not building boost
not building boost just got my t72 installed and its all running good... except the main thing... no boost lol
i can get a little over 1psi with a 5lb spring... im running a t72 rear mount with a cx racing 31x12.??x3 fmic
i have the boost guage hooked right into the intake manifold so i know its right... i also know its right cause im making alot of noise but not going anywhere faster...
i check for leaks and cant find any... could it just be the spring is too weak for how much pipe im running? i have a boost controoler and i will be putting it on friday to see if that helps...
also when i rev i can rev all the way up to 5k and it wont go above 0 psi it stays right at 0 and then does the normal -20 or whatever
i can get a little over 1psi with a 5lb spring... im running a t72 rear mount with a cx racing 31x12.??x3 fmic
i have the boost guage hooked right into the intake manifold so i know its right... i also know its right cause im making alot of noise but not going anywhere faster...
i check for leaks and cant find any... could it just be the spring is too weak for how much pipe im running? i have a boost controoler and i will be putting it on friday to see if that helps...
also when i rev i can rev all the way up to 5k and it wont go above 0 psi it stays right at 0 and then does the normal -20 or whatever
im not sure what you mean.. but its a copy of the sts kit so its right next to the turbo.... if you know where that is
this is just a mock up but you see where it is
this is just a mock up but you see where it is
Move that to the manifold, the same place where your boost gauge is referenced from.
Then, have you checked for leaks by blocking off the piping and pressurizing it with an air compressor?
Then, have you checked for leaks by blocking off the piping and pressurizing it with an air compressor?
no thats the next step... i have heard of people doing that... so i will figure out how to make one... but your saying move the wastegate to the manifold? how the heck does that work lol or are you saying where to plugs into the turbo at?
It works by seeing actual manifold pressure, not pressure at the turbo. Which in a rearmount turbo is generally higher.
Trending Topics
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
so hey, im having a simular issue where im not building any boost past 0psi. i saw 1 psi once but other then that its stuck at 0psi. i did a boost leak test and fixed all the charge side leaks. (BOV and a coupler were leaking) fixed the exhasut leaks that i knew of or found. I even had the wastegate referenced to the manifold but it was still doing this. so i moved it to the compressor and its still doing it. ill put it back to the intake manifold once i figure this out.
ive got a very simular setup to yours but im using a T76. im not getting it?! ive ran into a few forums were some said the injectors, some had clogged cats... (which with mine is impossible or the turbo wouldnt spool at all lol
My turbo is spooling hard and the BOV lets me know about what little pressure its is building when i release the throttle.
im just at a lose.... getting agrivated. the car has been tuned to run with a 2bar map and a 60lbs injectors but havnt been able to boost to finsh the tune! what am i doing wrong?!
ive got a very simular setup to yours but im using a T76. im not getting it?! ive ran into a few forums were some said the injectors, some had clogged cats... (which with mine is impossible or the turbo wouldnt spool at all lol
My turbo is spooling hard and the BOV lets me know about what little pressure its is building when i release the throttle.
im just at a lose.... getting agrivated. the car has been tuned to run with a 2bar map and a 60lbs injectors but havnt been able to boost to finsh the tune! what am i doing wrong?!
TECH Enthusiast
Joined: Mar 2012
Posts: 728
Likes: 3
What are you using to test for leaks? We use a special fitting made to connect an air line directly to the compressor inlet and pressurize the entire intake tract to 20 psi. The method makes it much easier to hear leaks. If your car idles fine, its most likely a leak between the throttle body and compressor. if all of your couplers seal fine, check any and all lines coming from your cold side, especially the blow off valve. If its not routed correctly, the pressure in the cold side will hold it open.
Teching In
Joined: Feb 2009
Posts: 48
Likes: 0
From: Western Australia
It could be the amount of exhaust pressure pushing the gate open too soon. I had this problem and needed to run the heavy spring in my jgs gate as well as a boost controller on the top port with the bottom port straight off the compressor. I didnt have 0psi like you but around 3psi, still worth thinking about.
i used a cap from the tune shop that they use for boost leak tests. it had a fitting on it to hook up air to it. i heard those leaks and patched or sealed them back up. it was also easy to see them casue of my previous over oiling issue i had before lol so oil was being blown out anything that could leak lol including a methanol nozzle that i didnt tighten enough i guess. that was all sealed up now.
