Water Ingestion Into I/o Merc Engine

Discussion in 'Powerboats' started by Boatwiser, Sep 22, 2015.

  1. tom kane
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    tom kane Senior Member

    The story of Jim Wynne and his development of his invention is very interesting
    and the number of the problems he had to overcome were many but did he solve them all. there are always more bugs to sort out.
     

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  2. gonzo
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    gonzo Senior Member

    Why are you posting a photo of a water cooled exhaust installation?
     
  3. tom kane
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    tom kane Senior Member

    It does not inspire confidence in me when someone tries to justify pumping a corrosive fluid (sea water)
    to cool a motor and pump it into an exhaust which does not do an effective cooling effect anyway.As always Marine Industries lacks the advances of the auto industries in many areas especially in sensible cooling and noise abatement.Many people do benefit from closed water cooling in boats and water jacketed exhaust systems.
     
  4. gonzo
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    gonzo Senior Member

    You must be living under a rock. Modern marine engines are very quiet and have no cooling problem at all.
     
  5. Ike
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    Ike Senior Member

    And now that the EPA has gotten into the act requiring catalytic converters and setting exhaust emission limits the industry has had to step up and make exhaust systems even better. Water ingestion was a huge issue when developing the standards for catalytic converters because any water will kill a catalytic converter. (and they aren't cheap) Since they are installed jut downstream of the riser, right where the water is injected into the exhaust, it becomes a huge design issue
     
  6. PAR
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    PAR Yacht Designer/Builder

    As I have been hinting at all along, some engine drive combos have seen some teething problems, with the latest round of requirements (and other issues), but these have/are being sorted out. You can buy into the histeria of some, or you can simply take the proven steps that have solved other's concerns. These sort of "adjustments" are continuous in the industry and those that regularly deal with them, know the real story, while those that simply speculate, without looking at the figures and actual incident reports, are the arm chair quarterbacks, that always seem quite knowledgeable the day after the game.
     
  7. BMcF
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    BMcF Senior Member

    That ^.
     
  8. BMcF
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    BMcF Senior Member

    That too ^.

    The fresh-water-cooled Chrysler 318s in my 1974 32' Marinette are the original engines and are in perfect condition. I've replaced the risers/elbows once ($800 total?) and both of the Sendure heat exchangers once ($2000 total).

    $2800 in "heavy maintenance" in 41 years of exclusively salt-water operation. $68 a year. (several water pump and/or impeller changes along the way, of course...)

    Woo hoo. ;)
     
  9. tom kane
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    tom kane Senior Member

    Just love those fresh water cooled boat motor, I don`t know why any experienced boatie would not know that that water jacketed manifolds exhaust and mufflers are anything but cool.
     

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  10. PAR
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    PAR Yacht Designer/Builder

    I'm not sure who's artwork you keep posting Tom, but they're wrong in terms of hot gases creeping along above the water flow, both in the jackets and exhaust tubing. Maybe a little research into how these systems actual work might be in order. I've done a lot of exhaust work over the years, both dry and wet and the stuff you keep posting, flies in the face of reality and actuality. It's one thing to have an opinion, maybe based on some bad experiences, but another to postulate ridiculousness that can't be supported, either statistically or from an engineering point of view. You don't really think the water simply flows like a mini river at the bottom of the pipes do you?
     
  11. tom kane
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    tom kane Senior Member

    Don`t get upset par, or there may be danger of having the thread closed. perhaps you should review some of your ideas and check that what you are saying is really spot on
    and let others have an opinion and discuss what they are doing with out insisting that you have all of the ducks in a row.
    Water in a jacked manifold does flow like water in a stream as gravity makes it go to the lowest parts, the water is not all vaporized into the exhaust gasses just some of it and that is what gets pulsed back and forth with the changes of pressures and it can get into the motor thus the reason not to inject water into the exhaust.
    Many trades people have spent their life thinking they know how things work but when it comes to real facts many fall short.
     

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    Last edited: Sep 28, 2015
  12. PAR
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    PAR Yacht Designer/Builder

    No water in the pipe is a flowing liquid; it is in two basic states, atomized or highly aerated. Very little of the water is flowing like a liquid and yes, I've done countless hours of flow bench testing in regard to flow dynamics inside intakes, heads and exhaust pipes. It's not a matter of getting upset, but stating the facts, which your little cartoons clearly aren't showing. The text that accompanies these way to small to see very well images, just simply isn't accurate.

    Ambient temperature water, touching a 1,200 degree pipe doesn't stay liquid for long (fractions of a second). As the pipe and exhaust flow cools, water does slow it's activity, dropping from an atomized state to a highly aerated one. Only at the very outlet, where pressure drops to atmospheric, does the water actually flow sort of like a liquid again and looking at any wet exhaust outlet as a boat idles, will bare this out. It doesn't flow out like a garden hose, but in fact is blown out in large, highly energized drops, which is nothing like water flowing and in fact this trait is intentional, as it dramatically increases surface area for heat transfer. Flowing water would be much less effective, in this regard.

    I'm not sure what the last image you've posted is, but it's clearly not an exhaust exit. The water coming out of that pipe isn't energized, it's just running down hill. Simply put, the dynamics of this are well known and well understood, but you concerns can't be backed up with rational debate, at least thus far.

    Water vapor doesn't get "pulsed" back into the chambers (usually), though with recent engine changes, some cam profiles do need to be more "marinized" as the duration and overlap on these are too "fat" (automotive style), which causes a poorly setup manifold to suck some vapor, under certain load conditions. This isn't a flaw of the system type, but an error in cam lobe shapes and timing demands, as well as (more importantly) manifold arrangement. Again and as the recent service bulletins have recommended, solutions are available, without condemning the entire arrangement, in favor of one that can't be legally employed on any production boat, in the configuration or the OP's. Suggesting the contrary is blatant misrepresentation and this is what has me perturbed.
     
  13. tom kane
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    tom kane Senior Member

    There are lots of imagines of water exiting boat exhausts and of course the more energy behind the flow breaks it up more.
    Many boats go slow most of the time so the water flow changes.
     

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  14. powerabout
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    powerabout Senior Member

    Tom, are you confusing what happens in the water injected exhaust system versus what happens in the jacketed manifold?
    On a heat exchanged engine, one is fresh and one is raw water.
     

  15. PAR
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    PAR Yacht Designer/Builder

    Again Tom, more who knows what's going on images? So where's the water coming from those obviously trailer borne boats?
     
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