Good stuff! So in layman's terms, the more efficient the fuel/air mixture can be introduced into the combustion chamber, and then compressed before the spark is introduced, the better.
Gasket matching, porting, bigger intake valves, smaller combustion chambers, longer duration on cam lobe.
Basically allowing the air pump to flow as much air as possible in the most efficient manner? Does that explain VE in simple terms?
Indeed there are a lot of variables, but to panic's point let's not cloud the concept. VE is simply how much of the displaced cylinder volume is actually being put to work.
Let's look at two examples from 70 years ago. Check out the specs for the '49 Pontiac
Chieftan 6. The engine displaces a little over 239 cubes. Now compare that to the specs for the '49 Chevrolet
Special 6. The Chevy engine is over 22 cubic inches smaller. Yet both produced ~90HP at roughly the same RPM.
Why?
The 216 Chevy has a much higher VE then the 239 Pontiac.
Why?
Valve in Head versus Valve in Block:
The overhead valve configuration flows better. Given a flat-head design the Pontiac engineers had to employ more displacement in order to produce the target 90HP driving experience for their customers.
As a tuner one needs to take the displacement at hand and make the most of it.
