TF & Speedmaster Flow Tests

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?