Point is, when the intake valve opens it's not like someones hand comes down and is just pushing on the backside of the valve, the pressure at the valve is moving to the cylinder, equalizing pressure.

So if manifold pressure is a steady 15psi, go through the motions.

Intake valve opens, intake charge flows into cylinder and pressure starts equalizing behind the valve and after the valve (in the cylinder).

I would think it has near/same as manifold pressure in the cylinder at intake valve close at which point compression takes over and cylinder pressure multiples higher than boost pressure.

Plug fires, power, again, much higher pressure in cylinder than back of the valve.

Exhaust, ok, we will reach a point now where boost pressure will exceed cylinder pressure after blowdown but the valve has been closed for long enough now it certainly isn't getting blown open by whatever boost pressure is.

Now we start over at intake valve opens.

At no point in time do I see where boost pressure acting on the back of the valve isn't the same or higher on the combustion chamber side of the valve, at any point in time it would matter.


I'm not a fan of light spring pressure myself and would rather have some overhead boosted or not. I just don't subscribe to the theory of add X amount of psi for boost pressure acting on the area of the valve at seating surface minus valve stem for reasons stated above.