A gallon of gas contains 120,000 BTU of heat energy.
A cubic foot of pure hydrogen contains 325 BTU.
28 liters per cubic foot.
HHO is only 12.5% by weight hydrogen (the only part that is fuel).
1 liter of PURE (no oxygen) hydrogen contains 325/28 = 11.6 BTU of energy.
1 liter of HHO contains 11.6/8 = 1.45 BTU of potential heat energy.
You would need 120,000/1.45 = 82,759 liters of HHO to replace each gallon of gasoline, to supply the exact same amount of BTU of heat energy.
regards
gary
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