Quote:
Originally posted by JET@Oct 23 2003, 08:06 PM
You don't actually need to put on a bigger flapper if you port it correctly. Running a bigger flapped means that you cannot run as high of boost. I had my 16g ported so that there was no creep with a 3" turbo back exhaust. The big trick is where to do the porting at.
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While this is true in part in certain instances, it is not true across the board. Contouring the wastegate entry can help in some cases, but not all. The wastegate hole diameter becomes a bottle neck in many systems with increased exhaust flow. You can make the entry into the wastegate as free and easy a transition as can be, if the wastegate itself is too small it is still a restriction and will still cause boost creep. Larger flappers have been a consitant and proven method of controlling boost creep for many years and not without reason. As far as not being able to run higher boost, depends on the porting going into the flapper area and the diameter of the hole, it can be made too large for the diameter of the flapper and hense cause blow open at higher boost levels. The entry into the wastegate can be over-ported and also cause an issue with premature opening of the flapper, as well as causing an unnecesary turbulant path to the exhaust wheel itself. For a 34MM flapper, a wastegate hole of 28-29MM and a properly ported housing will most of the time control boost creep without causing issue with blow open or negative effects on flow to the exhaust wheel.
Personally I would only run an internal gate on smaller turbos (up to a 20G). They may work for larger turbos, but IMO, if you are going for that kind of performance, why settle for an internal gate.