Question for the head porting experts.

Cuda416 said

Yes it's a very general question as it's meant to be. I am trying to get a handle on the basic theory of things before getting into specifics. Your answer helps so thank you for that.

I understand the CSA from valve to gasket is going to change and the specific delta is important but different in all cases.

My question is maybe better stated in asking specifically should the delta/taper "cone" shaped or "trumpet" shaped if that makes sense

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I think the trumpet shape your referring to is for the first piece in the system on the end that sees the air first. The entrance. Like a velocity stack on fuel injection. The bell on the end is to provide a radiused inlet as opposed to a sharp edge inlet which creates turbulence. Air likes the radius better. This is why a radiused inlet or clay in the same radiused shape is put at the inlet end of the port on a head that is being flowed on a flowbench. If the intake manifold is attached then obviously the radiused inlet is not needed at the head port inlet.