The car idles great. no issues there
The reference lines all tie into a vacuum manifold between the brake booster and intake manifold (until recently with the wastegate to see if the vaccum was messing with the wastegates seal)
all those are new. the BOV hose is a 6mm tubing that runs from the Brake booster line to the front right side of the car where the BOV is.
All reference lines are either clampled or ziptied to their connections.
All charge pipe couplers are clamped tight and sealed
The BOV was a tad too loose so i tightened the adjusting screw to hold down the valve a bit more. now it relieves pressure when i get up to 35 mph where as before i wouldnt unless i was getting to 45-50mph in a hurry lol im wondering if i should tighten it even more. it was up when it was idling before, now the valve isnt as high off the seat as before at idle. it also gets to -4vac faster ive noticed where before it got to -6 quickly and then slowly worked its way up to 0psi
i have have a second BOV and pipe kit sitting in the garage. i might test it out and see if the other BOV works better. i know i have an auto but a BOV still is a good idea. im still creating a sudden blockage when i release the throttle so the BOV does do its job when i release suddenly.
The car idles great. no issues there
The reference lines all tie into a vacuum manifold between the brake booster and intake manifold (until recently with the wastegate to see if the vaccum was messing with the wastegates seal)
all those are new. the BOV hose is a 6mm tubing that runs from the Brake booster line to the front right side of the car where the BOV is.
All reference lines are either clampled or ziptied to their connections.
All charge pipe couplers are clamped tight and sealed
The BOV was a tad too loose so i tightened the adjusting screw to hold down the valve a bit more. now it relieves pressure when i get up to 35 mph where as before i wouldnt unless i was getting to 45-50mph in a hurry lol im wondering if i should tighten it even more. it was up when it was idling before, now the valve isnt as high off the seat as before at idle. it also gets to -4vac faster ive noticed where before it got to -6 quickly and then slowly worked its way up to 0psi
i have have a second BOV and pipe kit sitting in the garage. i might test it out and see if the other BOV works better. i know i have an auto but a BOV still is a good idea. im still creating a sudden blockage when i release the throttle so the BOV does do its job when i release suddenly.
It could be the amount of exhaust pressure pushing the gate open too soon. I had this problem and needed to run the heavy spring in my jgs gate as well as a boost controller on the top port with the bottom port straight off the compressor. I didnt have 0psi like you but around 3psi, still worth thinking about.
for right now i have a 10lbs spring in there. im curious if i should put the 4lbs spring in there with it to add alittle more spring pressure. im thinking im gonna get a manual boost controller to see if i can keep the gate closed longer.
im not sure if the wastegate is opening though since im not seeing any oil coming out of the wastegate side of the piping like i can on the exhaust side. ill have to see it while someone else in the car
TECH Resident
Joined: Jul 2010
Posts: 905
Likes: 0
From: VA
i had a homemade STS style kit on my car for alittle while, had kinda the same issue, heres what i found if any of this helps.
also if u haven't tried this (yes its not great for your breaks so dont do alot but) hold breaks and gas at same time while driving and see if u can get any boost out of it, i have a manual so i would stay in gear at like 2-2.5k rpm and hold breaks and floor it and i EVENTUALLY could get my 4psi i was looking for but took longer then should.
things i found were a bunch of exhaust leaks, a loose coupler and a leaking BOV
it made a big difference once most the exhaust leaks were fixed and and i tightened down my BOV, with a 1.00AR hot side turbo could gun it through 2nd and hit 4psi np
also i had my waste gate reference tied in near the turbo with out a problem
i had a check valve in my PCV line but no in my break booster, if u dont have on in ur PCV line i heard u can boost past ur PCV valve to ur crank case and loose boost there
also if u haven't tried this (yes its not great for your breaks so dont do alot but) hold breaks and gas at same time while driving and see if u can get any boost out of it, i have a manual so i would stay in gear at like 2-2.5k rpm and hold breaks and floor it and i EVENTUALLY could get my 4psi i was looking for but took longer then should.
things i found were a bunch of exhaust leaks, a loose coupler and a leaking BOV
it made a big difference once most the exhaust leaks were fixed and and i tightened down my BOV, with a 1.00AR hot side turbo could gun it through 2nd and hit 4psi np
also i had my waste gate reference tied in near the turbo with out a problem
i had a check valve in my PCV line but no in my break booster, if u dont have on in ur PCV line i heard u can boost past ur PCV valve to ur crank case and loose boost there
i had a homemade STS style kit on my car for alittle while, had kinda the same issue, heres what i found if any of this helps.
