TF & Speedmaster Flow Tests

PRH said
My suspicion is, especially when working with a low port head that doesn’t have a lot of height at the SSR, that even ports that seem to have a form that allows the flow to stay connected to the floor(no real obvious change in sound, and flows not backing up), that they still end up having areas of the valve perimeter that “go dead” at a certain lift.

But, you have to get a port form that “seems” to be good first(like one of PBR’s non-stalling ports)………then the seat velocity test would tell the tale.

With your current heads, at what lift do you see the dead areas start to show up?

This attachment might be hard to see. All is good at 0.200, there are signs at 0.300, the first zero shows up at 0.400.

Across the top of the second attachment are the corresponding port velocities at the apex for the different valve lifts. The second attachment shows the port and chamber looking down from above, so the 3 oclock and 9 oclock positions are opposite of the drawings in the earlier posts.