off of this link..
http://www.gnttype.org/techarea/turbo/turboflow.html
i found this math,
"Example: a boost gauge reads 0 psi before it is hooked up. Hook it up, boost the car, and it reads 17 psi. 17 psi is the gauge pressure, the absolute pressure at sea level is 14.7 + 19 = 33.7.
A pressure reading is marked psia or psig. The "a" stands for absolute, the "g" for gauge. (The psi stands for Pounds per Square Inch). As we just showed, 17 psig = 33.7 psia. A perfect vacuum is 0 psia, or -14.7 psig."
i thought the absolute pressure was whatever boost your running + 14.7 psi. so wouldnt that be 14.7+17 =31.7 or maybe im just confused. if what they say is correct how do we find out the psia at different amounts of boost?
(Added Late) earlyer that same page describes absolute pressure exactly how i thought it works:
"Absolute pressure is the gauge pressure (measured by a gauge that reads 0 when it is open to the outside air) plus atmospheric pressure. Atmospheric pressure is about 14.7 psi at sea level."
P.S. sorry if this has been posted about before, i didnt find it
P.S.2 Woot.. i read the whole thing.. i feel enlightened lol. I still belive that was a mistake.. oh well though.. maybe ill mail them about it later.