[Eagledriver]

I think there is no reason to use ITB's on a Turbo. Here are some reasons:

1. In a turbo you control the amount of air going into the cylinder by the amount of boost you run. If you have a more restrictive throttle set up you can run more boost. Any pressure drop accross a throttle plate will cool the charge so the there is no down side to raising the boost to compensate for a pressure loss.

2. As far as velocity at the throttle plate, this has no meaning IMO. The velocity at the inlet port at WOT is the only thing that counts. Part throttle power settings are determined by the throttle plate opening. Who cares how much flow you get at part throttle...if it's not enough you open the throttle more.

To summarize: ITB's are great in NA engines because they maximize the pressure available at the intake port at WOT. In a turbo you can set the pressure so you don't care about a small loss in the system. You set the boost to get the power you want (respecting the maximum pressure the engine can handle). If there is a loss in the intake system then you will have a cooling effect due to that loss and can run higher boost to compensate with no danger. (These are small changes we are talking about).

-Andy