What grade of gasoline to add to a car has been determined at the beginning of the design of the car, what kind of compression ratio to use, how to adjust the computer program to achieve the best state, and will make corresponding adjustments according to the model of gasoline, also known as engine tuning. How do I know what grade of petrol my car is in? Generally, you can see when you open the fuel tank cap, and it is clearly written on it, please add a few gasoline numbers. It is also written on the B-pillar of some cars and in the user manual. Under normal circumstances, we can add whatever label the manufacturer requires to add, and there is no need to increase the label, and of course, the label can not be lowered.
In the actual process of using the car, some car owners have such an experience, and their cars have always been filled with 92 gasoline. Occasionally, if you add 95 gasoline, you can have a clear feeling, adding 95 gasoline is more powerful, and fuel consumption will be reduced, what is going on? There are three reasons for this.
The first is its own psychological effect, because 95 gasoline is more expensive, it will always be considered that it is of better quality and higher quality. Therefore, after refueling, you will feel that the car is particularly energetic, in fact, the same is true for adding 92 gasoline, just after refueling, within a few kilometers of driving out of the gas station, you will feel that the car is obviously more energetic, which is caused by the change of fuel tank pressure, of course, there are also psychological factors.
The second is the effect of the compression ratio. The compression ratio of the engine was originally very high, but in fact, it should be added with No. 95 oil to meet the demand. However, for the sake of cost considerations and better sales of the car, the manufacturer will deliberately make some adjustments and adjust an engine with a high compression ratio to be able to add 92 gasoline. Therefore, when requesting the gasoline model, it will be written that please add 92 and higher gasoline, that is, the minimum is 92, and 95 is OK. This kind of vehicle plus 95 may make the power stronger, and the fuel consumption will also be reduced. Because the 95 is more suitable for the car, so that the gasoline burns safer and gives full play to its performance. However, the difference in fuel consumption is not too big, only a slight difference. For example, if you add 200 yuan, the number of kilometers traveled may be the same, although it saves fuel but does not save money.
Speaking of which, it is necessary to understand the concept of octane number. The biggest difference between 92 and 95 gasoline is the octane number, and the 95 has a higher octane number. It can be understood that the higher the octane number, the less likely it is to burn, and the lower the octane number, the easier it is to burn. If the compression ratio of the engine is very high, the fuel mixture will be compressed very badly. It's like a needle, plugging the head and pushing the piston forward. Suppose pushing forward one centimeter is 1 and pushing two centimeters is 2. A significant push of two centimeters will compress the air more, which means that the compression ratio is higher.
The more the fuel mixture is compressed, the higher the temperature generated, and the higher the temperature will become, and it will become a high-temperature and high-pressure mixture. If you add 92 gasoline and it burns too easily, then there may be a situation where the spark plug burns on its own before it is ignited. As a result, it is not burned at the best time, and the energy burned is wasted, and it is not used to do work. And if you add No. 95 gasoline, it has a high octane number, and it is not easy to burn itself, and it can only burn after being ignited by a spark plug. In this way, the work can be burned according to the combustion time set by the engineer, so that the energy generated by gasoline combustion can be used to maximize the work to promote the piston to run. It will have plenty of power and low fuel consumption.
After the octane number is understood, there is one last case, that is, there is too much carbon on the top of the piston, and adding 95 gasoline power will improve significantly. When there is no carbon deposit, the compression ratio is not large, and it is very suitable to add 92 gasoline. When there is carbon deposit, the carbon deposit occupies the space of the combustion chamber, resulting in a change in the compression ratio, and at the same time, the carbon deposit will also absorb fuel vapor, resulting in insufficient combustion, it will feel that the power will decrease, and of course the fuel consumption will also increase. Because there is carbon deposit on the top of the piston, the compression ratio will also become larger, and at this time, 95 gasoline is added, which can just meet the current compression ratio, so the power will be improved, and the fuel consumption will be reduced a little.
However, this power increase is compared with when there is carbon deposition, because there is carbon deposition, the power of adding 92 has decreased, the fuel consumption has increased, and the power has increased only after adding 95. If it is compared to the time when there was no carbon deposit, the current power may not be as strong as the power of the previous No. 92 gasoline. Therefore, don't make the mistake of thinking that you don't need to clean it if you have carbon deposits, just add higher grade gasoline. Carbon deposits need to be cleaned up in time so that the engine is at its best level and the cheap No. 92 oil can perform at its best. If the carbon deposit is not washed for a long time, it is very difficult to clean it after accumulating a lot, and it may be necessary to disassemble and wash the engine, which is very expensive.
Source: Autopedia