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Old 08-06-2006   #11
Shane@DBPerformance
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Join Date: Oct 2003
Location: On the dyno
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Re: Bigger and better

The problems you might run into with an internally gated setup are:

Having trouble running low boost(creep)

Maintaining very high boost levels(boost drop in the upper rpms), high backpressure can hold the flapper open, the bigger/more surface area of the flapper, the more likely it is to have trouble at high boost. Externals can have this problem too, but there are often many higher pressure springs to choose from with an external and you can push boost to the top port of an external to help hold the valve shut.

Unstable boost(boost level wavering up and down a couple psi), I mostly see this on the ball-bearing GT28 sized turbos

Slightly more lag than an external(externals don't usually start to open until immediately before full boost, internal flappers are often partially open much earlier)
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