2006 Noble M400 #141

[asshanson]

Yea, the Borgs come by default with the "medium pressure" wastegate actuator. Spring without preload is around the 10psi range, and adding preload can set tension anywhere between 10-17psi before it opens. For you crazy DSM/Evo guys on race gas, that's not enough to run 30psi on an internal gate, so they make a "high pressure" actuator that will open between 17-25psi just on wastegate pressure alone, depending on preload.

Obviously a boost controller can prevent the flapper opening until higher boost amounts, but you don't want a 10psi spring if you're running 30psi because exhaust pressure will force the flapper early, this just results in lower boost than desired.

However, this is not my problem, as I only want to run 15-17psi for the time being. And I have 0 psi.
I still have not had time to take the downpipes off, work is killing me. It's 3am and still at the office. Hopefully by Friday evening I will have time to visually inspect the flappers and turbine wheels..

EDIT: Spaz, these were some of the first BW EFR turbos, so it's definitely possible that it's a metallurgical issue with the arm to the flapper bending and now it's always open. Either that or the turbine wheel was taken out by a piece of exhaust manifold breaking off. Those are my two best guesses right now, will find out soon. The noble/rossion manifolds are notorious for taking out turbos.