Why Air?
Would it be possible to, instead of using air use pure oxygen or something?
If my theory is correct then surely this would increase power, right?
Your theory is correct but there is a flaw. Pure oxygen introduced into a hot cylinder would cause a ignition oxygen alone or if you could get a mixture of pure oxygen and fuel into the cylinder the explosion would destroy the engine.
One: Pure oxygen and fuel mixture is liable to go off in the intake plenum if there's a hot valve, and blow out the entire airflow sensor and throttle body system, it would be far too unstable.
Two: If you manage to get a pure O2/Gasoline mixture into the hot cylinder long enough to get the intake valve fully closed, it /will/ go off prematurely as the compression stroke starts and well before TDC, causing a nasty detonation that will mechanically ruin the engine.
Three: You don't have the storage density for carrying it in a car as compressed Oxygen in tanks, you wouldn't make it more than 30 - 50 miles between tank fills. Liquid Oxygen (LOX) has the needed storage density, but it takes a lot of heat to vaporize it in the quantities needed. More than the waste heat of the radiator in the winter, especially when you add cabin heater loads, and forget about using an ambient air heat exchanger when it's below zero outside - you would have to burn fuel to vaporize the LOX.
Four: Carrying that much LOX around (or even compressed O2) would be a HazMat nightmare. You would be restricted from driving through many tunnels and onto many ferries, and restricted from many bridges and underground parking garages. Too much chance of it going *BOOM!* by accident, and too easy to rig it up to go *BOOM!* on purpose.
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If you used pure oxygen instead of air, it would have the advantage that would be less problems with pollution because nitric oxides would not be formed. And it would probably be a little more efficient because when you're compressing the air/fuel mixture, your also compressing nitrogen.
However, the reaction that converts hydrocarbons (gasoline) and oxygen to carbon dioxide and water and heat would still be the same. I doubt that there would be a significant increase in power, because air is a convenient source oxygen with all the oxygen we need to run a car.
Even if the amount of power were significantly improved, the problem is that pure oxygen is made by liquefying air, which separates the nitrogen and oxygen (oxygen has a boiling point of about -300 F, so it is not something that is easy to do in a car). This would eat up any savings.
Finally, oxygen would require storage tanks on board, oxygen stations to refuel the tanks, and lots of safety equipment, because fires supported by pure oxygen burn a lot faster than fires supported by air (which is why they use oxygen in welding). All of this makes oxygen use impractical where there is free air readily available, which is why only the nice folks in hospitals, airlines (during emergencies) and NASA are the amongst the few people who normally supply oxygen.
Jeff
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