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Discussion Starter · #1 ·
Just wondering what everyone elses is.

Mine with the car stoped at idle is about -.07 mpa +/- .005 (accsesories like lights and blower seem to vary the boost some)

While driving and I take my foot off the gas it drops to about -.09, one tick away from as far as it will go on the factory column mounted boost guage.
 

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Discussion Starter · #3 ·
TurbeauxREX said:
At idle, about 20" vacuum. No positive pressure seen at idle.

Curtis
Forgive my lack of knowledge but what is 20" vacuum?
 

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just below 20 vac, when i got my underdrive pulley it dropped from like 20 to like 23 vac...probobly due to lessened parasitic load.
 

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Discussion Starter · #6 ·
Is that 20 psi? So you are getting 20 psi vacuum. That seems like a lot, Unless my factory boost guage is defective. Mine has always been this way since I got the car, but with two people saying they are getting 20psi in vacum that just seems odd.
 

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psi is pounds per square inch...as im sure you know.....vacuum pressure is measured in inches of mercury im pretty sure...not psi. So you factory boost gauge which measures in bar i think is most likely right, you just misunderstood what we said, its all good.
 

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KanosWRX said:


Forgive my lack of knowledge but what is 20" vacuum?
20" of vacuum is a measure of negative pressure. In our case, it's inches of mercury, negative. With a closed throttle, your engine creates a vacuum. When the throttle plate is opened, you loose vacuum. When you achieve boost, your manifold pressure goes positive, IE: 15PSI, or in your case, some metric value, .01kg. I went with a boost gauge that reads in PSI / vacuum cause I didn't want to deal with converting. Lazy or dumb, whatever. Not to mention, >$200 for the factory boost gauge is plain old rape!

Peace,

Curtis
 

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Discussion Starter · #10 · (Edited)
Thanks for clearing all that up for me. If you had an air leak (like in a uppipe) somewhere would you get more vacuum, or less?
 

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Mine is 0.57 bar at idle, and I run a MBC and a MRT TMIC. Most boost gauges measure off the compressor side of the turbo, and on boost, one can expect a 0.5 to 1.0 bar drop after the charge passes the inetrcooler. So, its hard to say what an up-pipe leak would do to the boost- depends on temperature, intercooler, ect. A small up-pipe leak in a catless turbo should not drop boost that much with a decent boost controller./SIZE]
 
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