Low and Fluctuating Boost Problem
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From: CA, Rowland Hts.
so... its the wastegate! Basically had a straight rod going to the flapper to keep it somewhat closed and boost went up dramatically.
Now I need to decide if I should obtain a new 'larger diaphragm' actuator, or an actuator with a stiffer spring, or shorten the rod to close off more of the wastegate.
Now I need to decide if I should obtain a new 'larger diaphragm' actuator, or an actuator with a stiffer spring, or shorten the rod to close off more of the wastegate.
i would answer your question but i know nothing about boost yet 
Just use the same actuator that I do and be done with it (some fabrication required).
If his WG actuator is blowing open that badly, no amount of pre-tension is going to fix it, not to mention the issues that result from restricting the full-open position of the flap.
Just use the same actuator that I do and be done with it (some fabrication required).
Just use the same actuator that I do and be done with it (some fabrication required).
Not that this has anything to do with anything... but I saw this and it looks cool! It would be nice to run stainless v band.
http://www.atpturbo.com/root/releases/release103105.htm
I want one........
http://www.atpturbo.com/root/releases/release103105.htm
I want one........
But - if you adjust your arm carefully you can actually dial in what ever maf you want , leaving a little spare for safety .
When you think about how boost control works you realise there is nothing wrong with this solution .
Your larger actuator is probably more of a pain because you probably have very little adjustment at lower rpm IE you cant go BELOW 10psi .....
Having taken the turbo out about 6 times a year.... sometimes you just feel lazy and wanna pop it off.
what does any boost control method do ? It holds the wastegate flapper in a certain position to restrict flow .......
how it does it is not that important - the fact that a certain position yields a certain boost (or maf) ............IS
Because preload on the diaphragm spring does NOT do the same thing as properly controlling the wastegate diaphragm lever arm.
What you are doing is simply shortening the opening angle and cracking point for the actuator. You are NOT addressing the hold pressure or opening rate, which are responsible for boost response.
You may very well have accidentally come across a method that doesn't cause all kinds of wild boost level issues on your particular setup, but you are opening yourself (and anyone else that tries this) up for all kinds of crazy - and potentially damaging - boost response issues.
BTW - This all works as a perfectly demonstrative example of the boost/flow misunderstanding since it is essentially the same problem, only the lever medium is different.
What you are doing is simply shortening the opening angle and cracking point for the actuator. You are NOT addressing the hold pressure or opening rate, which are responsible for boost response.
You may very well have accidentally come across a method that doesn't cause all kinds of wild boost level issues on your particular setup, but you are opening yourself (and anyone else that tries this) up for all kinds of crazy - and potentially damaging - boost response issues.
BTW - This all works as a perfectly demonstrative example of the boost/flow misunderstanding since it is essentially the same problem, only the lever medium is different.
anyway we have argued this to death before and you are better at arguing than I am even when you are wrong so all i have to say is :
bollocks
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From: CA, Rowland Hts.
/\ sounds like it . Pity you didn't make it adjustable and gradually bring it in ...... would like to see if other setups also respond well to this
Last edited by Brettus; Feb 1, 2010 at 05:43 PM.