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Originally Posted by Multiades
That's probably about 1.4sq in of flapper area * 30psi = 42lb on the actuator rod. The diaphragm opens when you put maybe 7psi on it. The area of the diaphragm is about 2.25", or about 4 sq in. If the spring opens at 7psi, that's about 28# (7*4) that the diaphragm must exert against the spring to open. Soooo 42lb is very likely to push it open.
The above example is with his Bullseye 38mm wastegate flappers (which might have 34mm of exposed diameter). Stock TD05 flappers have about 0.8 square inches of area, while mine (34mm TRE) probably have closer to 1.1 sq in. These cases would yield 24# and 33# respectiveliy on the arm at 30psi across the turbine.
Sounds to me like a good case for upgraded wastegate actuators with STOCK TD05 flappers!
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I know that TEC has dual port wastegate actuators. one nipple is used to hold it shut with boost before desired boost is reached, then the boost controller flips the ports so that port is no longer pressurized and pressurizes the other port which pushes the valve open. I do not know who makes them, and I've only had the pleasure of seeing them once, on a local 15G car. Currently TEC is closed for business for a death in the family, when they reopen you had better beleive I'll be in there getting some for my TD05's.
As for pushing the valve open prematurely, ABSOLUTELY! I've seen it myself while somebody else revved the engine at WOT to redline. Keeping it shut tightly could do wonders for reducing lag
