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Discussion Starter #1
Hey guys,

I have a 95gt that I swapped a 351w into and put an on3 351 swap kit in.

It's been to the Dyno 2 times and had the same problem both times. The problem being low boost. After the first trip to the Dyno, the on3 turbo had a bunch of play in the shaft and seemed a bit undersized for the job, so I went back with a bigger Borg Warner turbo, but it didn't solve the problem.

For whatever reason, the car makes 5.6psi and nothing more. We've tried 2 boost controllers, 1 electronic,1 manual. And 2 different wastegate springs, none of which made any difference. I'm not sure if we have a huge boost leak or restriction somewhere, or if the boost pressure is floating the valves and just blowing the boost right back out the exhaust?

I brought the car back home to troubleshoot it and figured I would see if someone on here had any ideas to try while I'm working on it this weekend.

Any input would be greatly appreciated!

Thanks!
 

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You could try getting rid of the boost controller. Just connect the line from the discharge of the turbo to the bottom wastegate port.
 

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Discussion Starter #6
You could try getting rid of the boost controller. Just connect the line from the discharge of the turbo to the bottom wastegate port.
We did try doing that once also, just to run it on spring pressure, actually we did it 2 times with both different spring rates and it didn't make a difference.
5.0thunder;17935 906 said:
Make sure the blow off valve isn't cracking prematurely.
Any method to checking that without having to keep someone's hand there while making a pull on the Dyno? I did try to do that just while making like 1psi in 2nd gear on the Dyno, and under vacuum the blow off valve was open, but once it made boost, it appeared to have closed. Now, it's hard to say with absolute certainty that it was closed all the way because the fan was on, and all the air moving around in the Dyno cell makes it nearly impossible to tell that it was definitely closed, but if you have an idea as to how I could test that, I'm definitely willing to give it a shot. I'm pretty frustrated at this point.
 
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