3800 Boost - Does this sound right?

[markymarc]

Drove downtown on I90 today expecting to have a nice ride in, which it was. But I noticed after pulling away from the O'Hare toll plaza that at almost full throttle, I was only getting about 6.5 lbs of boost, and 7 lbs at full throttle. The car feels as strong as ever, and there are no problems with anything, so I am not implying a leak, but when the air is colder like this in the morning, shouldn't I be seeing around 8 lbs with a 3.2 pulley?

I do see upwards of 9.5 lbs when it is in the 40's, related to the barometer and all, but what boost level is normal for a GTP with a 3.2, Thrasher, DHP, 1.9's, TOG's, ported TB, DP, and gutted cat? Does this vary car by car?

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[imported_Ron Vogel]

You should be seeing 11 PSI, I'd check for vac leaks. Also make sure you aren't getting any belt slip.

 

[1quick]

prob a blower bace gasket or a vaccume line fiting cracked how is your vaccume at idel mine used to sit right at 20 when my bace gasket blew out it red 17




brett

 

[markymarc]

If I had a leak, wouldn't my idle be rough?

The DIC boost guage seems to match the autometer gauge up through 5 lbs of boost, the max for the DIC at a half lb per square, correct?

Maybe there is a crack or leak in my vaccum line that goes to the gauge, that seems to be the most probable explanation.

How do I test for a leak?

 

[Sinister Drag Designs]

yeah that brings up a good point, at idile mines at 17, but when im on the hi way and im going like 80 or 90 then let off it goes to 20-21, with the 3.4 i get 10lbs and with the 3.25 iget 11- 11.5 does everything sound fine,
o sorry my mods are dub system, 3 dp 3 cat back, tr6 gapped at 54
thrasher intake, msd wires, dei wrapped crossover,
dhp and afc coming soon , would any of my mods cause me to lose boost

 

[MIKES3]

My vacume is always 20 at idle, and at wide open throttle I see about 14 psi depending on the weather. Usually at night with my 3.4 its around 13-14

 

[Sinister Drag Designs]

Originally posted by MIKES3@Jul 31 2005, 07:17 PM
My vacume is always 20 at idle, and at wide open throttle I see about 14 psi depending on the weather. Usually at night with my 3.4 its around 13-14

[snapback]93733[/snapback]​

thats way to much boost, for a 3.4 sounds like u got boost creep , before i did my exhaust i had 9-10 after it was at 7-7.5
do u have any exhaust work

 

[markymarc]

It was two things. 1) Belt slippage and 2) my tubbing that runs to the guage had a crack in it where I fished it onto the T-piece (name?). So essentially it wasn't sealed properly and leaking right there at the start.

I am now getting 11 lbs in 90 degree heat, so that sounds more in line with my pulley size. I wonder what it will be in cold weather.

Thanks for the advice.

 

[sr71_rgl]

Originally posted by MIKES3@Jul 31 2005, 06:17 PM
My vacume is always 20 at idle, and at wide open throttle I see about 14 psi depending on the weather. Usually at night with my 3.4 its around 13-14

[snapback]93733[/snapback]​

That's normal boost for a 3.4" on an otherwise stock motor in colder weather.