Enlarging PRP doesn't always help

With certain heads, I often say “it’s all about the SSR”.
Really……..but also not really.

Imagine messing with a SB J head, T/A version.
Someone does half assed bowl job that leaves the SSR shaped like an abrupt cliff and it flows like [email protected]” lift, and the flow starts to drop of after that.
These heads have lots of material to play with at the PRP.
You can easily widen the port in that area by .125”+.
It won’t improve the flow at all, because the poorly shaped SSR is still just as bad as it was.
However, If you left the PRP alone and put a decent radius on the SSR and laid it back a little, there would be a pretty easy 10cfm gain.

Conversely, I have also see it where the SSR is working well, and the flow numbers are good, and the drop off at high flow is minimal.
Then you go in and open the pinch up “more”, and all of a sudden the peak flow is less, and the upper end of the curve falls of worse.
My take on that is the SSR can no longer manage the volume of air trying to get around the turn, even if it’s only in specific areas of the turn.

I’ll reference PBR’s tests on the TF190’s where he’s found inconsistencies from port to port, and he’s mentioned remedying some of that away with some minor tweaking.
Is that tweaking happening at the pinch, or the SSR?
I’m going to guess it’s the SSR, but I’m sure he’ll chime in.

I guess what I’m saying is, if the SSR doesn’t have the proper form to allow the flow column to stay attached, you can’t fix it by reworking other areas of the port.

The trick is…….knowing when the separation is caused by the shape of the floor, or by deficiencies in other areas of the port…….or both.