What I know is HHO also called brown gas, its true and practical to use as alternative fuel, but not the way HHO kit makers promise eg (HHO on demand). It's not possible to produce enough gas to run the same engine. The practical way is to make HHO from engine raw power and store in storage tank and use when needed. But its very dangerous because hydrogen ignite fasrer then gasoline. I once had experiment but in very small scale. It's better to some extent for stationery power plants like generators.
