[HawgRyder]

I think what is missing is the idea that air/fuel mix is a FLUID!!
Fluids have mass.
Once a mass is in motion it tends to stay in motion unless acted upon by an outside force.
So...at higher RPMs...the slug of fuel/air is travelling down the intake tube (Lotus...way back in the 50s figured it out to be something like 300 feet per second) and until the intake valve closes...that slug will continue to travel down the tube.
When the intake valve finally closes...it does so with some effects.
Think of when you quickly shut off the tap in the kitchen...and you hear the "bang" from the pipes...this is the mass being stopped by the valve.
So even though the piston is rising (compression cycle) the slug of air/fuel has enough inertia to overcome the pressure being built in the chamber for a short time.
The timing and overlap of the cam now come into play.
Really high performance engines have both the intake AND exhaust open at the same time (overlap) so the incoming charge will assist the purging of the cylinder of old burnt gasses.
The timing (overall) is what you are concerned about...welcome to the engineering part of cars.
In an ideal world...we would be able to change the timing of all the parameters to get the most power/fuel economy/torque out of the engine...we can...now the technology exists to do all of that...its called electronic control of valve movement!
Some race engines have no camshafts at all!
They use coils to open/close the valves!
This allows ALL the parameters to appear at your fingertips (on the computer).
Now...only your brain is the limiting factor.
Have fun.
Bob