Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

HHO Water4Gas Increase Mileage

  1. Mar 14, 2010 #1
    my uncle has been watching the videos on youtube with all of the people who supposedly gained gas mileage by installing a water electrolizer on their car and running the gases emitted into the intake. now ive tried telling him about the conservation of energy law and how that little bit of HHO gas isnt going to make a difference because the MAF sensor on his car will still tell the ecu to inject just as much gas as it always does, however he believes that because there is such a hype on the internet there has to be some truth to the tale. i cant think of a good explanation of why they get "better" gas mileage other than placebo effect and less aggressive driving but i could be missing something.

    does anyone know of these systems and is there any truth to the claim? i am very interested and if it is true i would like to know how it works and want to try it to my car.
  2. jcsd
  3. Mar 14, 2010 #2


    User Avatar

    Staff: Mentor

    The ones you see on youtube that claim massive increases (I've heard like 40%) are either hoaxes or just errors.

    However, it is theoretically possible to use hydrogen to improve the combustion efficiency and burn rate by a few percent to get an overall gain of a few percent, if your hydrogen generator is efficient. I can't imagine this could be done by an individual without specialized skills and access to the car's computer to alter the fuel/air mixture.

    We have a bunch of threads on the subject you can do a search for, including some with a NASA study on the subject that investigated the combustion improvements I mentioned above.
  4. Mar 14, 2010 #3


    User Avatar
    Science Advisor

    Hoax. Scam. Avoid.

    I looked into these a while back and found (unsurprisingly) that their claims are completely unsubstantiated, and the "science" posted in support of them either makes little or no sense, or else it is unrelated to what happens inside an engine.
  5. Mar 15, 2010 #4
    So did I and thought the same untill I realised there must be some gain when the vehicle breaks, though there is usualy no reference to this effect.
    To explain the alternator must act as KERS device when you break.
    If you have a HHO device fitted.
    So any gas produced will be a bonus which would have gone to waste as heat.
  6. Mar 15, 2010 #5


    User Avatar
    Science Advisor

    I think you mean "when the vehicle brakes" rather than "breaks"!
  7. Mar 15, 2010 #6


    User Avatar
    Science Advisor

    Buckley, if a vehicle has a KE recovery alternator system then it would normally charge the battery when braking, so as to reduce the amount of alternator power required during normal driving. This electrical energy is needed to run the ignition and other electrical systems in the car, if you divert it to make HHO then you only have to take more power from the alternator during regular driving. So I fail to see your point.
  8. Mar 15, 2010 #7
  9. Mar 15, 2010 #8
    There is a surplus of energy that goes to waste when brakeing.
    So much, that a seperate alternator could be added to the vehicle that would power a HHO device when brakeing.
    The amount of electrical energy needed to run the car is minimal compared to the amount of energy wasted when brakeing which could be recovered and stored.
  10. Mar 15, 2010 #9


    User Avatar
    Science Advisor
    Homework Helper

    A chemical regenerative braking systems is possible but hardly the most effective.
    You would need a huge alternator to sink anything like the 200Hp energy dump when braking, you need to carry a fresh water source tank, then you have to store a pressurized mix of H2/O2.

    A flywheel or a battery would seem like a better bet.

    Or you could use an adiabatic expansion gas system linked to a cybernetic control unit with optical inputs - also known as taking your foot of the gas when you see red lights ahead.
  11. Mar 15, 2010 #10
    Wouldn't the hydrogen use up oxygen in the charge that is needed to combust gasoline faster than the gasoline? I think it makes sense to use oxygen in the heat engine to increase delta T and use hydrogen post combustion in another stage along with more fresh air in conjunction with catalyzed exhaust air. Feed it into a thermoelectric generator and, along with regenerative braking, increase efficiency?
    Aside from the theory here it would be interesting if it is economical to build, run, and repair this system type. Hybrids seem to have a favorable cost-benefit ratio AFAIK. And from that perspective, tax the hell out of non-commercial trucks and rear wheel drive vehicles! (http://en.wikipedia.org/wiki/File:Energy_flows_in_car.svg)
    Now after typing all this I haven't accounted for the energy needed to split the water molecule :-/ . I think the most beneficial advances are going to be in material sciences in tires and lubricants.
  12. Mar 15, 2010 #11
    Yes I can see you points.
    There could be some advantages though.
    I don't imagine a large pressurized tank would be needed to store the mix as long as the fuel was burnt as quickly as possible after it was produced.
    Only a small tank would be needed if the water produced after combustion was recovered,
    The weight of the alternator would be comparable to flywheel or battery.You might get better storage from a HHO device in as much that more recovered energy could be used more efficiently.
    There is nothing more annoying than watching your flywheel run down after you have stoped.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook