stock turbo + MBC = boost taper theory

[EnjoyDriving]

Interesting topic, and how many people are seeing successful results from using the aftermarket WGA??

[Kracka]

Depends what you mean by successful. They will hold boost better in the upper RPM's, but you'll generally also see a larger boost spike depending it it's rated pressure. I'm thinking a 17psi one would be fairly effective for guys running 25+ but we'll really have to wait for someone with experience with one to chime in.

[CarPsyco84]

Internal gates are pretty well known to get blown open at higher rpms because the exhaust pressure pre-turbo is higher from the higher airflow through the engine. I used a hardware store spring on my wastegate back in the day, and It ran around 17psi with no boost controller and it seemed to hold the boost more stable than without it. Without the helper spring it would spike 2-3psi higher and then fall back.

[Shane@DBPerformance]

Food for thought:

A turbo can only flow so much air. When you hit that limit the boost will drop as you go up in RPMs.

Boost is a measure of restriction. You make things flow better and you make more power with less boost, because there is less restriction.

Sometimes trying to force more boost up top results in less power or a lot more knock due to excessive back pressure in the exhaust housing from overrunning the turbo like crazy. One of the jobs of the WG flapper is to open when exhaust back pressure gets too high.

[badinblack]

Another idea is a hole drilled at an angle so it would have a progressive port like a 2 stroke port?

[EnjoyDriving]

I'm not sure if the "tightening arm" will help the tapering "issue". In my thinking, the shortening is to reduce the amount of "opening" on the flapper and also make it shut tighter and faster, therefore improving the spooling?? But on the other hand, won't it make the wastegate easier to crack open by preloading it??

With a stiffer spring, like getting a Forge WGA, it would definitely hold the boost better, but won't it be more prone to the "boost spike" problem?

Please chime in on "tightening arm" vs "stiffer spring"