Originally Posted by rxspeed7
I'm just going off what we have seen with all of our race cars and manifolds we have built. Everytime we have tried to have "good" wastegate placement we have had horrible boost control after 30psi.
After having this problem more than a few times we started logging emap to see what was going on and decided to start building the wastegate runners as close to the turbo as possible because that's were we saw the highest emap. After doing this haven't had a single issue.
Not trying to stir **** up but I speak from experience not Internet readings or theories. May sound good on paper but don't always work as good as they sound.
No one is denying your experience but it seems that you have certain misunderstanding in what you have experienced.
You can't have pressure drop without flow drop or temperature drop and unless the wastegate is some extremely efficient cooling device that would control manifold pressure via temperature it is what it is - flow device.
Reason why you experienced best boost control in the place where is highest EMAP could be pretty simple, highest pressure delta, best flow towards the wastegate.
There are too many variables, wastegate is venting up to 50% of total mass flow through the system in some applications, and exhaust gasses, despite under pressure, have its own inertia and they don't like to change direction.
It seems that it goes down to application, for example Turbo F1's had wastegate runners at right angle from the collector, on the other hand some low boost race cars have manifold design which prefers wastegate flow.