significant increase in boost...why?...how?
Dec 20, 2006 | 08:57 AM
#1
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From: Dallas, Georgia
significant increase in boost...why?...how?
Originally Posted by Superado
went WOT from a roll this morning...45 degrees outside...tranny downshifted...afr went to 11.5...boost jumped in at about 6 #'s...started climbing again...thought last time was a fluke...thought that it would peter out at about 8 #'s...NOPE...climbed to 7...8...9...10...11...12...I got out of it...wtf!?!
I am confused!
I thought by freeing up the exhaust that I would probably lose a pound of boost...which was 8 #'s w/ cats...
spoke w/ ProCharger...they said they didn't have an answer for me...
the first thing they said was that I had a major restriction somewhere...asked me if I changed muffler when I got rid of cats...NOPE...
someone else asked about the blow-off working...but hell, if it wasn't working properly I wouldn't see increased boost @ WOT...and anyways, I can hear it when I let off...
I am confused!
I thought by freeing up the exhaust that I would probably lose a pound of boost...which was 8 #'s w/ cats...
spoke w/ ProCharger...they said they didn't have an answer for me...
the first thing they said was that I had a major restriction somewhere...asked me if I changed muffler when I got rid of cats...NOPE...
someone else asked about the blow-off working...but hell, if it wasn't working properly I wouldn't see increased boost @ WOT...and anyways, I can hear it when I let off...
Dec 20, 2006 | 11:35 AM
#3
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From: Dallas, Georgia
not sure but doubtful...same guys that fabbed my inlet to tb...haven't dyno'd it but sotp meter feels great...it was climbing when I backed out of it @ 12#'s on the gauge...
Dec 20, 2006 | 11:43 AM
#4
I felt a HUGE, I mean A HUGE diffeence from 9#'s to 10#'s. Did you feel like you were in a rocket ship at 11#'s? Should of started pulling it's *** off after 9#'s. Otherwise...something else is wrong if it wasn't pulling like a monster IMO. Gauge reading messed up? Something simple?
Dec 20, 2006 | 01:55 PM
#7
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From: Deep in the seedy underworld of Koonerville
I was thinking gauge problems too. Anyone around you can borrow another gauge from or do you have a small pump of some sort with a gauge on it that you could test your truck gauge against?
Now that it is cold in the morning up here I do see about 1-1.5psi more boost than I did at the end of summer. I can't imagine a difference of 4+psi due to weather though.
Did you put a new belt on it or anything? Is the truck running rough at all, maybe a bent pushrod or collapsed lifter not opening a valve all the way creating a "backup" in the intake?
Now that it is cold in the morning up here I do see about 1-1.5psi more boost than I did at the end of summer. I can't imagine a difference of 4+psi due to weather though.
Did you put a new belt on it or anything? Is the truck running rough at all, maybe a bent pushrod or collapsed lifter not opening a valve all the way creating a "backup" in the intake?
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Dec 20, 2006 | 02:35 PM
#9
Maybe your procharger was designed for a stock exhaust and too little backpressure is causing extreme boost creep. What other restrictions are in your exhaust? Muffler? You may need some backpressure to maintain normal boost readings or tune for the 13#'s your now getting 
Dec 20, 2006 | 02:41 PM
#10
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From: Dallas, Georgia
Magnaflow SS single-side cat-back...that's it...
Jerry has pointed out that maybe the huge difference was due to the extreme change in temp and the fact that I have small 2-core IC...he checked one of my "with cats" logs that showed me starting @ 104 and ending up @ 158 at the end of the 1/4...and maybe if I had a larger IC before, that there wouldn't have been such a wide range of difference now...also, my IC is mounted parallel to the ground with no sort of air dam on it...
Jerry has pointed out that maybe the huge difference was due to the extreme change in temp and the fact that I have small 2-core IC...he checked one of my "with cats" logs that showed me starting @ 104 and ending up @ 158 at the end of the 1/4...and maybe if I had a larger IC before, that there wouldn't have been such a wide range of difference now...also, my IC is mounted parallel to the ground with no sort of air dam on it...
Last edited by Superado; Dec 20, 2006 at 02:51 PM.