What does your boost gauge read when...

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01-12-2004, 11:32 AM

frisco-wrx-dude

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What does your boost gauge read when...

Hey there

Quick question

What does ur boost gauge read when ur at "idle" and when ur off the gas/throttle pedal when cruising on the highway. (i know you should be in vaccum, but what vaccum psi are you at?)

I just want know to do some comparison.

Thanks

So far, for me, i'm hitting (during idle) around -15psi or so and a lil over -20psi when cruising on the highway when off the pedal.

01-12-2004, 11:43 AM

Salty

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Re: What does your boost gauge read when...

Quote:

Originally posted by frisco-wrx-dude
Hey there

Quick question

What does ur boost gauge read when ur at "idle" and when ur off the gas/throttle pedal when cruising on the highway. (i know you should be in vaccum, but what vaccum psi are you at?)

I just want know to do some comparison.

Thanks

So far, for me, i'm hitting (during idle) around -15psi or so and a lil over -20psi when cruising on the highway when off the pedal.

Sounds a bit low. Try unconnecting the neg terminal on the battery to reset it and see if it changes. I should be at a vacuum but i don't think that low. Does it go back to "0" when you turn off the car or does it set at around 5-10 mmHg?

EDIT: mine is at about 16 mmhg at neutral and at about 13 mmhg in gear.

Last edited by Salty; 01-12-2004 at 01:59 PM.

01-12-2004, 12:04 PM

HTM WRX

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at idle i'm at -13-15 mmHg(millimeters of mercury, not psi) and when i'm moving and off throttle i'm at -20 mmHg

01-12-2004, 12:10 PM

RussB

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same here. -15 mmHg at idle, -20mmHg when decellerating.

01-12-2004, 08:55 PM

frisco-wrx-dude

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cool, i thought something mighta been wrong, cuz I swore that it wasn't that low, but maybe it is..

Thanks guys

01-13-2004, 10:57 PM

Kean

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Frisco, If your gauge reads PSI (positive pressure; above "0"), then it most likely reads in InHg - inches of mercury (vaccuum; below "0") and not mmHg. .......most likely.

Mine reads in PSI/InHg and is similar to the readings you get (I'll have to check). Obviously, various conditions will affect your readings (engine load, altitude, etc).

- Kean

01-14-2004, 11:54 PM

DanZ

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Which boost gauges do you guys have? I have a Blitz and it reads -.59-(-.63) bars at Ilde. Does that make sense? Is it the same as mmHg? Numbers seem way different. Can someone please explain? Thanks, Dan

01-15-2004, 06:38 AM

Nesquik

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I am not sure what the correct pressures should be but:

1 bar = 14.5 ~ 14.7 psi (I think it's 14.7 (atmospheric pressure))
1 bar = 760 mmHg (I think)
1 psi = 51.7 mmHg

So,

-0.59 bar = -8.5 psi , - 442.5 mmHg?

Do the mmHg gauges read in hundredths or something?

Last edited by Nesquik; 01-15-2004 at 06:45 AM.

01-15-2004, 12:27 PM

Kean

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Quote:

Originally posted by DanZ
Which boost gauges do you guys have? I have a Blitz and it reads -.59-(-.63) bars at idle. Does that make sense? Is it the same as mmHg? Numbers seem way different. Can someone please explain? Thanks, Dan

Personally, I have Omori gauges that read in Imperial measurements: PSI (for pressure) and InHg (for vacuum). It looks as though your gauge in fact reads in "bar" for both pressure and vacuum. If so, -.59 to -.63 would be equal to 17.4 to 18.6 InHg (inches of mercury). ........this is normal.

- Kean

01-15-2004, 12:39 PM

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gilmore25

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on cold starts it usually stays at -.06 and when warmed up it idles at -.07 and usually stays there when i'am on idle, when coming off the gas it's almost at -.1 bar

01-15-2004, 12:44 PM

#11

Kean

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Quote:

Originally posted by Nesquik
I am not sure what the correct pressures should be but:

1 bar = 14.5 ~ 14.7 psi (I think it's 14.7 (atmospheric pressure))
1 bar = 760 mmHg (I think)
1 psi = 51.7 mmHg

So,

-0.59 bar = -8.5 psi , - 442.5 mmHg?

Do the mmHg gauges read in hundredths or something?

Close enough.....

1 bar = 14.5 PSI
1 bar = 750.1 mmHg

The gauges that I've seen that read in mmHg for vacuum will display actual #'s (i.e. 500, 700, etc), and some other measurement for positive pressure (i.e. bar). It all depends on the manufacturer and what type of measurement they decide to go with.

- Kean