixture is also reduced.

The increase of combustion duration and the decrease of combustion speed will lead to the decrease of engine thermal efficiency and combustion tolerance.

Anyway, you don't have to remember so many things, but the power is worse and the fuel consumption is higher.

What does this look like? That is, a person who doesn't eat spicy food suddenly went to Chongqing and Chengdu, and his body does have its own regulating function, so he won't be hospitalized directly after eating a hot pot.

But it is inevitable to have diarrhea in the toilet for a week. That's almost what it means.

Model with ultra-high turbine pressure

In addition to ultra-high compression ratio models, some performance cars with ultra-high turbocharged pressure are also marked in the manual and fuel tank cover: 98.

This is generally the case, and the reason is similar. Ultra-high compression ratio needs high grade, because it is hard to press, high pressure and easy to knock.

Although it seems that the compression ratio of the turbocharged car is not very high, the turbocharger has compressed the air in advance, and the pressure in the cylinder is higher than that of natural inhalation.

This is like: self-priming is an ordinary biscuit, and it doesn't feel anything when you go down a bag; The turbocharger ate compressed biscuits, which didn't look very big. With a little water, my whole stomach will fully swell, and I will soon be full.

The degree of air compression is different, because in the final analysis, it still depends on the pressure. The front is "pressed hard", and now it is "hard for you".

For example, the 2.0T engine of Mercedes-Benz A45 S AMG model has a compression ratio of 9, which sounds unusual, and the turbine pressure is as high as 2. 1Bar.

Ferrari F 154 twin-turbo engine, the turbine pressure is 2.4Bar, which is even worse, and McLaren P 1 is also 2.4Bar.

You know, an ordinary family car, such as BMW B48 engine, the low-power version is only 0.6Bar, and the high-power version is about 1.4Bar.

Volkswagen classic model EA888, high-power version about 1.2Bar.

The supercharging pressure of these performance cars is basically higher than that of family cars 1 times.

Can I use number 98 for my family car?

So now cars with strong power can be increased by 98, and family cars are not very recommended.

Mainly 98, 95, 92, there is only a gap in anti-explosion ability. There is little difference in calorific value, but the flame resistance is the same.

On the contrary, the explosion-proof performance of No.98 is slightly better, which has a little fuel-saving effect.

As I said before, the average fuel consumption per 1 octane number unit is about 1%, and this is not the effect of all cars, so it is impossible to save money anyway.

The State Key Laboratory of Automobile Safety and Energy Conservation of Tsinghua University published a paper, and the vehicle test of the influence of octane number on fuel consumption and emission of modern gasoline vehicles gave a conclusion.

Advanced fuel saving effect is only useful for engines that adopt newer technologies such as supercharging miniaturization and in-cylinder direct injection.

For vehicles with relatively backward engine technology, the change of the label actually has no obvious impact, and the old models don't have to join in this excitement.

Smartphones are very convenient. Your grandparents are both 109 years old. He can basically hear, use the old man-machine and call several family members smoothly.

If you teach him to use other apps, it's hard to say who is embarrassed, right?

What brand of gasoline to add depends on the design of the engine.

So generally speaking, what brand of gasoline a car adds depends on the design of the engine.

Generally speaking, the greater the compression ratio and the higher the turbine pressure, the more high-grade gasoline is needed.

92 for 95, can you save fuel?

The average family car really doesn't need 98, so how do we choose 95 and 92?

A friend said that "No.95 is more fuel efficient than No.92", is it true?

If you add half 92 and half 95 on a whim, will it become 93.945 gasoline? Can I use it?

Is it necessary to add 95 to the family car of 65438+ 10 million yuan? It says 92, and vice versa. It says 95. Can you change it to 92?