OK...trying to get this millibar to psi conversion straight...

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Jul 25, 2004 | 03:10 PM

fourwheelslide

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OK...trying to get this millibar to psi conversion straight...

...Pro-Diag is spitting out a peak boost of 2320 millibar...I subtract 1000 and then divide by 1000 and multiply by 14.5? Is that correct...can anyone tell me why I subtract by 1000 first...is this to accomodate for vacuum pressure. I KNOW I'm not spiking at 33.64 psi (2320/1000 x 14.5), but 19.14 ((2320-1000)/1000 x 14.5) sounds right. Thanks in advance!

Jul 25, 2004 | 03:20 PM

duct tape

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no clue what the hell your saying but maybe this might help

<ul><li><a href="http://www.ilpi.com/msds/ref/pressureunits.html">http://www.ilpi.com/msds/ref/pressureunits.html</a</li></ul>

Jul 25, 2004 | 03:27 PM

fourwheelslide

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My point is...

if use a straight millibar to psi conversion (as is in your link), I get 33 psi of boost...IMPOSSIBLE. You have to subtract something off of the millibar number in order to accommodate for vacuum and altitude. Just trying to see what the consensus is in how much that subtracted number should be. Thanks for the link though...bookmarked it for future reference.

Jul 25, 2004 | 03:39 PM

duct tape

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i think i remember reading up on exactly what you're talking about.....

I'll post it if I can find the article.

Jul 25, 2004 | 04:18 PM

Audragon

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Are you using excel to calculatethe curve data?

if so set it up to subtract the value that shows up as the idle(atmospheric pressure?) value. it seemed to vary for me from time to time, from 970-1020 or so.

Jul 25, 2004 | 05:16 PM

fourwheelslide

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Idle for me (Denver) is 830: 22 psi peak boost...not bad.

Jul 25, 2004 | 06:08 PM

Jet Jockey/A4 Pilot

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From: Montreal, Canada

2320 is the total pressure incuding the barometric pressure at your altitude...

What you need to substract from that 2320 was the figure when the engine was off (I don't know about when it's at idle), this is the actual barmetric pressure at this instance in your area.

Assuming for arguments sake it was 1000, then take the 2320 - 1000 = 1320 MB.

Now 1320 Mb = 1.32 bar (1320/1000).

1.32 x 14.7 = 19.404 psi