Compression ratio

Compression ratio is like squeezing a sponge. When you squeeze the sponge, it gets smaller and the water inside is compressed.

Similarly, in an engine, when the piston goes up inside a cylinder, it compresses the air and fuel mixture that's in there. This makes the mixture smaller and more powerful, like the squeezed sponge.

The compression ratio is a comparison between the amount of space in the cylinder when the piston is all the way up to the amount of space when the piston is all the way down. This tells you how much the mixture is being compressed.

For example, if the cylinder has a volume of 10 cubic inches when the piston is all the way up, and a volume of 2 cubic inches when the piston is all the way down, the compression ratio is 5:1 (10 / 2). This means that the air and fuel mixture is compressed 5 times its original size, making it more powerful.

But if the compression ratio is too high, it can cause problems like engine knock or detonation. This is like if you squeezed the sponge too hard and it started breaking apart. So, a balance must be found between the benefit of a higher compression ratio and the risk of damage.