Has the intake charge stopped moving and is now being pushed back out of the cylinder via the intake port (reversion) before the valve is closed? Or are we trying to time it to prevent that? How much of the intake charge has escaped out the exhaust during overlap? What about using the timing of events and head design to "supercharge" a NA engine beyond 100% VE? Wouldn't/doesn't measuring the volume of air entering the engine vs the displacement x number of RPMs over a period of time give you some type of calculation?

Engine RPM and atmospheric pressure have to play a part in this.

This stuff fascinates me and I wish I had gotten involved in the physics of it when I was younger. Nowadays I just deal with what is happening behind the flywheel.

People who get it, Pro Stock and high end NA engine builders and tuners, get all my props.