Originally Posted by M&M
So now. Go to 5000ft. I know the proportion is the same. What absolute amount of oxygen is there in one cubic foot of air? Is it the same as at sea-level?
But that "quality" of the extra air is poorer, so you need to add even more boost to get the same oxygen content in.
Make sense? Maybe I should have googled it instead of shooting from the hip with my personal experience of forced induction cars at altitude. I must say it's a great discussion as no-one really knows the real truth up here as most research is done at sea-level. So if we can learn, it will be for the benefit of all us mile-highers on this forum.
We are all on the right track, only thing I disagree with you and so does Ersin, is that partial pressures are different at 0 and then 5000 ft, not quality of air.
Air is air, same composition at ALL altitudes. (20/80 Oxygen/Nitogen) The second you compress air to a certain pressure, provided temps are the same, then the amount of USABLE O2 is the same at both altitudes. Hence the denser the air, the higher partial pressure of O2 in it, and the more fuel you can burn.
But its academic, your technical knowledge of pressure laws are not up to par, but your understanding of tuning is
When you go scuba diving and breath compressed air at depth, the partial pressures of O2 and Nitrogen, increase by one atmosphere per 10 meters you go down. Nitrogen becomes toxic as you approach depths of greater than 40 meters, hence why commercial divers dive with air mixtures, that substitute Nitrogen and or reduce it. All relates to partial pressure.