A rough quick WAC (wild ass chemistry) calculation based on nitrogen content of air and gas (the only constant parsmeter in both):
(6N2 + 1.5O2) --> (5N2 + 2H2 + 3CO)
this is a SORT OF equalized reaction so:
7.5 moles at air end (left) and 10moles at gas end (right).
Moles equal volume at same temp. so 75 liters of air produce 100 l of gas. Not puting moisture, CO2, higher gas temperature, and other parimeters in to count.
My highschool profesors wuld bang their head at the wall if they saw this calculation