Boost gauge bad? Or is it something else?
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From: Columbus, Ohio
Boost gauge bad? Or is it something else?
Hey ya'll got something for ya.
Running a 2.9" pulley, monitoring boost via mechanical Phantom II Autometer boost/vacuum gauge.
I have always observed around 14-15 psi (which I always thought was kinda low for a 2.9")
Saw the other day I was only boosting around 11-12 psi. (Gauge is only about 2 months old). Just being the paranoid **** that I am, I took off the supercharger, intake manifold, inspected any related boost/vacuum lines and seals of everything. Gaskets for both the s/c to i/m and the i/m to head were inspected and turned out to be ok. Inspected the intercooler endplate seal and it's ok. Played with the boost bypass actuator (before and after teardown/re-install) and it's working fine. THERE IS ABSOLUTELY NO PROBLEM WITH THE INTAKE/BOOST SYSTEM.
For reference, when the engine is off and there is no boost/vacuum, the gauge has always read around 3-4 Hg on the vacuum side. Never has been exactly zero. Could this be the boost gauge itself being a factory defect? What are other people boosting on a 2.9" pulley?
Please keep in mind that I have a ZZP mid-length header/ 3" downpipe with 2.5" Hi-flow cat on so I assume that I will drop just a psi or so in boost because of better airflow, am I right?
Running a 2.9" pulley, monitoring boost via mechanical Phantom II Autometer boost/vacuum gauge.
I have always observed around 14-15 psi (which I always thought was kinda low for a 2.9")
Saw the other day I was only boosting around 11-12 psi. (Gauge is only about 2 months old). Just being the paranoid **** that I am, I took off the supercharger, intake manifold, inspected any related boost/vacuum lines and seals of everything. Gaskets for both the s/c to i/m and the i/m to head were inspected and turned out to be ok. Inspected the intercooler endplate seal and it's ok. Played with the boost bypass actuator (before and after teardown/re-install) and it's working fine. THERE IS ABSOLUTELY NO PROBLEM WITH THE INTAKE/BOOST SYSTEM.
For reference, when the engine is off and there is no boost/vacuum, the gauge has always read around 3-4 Hg on the vacuum side. Never has been exactly zero. Could this be the boost gauge itself being a factory defect? What are other people boosting on a 2.9" pulley?
Please keep in mind that I have a ZZP mid-length header/ 3" downpipe with 2.5" Hi-flow cat on so I assume that I will drop just a psi or so in boost because of better airflow, am I right?
Last edited by Tennpenn83; May 30, 2008 at 10:02 PM.
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Under WOT I hit around 11-12psi from 4k up to redline, but it's very inconsistent. 1st gear WOT actually makes the gauge flutter all over the place, and it's impossible to tell any kind of boost in 1st gear. 2nd and up usually only hit 11-12 if I am lucky.
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just thought of something which pully you running? If its nates then there is a possiblity that if could be slipping since its so light weight. your tensioner might not be working that great i noticed this when i had my nates 2.9. since you have a 3" downpipe you will lose some boost but not power due to the fact more air can escape with a bigger downpipe unless you noticed a lot of powerloss i would not be to worries about it
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It's a Smoothflow 2.9" polished aluminum 3 ounce pulley. My tensioner is fine and my belt is not slipping. Both are regularly inspected by myself. Just worked with the tensioner today when removing the belt for when I inspected EVERYthing else related to the intake manifold.
If it were the pulley being lightweight, then it would have always been around 12 psi. A month ago I could consistantly hit 15.
If it were the pulley being lightweight, then it would have always been around 12 psi. A month ago I could consistantly hit 15.
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It's a Smoothflow 2.9" polished aluminum 3 ounce pulley. My tensioner is fine and my belt is not slipping. Both are regularly inspected by myself. Just worked with the tensioner today when removing the belt for when I inspected EVERYthing else related to the intake manifold.
If it were the pulley being lightweight, then it would have always been around 12 psi. A month ago I could consistantly hit 15.
If it were the pulley being lightweight, then it would have always been around 12 psi. A month ago I could consistantly hit 15.
Thread Starter
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From: Columbus, Ohio
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From: Michigan
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Ion Redlines did not get a stock boost gauge unless you got the G85 package (LSD, gunmetal wheels, boost gauge, ladder tach lights)
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Alright guys here's the dyno from earlier today:
As you can see I'm making decent power up to about 5500 rpm where the a/f ratio drops from 13 or so to 12 and then keeps dropping all the way to 6300 rpms, where it's so rich, the tailpipe wideband used can't even read it. At this point, the dyno was cut short at 6700 rpm (300 shy of redline) because the tech didn't want to damage my engine.
The solid slanted HP graph line would have kept going, probably all the way up to around 250 or higher is the a/f ratio had not dropped.
As you can see I'm making decent power up to about 5500 rpm where the a/f ratio drops from 13 or so to 12 and then keeps dropping all the way to 6300 rpms, where it's so rich, the tailpipe wideband used can't even read it. At this point, the dyno was cut short at 6700 rpm (300 shy of redline) because the tech didn't want to damage my engine.
The solid slanted HP graph line would have kept going, probably all the way up to around 250 or higher is the a/f ratio had not dropped.
if it is a mechanical gauge, you should be seeing ZERO on the gauge when the car is off. sounds like its an issue with the gauge to me.
run up to your local autoparts store and buy another one real quick to test. you can always take it back when you're done, at least that is how the stores are out here
run up to your local autoparts store and buy another one real quick to test. you can always take it back when you're done, at least that is how the stores are out here
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From: Columbus, Ohio
if it is a mechanical gauge, you should be seeing ZERO on the gauge when the car is off. sounds like its an issue with the gauge to me.
run up to your local autoparts store and buy another one real quick to test. you can always take it back when you're done, at least that is how the stores are out here
run up to your local autoparts store and buy another one real quick to test. you can always take it back when you're done, at least that is how the stores are out here
regardless of what the dyno showed, the gauge should show 0 when the car is off. if its not, there is a problem with the gauge. im not saying there aren't other problems with your car.
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