[Steve C.]

Regarding his point stating there is not really much gain when a port is maxed out in cfm air flow no matter how far you continue to open the valve it cannot flow any more air.

Regarding that, if interested there is this tid bit to explore that is published by David Vizard:

VALVE LIFT.
"A 2-valve cylinder head typically continues to flow more air up to lift values equal to as much as 0.35-0.4 times the valve diameter. The reason for this is that there is a flow pattern transition period that takes place at a lift value of about 0.25 of the valve's diameter. When this point is passed, if the port has been modified to support flow in this lift region, the valve efficiency actually starts to increase. This is the reason why a 2-valve engine responds to high lift."
"If you want to build a street motor with the most power without a sacrifice of idle and low speed qualities, then lift is the most important factor to maximize, not duration. The best street cams are those that seek to maximize lift while only adding a minimal amount of duration."

And another tid bit to explore, in part from the video....

"... the crank shaft has to overcome the resistance that the cam is putting on it so in other words the cam is a parasitic draw it takes horsepower to actuate the cams it also takes horsepower to compress these springs..."

Does this info below relate ?

Common Misconception:
Many people mistakenly think that using higher seat pressures causes a reduction in the horsepower delivered to the flywheel because higher seat pressures (and also higher spring rates required for high performance) require horsepower to compress the springs. This thinking is simply incomplete! For every valve that is opening and its valve spring being compressed, another valve is closing and its valve spring is expanding. This expansion returns the energy to the valve train and the engine. This results in a net power loss of "0" hp. Many engineering texts refer to this as the "regenerative characteristic" of the valve train. Recent tests at Crane have shown no horsepower loss on a hydraulic roller equipped engine when changing the seat pressure from 135# to 165#. Power actually improved significantly at top end, probably due to better control of the relatively heavy valves in the engine.
Source: Crane Cams


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