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Forum name4G63 Tech
Topic subjectWhy can't I boost past 19psi?
Topic URLhttp://forums.2gnt.com/dcboard.php?az=show_topic&forum=67&topic_id=7756
7756, Why can't I boost past 19psi?
Posted by FlyinEsi, Dec-31-69 06:00 PM
I just got all the hoses ran for the Greddy Profec-B boost controller and when I'm on my low setting at 17psi I creep up to about 18psi but on my hi setting which I have at 21psi I can't get past 19.4.

Any idea why? My only thought is because I have about a mile of hose running around places, not really, but I have like 5 feet running from the wastegate to the valve body, and about 5 feet running from the intercooler pipes to the valve body. Then of course there is like 12 feet running from the fuel pressure line into the main unit in the cab.

Any other ideas if this one doesn't seem reasonable?
7757, RE: Why can't I boost past 19psi?
Posted by PowerEclipses, Dec-31-69 06:00 PM
are you using nylon hoseing or rubber?
7758, RE: Why can't I boost past 19psi?
Posted by FlyinEsi, Dec-31-69 06:00 PM
Rubber.
7759, RE: Why can't I boost past 19psi?
Posted by DR1665, Dec-31-69 06:00 PM
Originally posted by FlyinEsi
Rubber.

Could it be expanding on you? :wary


7760, RE: Why can't I boost past 19psi?
Posted by Jeff_99gs, Dec-31-69 06:00 PM
Originally posted by DR1665
Originally posted by FlyinEsi Rubber.
Could it be expanding on you? :wary


No I use rubber too.

Boost problems like that are usually wastegate related since a boost leak wouldn't really prevent a system from building boost past a certain level (unless a vacuum line completely blew off). I would assume there is a problem with the wastegate or how the boost controller is set up. You may have a vacuum line that has blown off or something similar. I would check all connections and hoses and do a boost leak test as well.
7761, RE: Why can't I boost past 19psi?
Posted by Vandy420a, Dec-31-69 06:00 PM
Dan--

just FYI....I've been having similar issues with my Profec B. I've been working on it for a while...I disconnected the profec and boost was solid, but onlyh about 7-10psi on an evo16g with 34mm wastegate. Which turbo/wastegate combo are you running? I did a leakdown test to no avail---as soon as I get moved in i'm going to switch to a cheap MBC and see if that changes anything. I have a feeling the Profec's just aren't very robust.
7762, RE: Why can't I boost past 19psi?
Posted by Blizare, Dec-31-69 06:00 PM
As far as I've seem a profec control boost is 25 psi.

Never had any problems on the silvia at all but thats only 15psi :P

Yea how much does it run if you shut it off with your turbo/wG setup?
7763, RE: Why can't I boost past 19psi?
Posted by BigBald, Dec-31-69 06:00 PM
What is the attraction with EBC's? I am really curious.
7764, RE: Why can't I boost past 19psi?
Posted by Blizare, Dec-31-69 06:00 PM
Originally posted by BigBald
What is the attraction with EBC's? I am really curious.


Just the fact that i can go from 7 psi to 15 at the push of a button. Not say "hold on, I need to turn up the boost" :P

plus.....when your pushing 7psi and pulling good, you can hit high boost for a sudden extra 8 psi :)
7765, RE: Why can't I boost past 19psi?
Posted by FlyinEsi, Dec-31-69 06:00 PM
Originally posted by BigBald
What is the attraction with EBC's? I am really curious.


Jerrome, what I eventually plan on doing is installing a carputer in the car with DSMlink running off of that on a 7" touch display in the console. That way I can go from low boost to high boost, tell DSMlink to throw on different fuel curves and never have to get out of the car. Plus I wanted to see the difference between what I set the boost at and where it actually goes versus turning a knob hoping it goes up 2 psi only to find out it went up 4 and then I have to stop, pop the hood, and do it all over again.
7766, RE: Why can't I boost past 19psi?
Posted by 97eclipse97, Dec-31-69 06:00 PM
http://www.reitmanracing.com/product_info.php?manufacturers_id=21&products_id=213
7767, RE: Why can't I boost past 19psi?
Posted by kelvinb1, Dec-31-69 06:00 PM
do you have the vacuum line hooked up to the turbo outlet or near it? its possible that the length of piping and intercooler have a pressure drop of 1.7psi. I have my mbc hooked up to the intake manifold, so it is seeing the 15psi at the intake manifold instead of 15psi before the intercooler.
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