Oh, and, by the way, propane is NOT the best, ideal, blah blah fuel for a motor engine.
[glow=blue,2,300]Methane [/glow] is the ideal fuel.
Methane, CH4 + 2xO2 = CO2 + 2xH2O
one molecule of methane + 2 of oxygen will give you
one molecule of carbon dioxide and two of water.
Simple as that !!!
Maurizio