Why is 1 bar of boost 14.7lbs? What made it this exact measurement? Is it because that is the atmosphoric air pressure outside, or is that even the correct word?

 

1 bar of boost is 14.7 PSI. Atmospheric pressure is 14.7 psi, so when talking 'bars' you are really talking a comparison to atmospheric pressure to boosted pressure of your supercharger/turbocharger. most people, when talking boost though, just say the psi. and most times, if someone says they are running two bar, they mean 29.4 psi.... not 14.7 psi, because atmospheric pressure is going to always be somewhat constent... so most people do not account for it.. hope this helps...