I am kinda confused here...

I keep seeing mentioned (here, TST's site, etc.) that the boost on my 98 12v truck should not be as high as I am seeing. I have seen boost (unloaded, WOT) as high as 24-25 psi, and boost in excess of 20 psi is not uncommon.

Yet I read
here and it sure sounds like the wastegate should have been opening sooner and not letting me see this much boost?

I am about to install a used TST #10 fuel plate, and was considering calling TST to pick up the boost elbow to go with it, but if I am already getting what seems to be decent boost (especially considering intake/filter/exhaust are all stock), it seems there is little reason to add the boost elbow...

Stock plate has not been touched, and I have not looked but I assume the wastegate has not already been modified.


Can someone shed some light on this for me? Thanks!

 

Ok, doing some reading @ TDR, it seems these numbers are *not* all that high as I first thought?

 

The wastegate on a '98 should set at 23 psi from the factory.

 

So it *is* odd that I am seeing in excess of that? Perhaps I should do some inspection to see if the PO modified something at the wastegate...

 

Things just got even stranger...

Installed #10 TST plate, and took her for a quick drive around. I managed under WOT to reach a whopping 32 psi

Should I be scared? I forgot to check & see if something had been done to the wastegate - I have not modified anything to do with it at all.

 

DRM, 32 psi is pushing the upper limits of your turbo, just try not to exceed 35 psi.
How does it run with the #10?
Your wastegate could be stuck or the diaphram could be shot.

 

You could have a hole in your diaphram.It could be your drive pressure that is opening the valve.

 

Well, I noticed yesterday that at WOT I can get 34 psi out of the boost.

I don't know what the wastegate opening is supposed to act like, but I get no indication that this thing is bleeding off at all from the way it is acting.

I got this truck a little over a month ago bone stock, and have since added the mods listed below... So it kind of worries me about the boost being so high and possibly blowing something.

How would I check the wastegate and diaphram?

 

Disconnect the hose from the wastegate actuator and use an air compressor to see if the actuator rod moves. !!! DO NOT EXCEED 35 PSI !!! you can blow out the diaphragm.

 

I'll regulate the pressure down on the compressor and try it this weekend, thanks!

 

just disconnect the line to your waste gate david, you can't over boost the motor with your mods. and quit worrying about it unless you are going over 38 to 40. mine has seen 50 many times and hits 42 right now with a 14cm ex housing. i need to get it back to 38 to 40.

 

So you are saying I should not be worried about 34-35 psi of boost on a stock motor with close to 300k miles? Hmmm...

 

Well, I noticed on my trip last weekend doing some towing that I can get it to hit 36 psi of boost if I don't regulate the skinny pedal... I guess I still need to check the wastegate

 

why bother, that is just fine as far as boost goes, i have 240 k on mine and it see's over 40#s all the time.

 

No abnormal noises, shudders, or whines I could tell - and it sure is easy to hit 36....