I had been running a sts with a gt67 for quite a few years. I recently swapped up to a kbracing front mount with a mp t-76. Up here where I am it is just getting kinda warm and dry and I have just started tuning and trying to dial in this setup. I was planning on running my sts boost controller at 14psi and when it is off it would be on the 7psi spring in the 38mm tial wastegate.
So yesterday, when running down the highway at 55mph, I can stomp on the throttle and the boost never stops climbing untill I back off the throttle, which I never let get over 12psi. Is my wastegate not big enough for my 370ci motor or did I screw something up somehow. I have gone over my whole setup 3 times tonight, and it still looks correct.
Any ideas? I am thinking that the wastegate is probably big enough or Kb would have said something. So maybe my vac lines are to small/big?

 

Low boost= bigger gate
a smaller gate can work with higher boost, Ie they have less exhaust to bypass @ 14 than @7psi.

 

running 10psi on my tial 38mm and never have any creep..... Not sure but something sounds off. Check your vac source for the ref line, then delete the boost controller to test it. Just have to rule out one part at a time!

 

but he has the 76...more flow in, more exhaust flow out...I think there is a gate that flows more but will bolt up to the flanges you have? but I could be wrong

 

OK, I have been gone for a few days, sorry for the late reply.
I don't even have my boost controller on. I left it off after I pulled it off the frame rail by the sts setup. I wasn't going to put it on untill I got my new setup dialed in on just the wastegate. I did pull the line off the wastegate and had my wife brake stall it for me..... (thought she was going to run me over lol), and there was pressure getting down the line.

I have had a few people tell me that the 38mm should be more than enough. BUT, I am dumping back into the exhaust, could this hinder the performance of the w/g? If there is a bigger w/g then someone tell me, I can always give it a try.

 

Humm... JGS makes a 40mm that will bolt in there. Try taking the spring out of the WG and seeing how much boost it will make with the gate all the way open all the time. if it's making boost still them a 38mm might just be too small for that setup.

 

Kinda weird. I pulled the spring out of my wg. I could over boost it every time I tried to.
Huh. So I just for ***** and giggles, I grab my other 38mm tial I have in the garage and swap the entire wg out. What the hell. Every time I jumped on the throttle from a stop it would do great until I hit 3rd gear. Then it would creep up over 7# and go up over 12# untill I let out. It has a 7# spring in it. So this is a pretty good sign that the wg is to small right?

 

It's looking like it. Some setups just need more WG. Add that second gate to it and should be good.

 

Which would be the better way to fix this and stilll use my electronic boost controller? I really like running around town on low boost and then being able to flip a switch and run high boost and activate my meth.
If I put a second controller on, do I just put a vacuum "t" from the boost controller to the two waste gates? Or would things just be simplier to just put a single larger wg in? Any opinions on size and brands?

 

just wondering here, but you do have the top port open while the controller is not installed right? i've seen people block them off thinking "i don't want anything getting in there" and it not letting the gate open up. i pinch my boost controller hose off on that port before and had over boost issues. i didn't know it was pinched, it happened during a trans install.