| I was looking through the posts from when i was away, and I saw a discussion of the conversions from bar and kg/cm^2 to psi, specifically this post: La-Z-Link Well, I was definitely the one who was vehemently proclaiming that 1 bar = 14.2 psi when we were dynoing my car. I have the avc-r, which displays units of boost in kg/cm^2, and this was the conversion that I meant. so... 1 kg/cm^2 = 14.2 psi (this is what the avc-r displays)
1 bar = 14.5 psi
1 atm = 14.7 psi They're totally different units that just end up having similar absolute values. 1 kg/cm^2 is just a pressure measurement relating one kilogram resting on a square centimeter with gravity pulling it down (if you think about it, kg/cm^2 isn't really a pressure measurement, it should be kg x g / cm^2, but we assume that g is constant and = 9.8 m/s^2, since pressure is force divided by area, not mass divided by area). It ends up being slightly less than a bar 1 bar is equal to 100kilopascals. One pascal is equal to one newton per square meter. Very simple, its just the basic unit of pressure in the SI world, (force divided by area). 100,000N/m^2 = 1 bar 1 atm is just the pressure of the atmosphere at sea level. It happens to correspond somewhat closely to 1 bar and 1 kg/cm^2, but in reality, those two other measurements were chosen in the units they are to correlate closely with atmospheric pressure. It gets very bulky when you have to talk about a pressure being 180,000 N/m^2... think of the boost gauge :-) And kg/cm^2 was chosen because it too ends up having units close to an atmosphere - it isn't g/cm^2 or kg/m^2, because again, those units would be cumbersome to use. In my close minded amero-centric (is that a word?), all of these units are unsuitable for use when talking about pressure in a turbo application. A proper scale would go from 0 to 10 or 25 or 50, not from 0 to 1.25 or 1.8 Turns out we have a pretty good scale already... psi :-)
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Joe
Sport 530bb/Inconel
AIM: hoyatiger81
510rwhp/520rwtq at 23 psi
"You probably never even got you hands dirty working on a car. Take care toolbox!" --djtz1
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