Originally Posted by littco
Now in theory a well maintained engine shouldn't produce to much water vapour as all the Oxygen should be burnt off, however if the mixture is not correct then you may get a situation where more water can be produced due to excess oxygen.
Check your chemistry...
Hydrocarbons will produce a fixed amount of water when combusted. It's purely a function of how much hydrogen is in the fuel. If there is enough oxygen available, it will pretty much ALL form water vapour.