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low boost after intercooler

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ImpalaGTP

New member
I recently finished an phenolic intercooler install on a 02 gtp and the car seems low on boost. before the intercooler I had a 3.4 pulley an it made around 7psi in this very bad air we have in Tucson (made 10 in the winter and had noticeably more power). upon completion of the intercooler I took it out with the 3.4 still on and only had between 4 and 5 psi so I checked and rechecked for a vacuum/boost leak and could not find a thing, fuel trims looked good as well so I put on my 3.25 pulley and now I'm seeing 6-6.5 psi. belt doesn't seem to be slipping, no knock nothing seems wrong outside of the boost and power level I feel it should be at. Is it just the air is that bad?
 


Does the lego block go to full and stay there or does it go up a little way or does it go up and come back down a block? If it doesn't go up all the way and stay you have a vac leak somewhere or the intercooler didnt seal.
 
forgot to mention it has sd headers, vs cam, ls6 valve springs, single roller timing chain, hot air intake, zzp tune, al104 cat and egr delete
 
it goes till there is like 1 block left and stays there. but I have been watching other gauges more closely don't really pay attention to the lego blocks.
 
Check the BBV setup.. Seems to be a common issue and almost always is a bad BBV or a vacuum leak of some sort near the FPR T-fitting or the Boost solenoid, etc..
 
97AutoXVette said:
Check the BBV setup.. Seems to be a common issue and almost always is a bad BBV or a vacuum leak of some sort near the FPR T-fitting or the Boost solenoid, etc..
Click to expand...
I removed the bbs and replaced all the vacuum lines the first time this happened also checked the bbv and it seems to be working. Is there a way to force it closed just to be 100% sure it's not the culprit?
 


I mostly drive around speedway and go to the drags off of Houghton road. After I get this turbo done I'll be headed back up.
 
Just read your thread, badass car. I've seen a few fast g8s running around but no gps. SIR is off Houghton, what did you run?
 
all i could manage was high 13 that night DA was at like 5000 ft that night, Even a pullied down CTS-V on E85 could only pull down high 12's. Hot and ****ty there at that track lol. Next time im up there itll be with a TT vette a friend and i just built and tuned.
 


Yeah nobody believes me when I tell them how slow this track is, it breaks hearts. stock ls1 f body's are in the 14s. I Hope I hit the 13s with this intercooler setup.
 
So I found a vacuum leak and fixed it and it didn't help at all with the boost just took it out and barley got above 5psi.
 
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