Absolute Shower

Being a plank when it comes to turbo's, what difference would a different size restrictor make in the pipe from turbo to wastegate? Is it larger restrictor (less flow), gives more boost control for the ECU, but less spool up and smaller (more flow), less control, more spool, but less top end?

I'm also trying to understand how the dawes works, say for a low setting which restricts flow for about 5 psi.

Pete Croney

AS

The restrictor is there to stop the wastegate acting as the boost rises. Consider it a delaying device in the boost control. The smaller the hole, the slower the wastegate gets to see the high pressure and the less it can do about it. The bigger the hole, the quicker it will react and the greater force it will have to react with.

Small = hole lots of boost with little control.

Big hole = low boost, lots of control.

On an STi 7/8, the hole was deliberately very small, to try and get some action out of the turbo. When decatting these cars, the boost spiked massively before the wastegate could react, so a bigger restrictor was needed. The held boost pressure is the same, but the spikes could be arrested before they started. When we remap these, we rewrite the wastegate duty tables and boost profiles, so that there aren't any spikes with a decat and the standard restrictor.

alexWRX

i aint got restrictor to wastegate at all. Put a straight hose from solenoid to wastegate. No pbrolems so far.

Delboy2

Alex - you're using a greddy boost controller though instead of the standard control.

alexWRX

But i got boost controller.

Should restrictor be remained in system if boost controller being installed.

Delboy2

Shouldn't do, I haven't got the restrictor in mine since I installed the HKS boost controller and mine controls perfectly

alexWRX

cheers. mine as well.

Absolute Shower

Cheers for the reply Pete - makes sense now.