My mates car got a problem with the boost.

Running on wastegate spring pressure, the car dont stop boosting.

First we used his wastegate with a 0,6bar spring.
Had the car on the dyno, and the car boosted over 1 bar @ 4000 rpm.

We thought that maybe the wastegate was broken, so we took my wastegate, and put it on his car, same problem.

What could be the problem.

Both wastegate was Tial V44.

we were running without the boost controller connected under the test, and only a hose from turbo to side port of wastegate.

 

Did this just start happening or has it always been like this? What size exhaust does it have and what series is it s4/s5?

 

what turbo manifold are you using?

 

The problem has always been there, and i was told the previous owner of the turbo and manifoil also had that problem.

This manifold was made for a FD, but we have used it on a S5.
The turbo is a GT35R and has been rebuilt in the UK 2 months ago.


Got som pictures of the manifold....

 

The issue is due to the poor runner placement on that manifold. I'm not sure it could actually be worse.

 

yeah that wastegate runner looks about the absolute worst for flow.