Originally Posted by INTMD8
My question is, why is that pressure only on the back side of the intake valve?

If you have say 15psi, it's filling the cylinder through the entire intake stroke and as the piston is coming up from bottom dead center chasing the intake valve closed, would it not be fair to say that boost pressure and pressure in the cylinder has equalized (or close) at that point?

Then as soon as the intake valve touches down you're on the compression stroke, far exceeding any boost pressure.




I see your point, but in my limited experience with boosted engines the manifold pressure seems to be more or less constant but dependent upon RPM. I don't know but I'm going to guess that the cylinder fill vacuum is greater than typical boost pressures seen on gasoline engines.
Again, I must reiterate, it's just conjecture here, anyone know for sure ??

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