Originally posted by turbotalon95
Not a problem. This usually affects stock turbo cars and cars with custom turbokits that have internal wastegates and large unrestrictive exhausts. Basically the problem comes with the fact that the exhaust outflows the wastegate. The wastegate cannot divert enough exhaust gasses to limit boost properly. In the end you get inconsistent boost pressures or even uncontrollable amounts of boost. This is called boost creep and what happens is that you set you boost to the desired amount, but as you accelerate hard the boost will hover at what you set it too for a second then in higher rpms it begins to rise uncontrollably. I had a problem with this before I upgraded my wastegate, I would set it at 15 psi and at redline I would actually be in the 23-24 psi range. There are certain things that you can do to help with boostcreep, but the best of course is an external wastegate.
boost creep comes from a well flowing exhaust and turbo that can move lots of air with a restrictive o2 sensor housing. if the wastegate cant let enough air out of it (as is the case with a stock or unported wastegate/o2 sensor housing on a hybrid turbo, etc then the air it cant let out has to go somewhere and ends up going through the turbine creating more boost.....not the fact that the exhaust is too large. what you needed to do in that situation is upgrade your o2 sensor housing to a larger one or just porting it out. i know this can happen on 14b's with bolt on 1g's, and is remedied by porting the stock o2 housing and taking some material out from behind the wastegate flapper arm...