also if u haven't tried this (yes its not great for your breaks so dont do alot but) hold breaks and gas at same time while driving and see if u can get any boost out of it, i have a manual so i would stay in gear at like 2-2.5k rpm and hold breaks and floor it and i EVENTUALLY could get my 4psi i was looking for but took longer then should.
things i found were a bunch of exhaust leaks, a loose coupler and a leaking BOV
it made a big difference once most the exhaust leaks were fixed and and i tightened down my BOV, with a 1.00AR hot side turbo could gun it through 2nd and hit 4psi np
also i had my waste gate reference tied in near the turbo with out a problem
i had a check valve in my PCV line but no in my break booster, if u dont have on in ur PCV line i heard u can boost past ur PCV valve to ur crank case and loose boost there
also if u haven't tried this (yes its not great for your breaks so dont do alot but) hold breaks and gas at same time while driving and see if u can get any boost out of it, i have a manual so i would stay in gear at like 2-2.5k rpm and hold breaks and floor it and i EVENTUALLY could get my 4psi i was looking for but took longer then should.
things i found were a bunch of exhaust leaks, a loose coupler and a leaking BOV
it made a big difference once most the exhaust leaks were fixed and and i tightened down my BOV, with a 1.00AR hot side turbo could gun it through 2nd and hit 4psi np
also i had my waste gate reference tied in near the turbo with out a problem
i had a check valve in my PCV line but no in my break booster, if u dont have on in ur PCV line i heard u can boost past ur PCV valve to ur crank case and loose boost there
im referencing the wastegate to the compressor for now until i get all the leaks out of the way. i did have the wastegate referenced to intakemanifold but i wasnt sure if the vacuum when out of boost was messing with the wastegate so i have it only seeing boost for now.
as for the PCV, that was taken care of well in advance...
i have a LS6 valley cover that goes into a catch can, then a check valve and into the intake manifold. the drivers side valve cover is blocked off, and the passenger has the rear blocked off, and the front one is ran all the way to the fresh air intake so that it always creates a vacuum on the crank case.
im actually really suprised im not making ANY boost lol i always heard the horror storys of guys not tuning their cars and boosting them and destoying their motors lol but i cant even get more then 0psi lol
TECH Resident
Joined: Jul 2010
Posts: 905
Likes: 0
From: VA
thats intersting, even with all my issuses before i fixed them i could MAKE the car see maybe 2-3PSI brake boosting it. for the BOV what i did is sat in the parking lot and just hit the TB by hand while under the hood with one hand over hte BOV to feel the air, i did it till i could feel it sealed until i reved it and when i left off it opened, besides that it was sealed till i revved and let off, i didnt make any boost on my gauge when ever i reved it but if i just hit it by hand u could still fill air blowing out of hte BOV alot
****, i cant even get boost brake torquing right now 
Im starting to suspect that im gonna be another auto without a BOV lol cause if this bastard dont start acting right, its getting tossed lol
Im starting to suspect that im gonna be another auto without a BOV lol cause if this bastard dont start acting right, its getting tossed lol TECH Resident
Joined: Jul 2010
Posts: 905
Likes: 0
From: VA
if ur bov is sealed might be something else, the turbo sound like its spinning up or not really?
also idk if this is anytjing with u, just thought ofnit though, i had an oiling issue and my theory on it was, i had oil building up in the turbines and was slowin down the turno and incouldnt hit boost for a day or so, well i also have a 2step so running out of things to try i turned my 2step up to about 3800rpms, watched my boost gauge and stayed on the 2step, i got maybe 1psi but when i pet off the gas car backfires loud as hell, and this time did it with a puff of blew smoke, after that it spooled alot better, so idk if that "cleared" out the turbo or was all coincedencd but might be worth cleaning turbo fins or checking
also idk if this is anytjing with u, just thought ofnit though, i had an oiling issue and my theory on it was, i had oil building up in the turbines and was slowin down the turno and incouldnt hit boost for a day or so, well i also have a 2step so running out of things to try i turned my 2step up to about 3800rpms, watched my boost gauge and stayed on the 2step, i got maybe 1psi but when i pet off the gas car backfires loud as hell, and this time did it with a puff of blew smoke, after that it spooled alot better, so idk if that "cleared" out the turbo or was all coincedencd but might be worth cleaning turbo fins or checking