What is the compression pressure of a gasoline engine?
2 Answers
The compression pressure of a gasoline engine is between 9 and 12 bar. Typically, engines with low compression ratios are below 10 bar, while those with high compression ratios exceed 10 bar. Older gasoline engines have compression pressures ranging from 6 to 10 bar. The compression ratio of a gasoline engine refers to the degree to which the engine's air-fuel mixture is compressed, which is the ratio of the total cylinder volume before compression to the cylinder volume after compression. The volume formed by the engine piston moving from the lowest position to the highest position represents the smallest volume during the entire piston stroke. The compression ratio to be calculated is the ratio of the maximum stroke volume to the minimum volume.
I think the compression pressure of a gasoline engine is a pretty critical indicator, usually ranging between 120 and 180 pounds per square inch, but this depends on the engine's specific design and condition. For example, a naturally aspirated engine with a compression ratio of 10:1 would have a pressure around 130 psi; if the compression ratio reaches 12:1, like in some high-performance cars, the compression pressure would be higher, possibly up to 200 psi. Low compression pressure is not a good sign—it could indicate worn piston rings or poor valve sealing, leading to cylinder leakage, reduced engine power, and increased fuel consumption. Personally, I make it a habit to use a simple pressure gauge for a quick check during maintenance. If it's below 100 psi, it's time for immediate inspection. Regular checks like this can prevent major overhauls and keep the engine running efficiently, which is especially important when driving older vehicles.
