exhaust pressure forcing opening waste gate stock actuator

[dyermullet]

Has any experienced this issue.  I have been experimenting with a new setup and using a grainger valve (manual boost controller) I built.    I have the factory waste gate with the typical cut and threaded rod.  When I installed the manual boost controller I also loosened the tension on the waste gate rod.  I set it to where i only need to tension the spring the diameter of the hole to hook the rod onto the flapper arm.  I can't get higher than ~20 psi even when I bottom out my manual boost controller.  I was able to make adjustments and get a response until I got up near 20 psi then no more. 

I am thinking the exhaust pressure may be forcing the waste gate flapper open.  I had never ran this loose on the waste gate adjustment before.  I am going to try to increase the tension on the actuator and see what the result is.  Also I will pull the grainger valve off the car and test my last adjustment with air compressor.  It is going to rain today so I don't know how much road testing I will be able to do.

Any one experienced this before?  Any other ideas or something I am missing that is not letting me exceed 20 psi?

[Steve Wood]

typcially, you need an 1/8" tension on the wastegate rod.

Then, your maximum boost will depend upon the strength of the spring in the grainger valve...you may have to shim it or install a stiffer spring

[Scoobum]

If you've ported the exhaust housing...you may have gone too far...and you're boost pressure will only hit a certain point. Never fear...as RJC sells a shim.

[dyermullet]

Thanks I will test the opening pressure on the the grainger valve first and go from there.  I have more than 1/8" of tension on the waste gate rod. 

[Steve Wood]

20 psi is about all I could get out of the grainger valve I used until I modded it