What is the air-fuel ratio for liquid petrol

[Rockst4r]

I've been wondering this for a while, I can't figure it out though, it's easy enough for figure it out for petrol vapour, but the problem is with liquids
when Googling it, the ratio 14.7:1 is common, but it seems as if that's for pure Octane.
if someone could also include the method of calculating it, that would be great!

edit: at room temperature :)
edit2: looks as if this has been asked before, sorry about posting this :) I should have searched
https://www.physicsforums.com/showthread.php?t=398511

 

[Navin A S]

The ratio of the vapor pressure of a liquid at a given temperature to the saturation vapor pressure of the liquid is known as the "vapor pressure ratio". This ratio is independent of the type of liquid and is typically expressed in units of atmospheres (atm). The vapor pressure ratio is typically determined experimentally, and is usually close to unity at room temperature.