What Does the Octane Rating of Gasoline Mean?

1 Answers
NadiaLee
07/30/25 1:59am
Gasoline octane rating: It is the ratio of the actual anti-knock performance of gasoline to that of standard gasoline. The higher the octane rating, the stronger the anti-knock performance. Standard gasoline is composed of isooctane and n-heptane. A higher octane rating is not necessarily better; it should be reasonably selected based on the engine's compression ratio. Criteria for selecting gasoline octane rating: The primary criterion for choosing the gasoline octane rating for a car is the engine's compression ratio, which is also a core energy-saving indicator of modern cars. The operation of an engine consists of a cyclical motion of "intake--compression--combustion--exhaust--intake" in the cylinders. The compression ratio is the ratio of the cylinder volume when the piston is at the farthest and nearest points in its stroke. The most cost-effective method to reduce fuel consumption is to increase the engine's compression ratio. Increasing the compression ratio merely changes the piston stroke; the more the air-fuel mixture is compressed, the greater the combustion reaction and the more complete the combustion. However, the compression ratio cannot be easily altered because it must be matched with another indicator, namely the gasoline's anti-knock performance, also known as the octane rating. Gasoline anti-knock performance: The octane rating of gasoline determines the timing of the knock point, which essentially determines the engine's power output. The anti-knock performance of fuel varies with its composition. The higher the fuel's anti-knock performance, the higher the engine's compression ratio can be, improving both the engine's fuel efficiency and power performance.
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