Cars suggest 92% fuel, why not 95% fuel? What is the difference?

The fundamental problem is not' 92' or' 95'. There are no labels on gasoline in many foreign gas stations, but it still has certain China characteristics in China. I just heard the description of the industry from hearsay. As for authenticity, interested friends can personally test and compare. Adding' 95' gasoline will not affect the car, and it is no problem to mix it with or switch back to' 92' gasoline. Only 92 # gasoline is recommended, but 95 # gasoline is not recommended, which will not affect the quality of the engine, but will accelerate the formation of carbon deposits and reduce the dynamic performance. The difference between different grades of gasoline is density and octane number, and different octane number changes the evaporation and ignition point of gasoline.

The compression stroke of the engine is used to heat gasoline. Evaporation and heating temperature determine the ignition efficiency of spark plug after ignition. After upgrading to 95 # gasoline, the set compression stroke can't effectively heat the fuel, which leads to the incomplete combustion of some mixed oil and gas after ignition and direct discharge. After the free carbon is mixed with engine oil vapor, the unburned oil and gas will form carbon deposit, and the conversion efficiency of mechanical energy will reduce the power. After being degraded from high grade to low grade, knocking will occur. In the process of compression, gasoline only needs to be heated, but the ignition point will also change with the change of octane number ratio. Therefore, the high temperature with high compression ratio will directly ignite a part of high-temperature rich fuel. When it should not be burned, the explosion will produce vibration, and the continuous vibration will lead to the wear of the piston and cylinder, thus damaging the engine.

As we all know, the octane number in gasoline directly depends on the proportion of various hydrocarbons in gasoline. For example, n-heptane can easily cause detonation. The octane number is zero, the knock of isooctane is small, and the octane number is 100. Why use some engines? 95# gasoline is needed for 92# gasoline? In fact, the demand for anti-explosion ability is different. Similarly, the evaluation index of engine antiknock ability is also compression ratio. Compression ratio refers to the ratio of the volume of cylinder piston at the lowest point to the volume of cylinder piston at the highest point. The greater the compression ratio, the greater the working pressure.

We know that the mixture will generate heat during compression. The greater the pressure in the cylinder, the higher the heat and the higher the temperature. In order to prevent the engine from deflagrating when the mixture is not ignited, the gasoline matching the label should be selected according to the in-cylinder pressure. It is suggested to add 92# and use gasoline engine 95#. No problem. Some people think it's okay. No.95 gasoline burns slowly. At low speed and low load, gasoline cannot be completely burned in the combustion chamber, and the power will become worse.