Question on port matching

12many said
What I’m understanding is:

Intake port window smaller than the head? No

Intake port window matched to the head? Yes. The goal.

Intake port window bigger than the head? Yes, Acceptable, Better than smaller

That’s the conclusion I come to with what RB is stating.

We all? agree Matched is the goal.

But, I always thought (from reading various articles and books over the decades) a smaller intake port window would be better than a larger port window as they meet the heads.

Has anyone tested this or know of others, have links to articles that have? (not the matching of intake/head but the larger vs smaller intake to head?)

Exactly correct. Why some are struggling with what I wrote stumps me. You never leave the intake smaller than the head. If you are going to the bother of port matching, make them the same. And if core shift or something makes it not possible to line everything up then make the manifold bigger.

All this talk of reversion, wet flow and all that is just that. The science says a step on the backside of the direction of flow will cause vortices and that is a flow killer and a power killer. If the step is in the direction of the flow, it will shear off and not develop vortices.

Think about it this way. Look at the dividers in the plenum of the manifold. The air shears off of them and finds its own way without developing vortices. And, there are times when you make the dividers sharp. As long as that edge is in the direction of flow it won’t care.

Edit: I forgot to mention how simple this is to test on a flow bench. And that is testing with relatively dry air. You need 3 different sized radius plates. Start with the correct size and make a test. Then put a radius plate on the port that is bigger than the port and see what you get. And then use a plate that is smaller than the port and see what happens.

The correct sized plate and the bigger plate will flow the same. The smaller plate will kill flow. And the port will get very noisy. Pretty simple test.