[s-cars] 1.9 Bar Wastegate Spring

[cody at 5000tq.com]

Quoting Mark Strangways <StrangConst at rogers.com>:


>
> A higher spring rate will solve some WG creep issues as will cranking the
> spring seat down.


Ah, but to make sure we keep things clear here you should be aware  
that he is not talking about wastegate creep. Wastegate creep is when  
your wastegate doesn't flow enough and your boost creeps up higher and  
higher past the desired level at high RPM.

What you meant has no "name" that I have ever heard, but is caused by  
small ammounts of pressure ever so slightly cracking the wastegate  
open before the desired boost level is obtained, thereby deverting  
gases that we would prefer to be putting effort towards spooling the  
turbo. Higher spring tension compensates and fixes the problem, or a  
simple pressure relief valve in the lower wastegate chamber pressure  
line set just below your desired boost level works better.

The best part about using the relief valve is you can put it in the  
car somewhere and actually adjust how fast the turbo spools - usefull  
for the track so you can let it spool slower to help prevent breaking  
the tieres loose near the exit of a corner. That and you can also use  
the relief valve to get some mid-range power. It opens at X pressure,  
and doesn't close until about 10psi lower then X pressure. That way  
you can get an extra 2 or 3 PSI, then it opens and lets the WGFV do  
it's job.

I use a pressure relief valve as the sole boost control on my 5ktq.  
The valve I use can be had from any supplier or Norgren pneumatic  
supplies for $18. Let me know if you need a part number.

-Cody Forbes
http://www.5000tq.com