Well, like toysrme said, it depends on a lot of things. It's not a very reliable variable for precise calculations. Throttle position, how clean the engine is, air filter, valve lash, cam, muffler, and on and on. Change one little thing and there goes your VE number and your calculations. Heck, it won't even keep the same VE across the rpm range. You can figure max VE at max torque rpm, but that's your only constant.
What are you trying to calculate?
Yep, that is right. Regarding the mods. As I'm going along and the mods will help my engine. I just want to keep track of everything to see which works. ADN alzo which might be detrimental to the engine.
Well that's a good idea, but the VE has to be measured, not calculated. Even then, it's not a guarantee if there is a lot of overscavenging of the exhaust happening. It is sometimes estimated based on HP, RPM and engine size with some guestimated constants thrown in to account for frictional losses in the valve train and pistons, combustion efficiency, etc. Most of the time it is measured on the dyno with a Dwyer tube or the like. Which brings me to an idea for you.
Since the car is a 97 and OBD2, you can get a scanner set up that reads the cars sensors in real time. One of those sensors is the AFM. You can make notes of the reading at specific rpms at WOT and compare them to what you get after mods. Some scanner software can data log and that makes it easier. If you take in more air, you can usually assume you are improving your VE and your power(with some concerns for fuel and timing, etc). Beware, overscavenging the exhaust can cause an increase in airflow through the intake with a LOSS of power. This is because fresh charge is drawn out the exhaust during overlap effectively lowering the amount that is in the combustion chamber.