Well, lets start with the basics.
How does a carburetor work?
Suck, squeeze, bang, blow.
The engine sucks in a mixture of fuel and air, then squeezes it together (compresses it), then it burns / explodes that with a bang, and finally it blows out the exhaust
If an engine has a high compression ratio, it means that a given volume of air and fuel in the cylinder is being squeezed into a much smaller space than an engine with a lower compression ratio.
Pretend you have an engine whose cylinder and combustion chamber volume is 10 cc when the piston is at bottom dead center.
What Defines Compression Ratio Is Super Simple
A compression ratio is exactly what it sounds like—a ratio where you’re compressing the maximum cylinder volume into the minimum cylinder volume. That’s the volume of the cylinder when a piston is all the way down compared to all the way up to the top. It’s written out and said as a ratio. For example, for an engine with a 9:1 compression ratio, you’d say that it’s “nine to one.”
Now picture a cylinder in your head. The piston moves up and down inside that cylinder. When the piston is at the lowest point, that’s called Bottom Dead Center. That’s where the cylinder volume is greatest. When the piston is at the highest point within the cylinder, that’s called Top Dead Center, and that’s where cylinder volume is smallest. The comparison of these two volumes is where your ratio comes from.
If you are a visual learner like I am, you’ll like this GIF I made showing how a four-stroke engine works. See how the piston moves up during that compression stroke? That’s all the air and fuel getting compressed in the cylinder. If an engine has a high compression ratio, it means that a given volume of air and fuel in the cylinder is being squeezed into a much smaller space than an engine with a lower compression ratio.
I recommend:
I use it in a 1968 Corvette with an L88
Another option, though not as well tested.