What is the most efficient and complete combustion of gasoline 9how many parts of atmospheric aer for every 1?

i think thats sort of a loaded question actually, arguably 15.4 is better than any other one listed but i think that 14.7 to one is the accepted average for gas to give complete combustion under normal conditions. but ill say 15.4 to one uming the engine can run stable at that mixture and it has no EGR.