This site discusses increase in volume of Hydrogen production as a result of temperature. If you know the current Gas Production of your Hydrogen Generator and change of temperature between what it is measured in the lab and what it is under the hood, you can calculate the amount being delivered to your engine.

As the temperature of your system changes so does the amount of Hydrogen it produces. This is important because the amount of Hydrogen,
HHO, Browns Gas, Oxyhydrogen effect octane of your new fuel and it's flame response speed.
This link has a calculator for making this determination: Effects of Temperature on a Hydrogen Generator.

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