TOPIC:

Yea, guys. It's me again.
I have two questions.
#1. Can someone explain to me just what a flow bench is, how it works, and how to fabricate one?
#2. How is compression ratio figured? How does one determine just what "ratio"? his engine is running/producing?
Thanks,
Jim

Why don't you ask easy questions, sheesh!

A Google search for flowbench would be better, there are plans out there. They are used to compare airflow on a before and after porting basis, don't ever try and compare a head tested on one flowbench against a head tested on another flowbench.

Compression ratio is a ratio of the displacement vs remaining volume. If a cylinder displaces 250 cc and the remaining volume is 25 cc, then that cylinder has a "Static" compression ratio of 10:1.

You can place the piston at BDC, measure the amount of fluid it takes to fill the cylinder, then raise the piston to TDC and measure the amount of fluid that is displaced. That will tell you the displacement of the cylinder and the compression volume (the amount of fluid left in the cylinder).

I'm pretty sure there will be some discussion about this

Compression Ratio, as Steell said, is the Ratio of the volume contained above the piston at BDC v/s the volume contained above the piston at TDC.

So, Bore divided by 2, squared, times PI, times the stroke PLUS the volume of the combustion chamber in the head, less the volume of the crown of the piston V/S the volume of the combustion chamber in the head less the volume of the crown of the piston.

If calculation #1 produces 253 cubic cm and #2 produces 25 cubic cm, your compression ratio would be 10:1 (approx).