When the gasoline vehicle fails to pass the environmental protection test, we often hear a suggestion that is: "add some high-grade gasoline to the car, the high-grade oil quality is better, the combustion is more sufficient, so the emission will be lower." It is certain that high-grade gasoline is more expensive, but is it really effective in reducing emissions?
Let's first understand the concept of gasoline label. The most common gasoline in China's market is 92 and 95 gasoline. The biggest difference between 92 gasoline and 95 gasoline is that the proportion of n-heptane and isooctane is different: 92 gasoline is rich in 92% isooctane and 8% n-heptane; and 95 gasoline is rich in 95% isooctane and 5% n-heptane. The difference in the proportion of n-heptane and isooctane in two kinds of gasoline directly leads to the different antiknock properties of the two kinds of gasoline. In fact, the gasoline label represents the antiknock property. The larger the label, the better the antiknock ability (because it contains more octane). This has nothing to do with the quality of the gasoline itself. It does not mean that the higher the label, the less impurities there will be.
The higher the gasoline grade, the better the antiknock performance. But what does antiknock represent?
When the oil-gas mixture is injected into the cylinder, the piston moves upward to compress the oil-gas mixture. When the pressure increases, the temperature rises. If the antiknock property of gasoline is too low, it will start to burn before the spark plug ignites, thus forming deflagration, which is commonly known as knock. Detonation not only affects the output of the engine, but also causes damage to the engine.
In fact, there is a term called "compression ratio" in the manual of each car. Generally speaking, if the engine with high compression ratio uses low-grade gasoline, it will make the gasoline combustion incomplete, the machine will vibrate strongly, so that the output power will be reduced, the parts will be damaged, the fuel consumption and driving will be weak. However, if the engine with low compression ratio uses high-grade oil, the phenomenon of "delayed combustion" will appear, that is, when the compression ratio reaches the highest point, the combustion will be incomplete and the emission of pollutants will not be reduced. Generally, 90-93 vehicle gasoline should be selected when compression ratio is 8.0-8.5; 93-95 vehicle gasoline should be selected when compression ratio is 8.5-9.5; 95-97 vehicle gasoline should be selected when compression ratio is 9.5-10. However, it is not suitable to select the gasoline grade according to the compression ratio on some engines with lean fuel technology and turbocharging.
Therefore, it is still necessary to add the corresponding brand of fuel to your car according to the recommended value given by the automobile manufacturer. Blind oil replacement not only has no greater help to the emission of pollutants, but also causes damage to vehicles.
If the emission of gasoline vehicle is not up to the standard, it is necessary to check the driving control computer, intake system, engine carbon deposition, three-way catalytic device, oxygen sensor and so on, so as to make the engine in the best working state, so as to reduce the emission of pollutants.