Getting extra torque from your boat motor.

Discussion in 'DIY Marinizing' started by tom kane, Jul 19, 2016.

  1. PAR
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    PAR Yacht Designer/Builder

    Agreed, all this paranoia about things that just don't happen that much any more. Yes, once it was pretty common, but reasonable regulations have slowly been incorporated and boats just don't blow up any more. The statistics are easy to find and easy to understand.

    Lastly hanging tanks on the outside of a boat sounds like a great way to increase boats blowing up. Boat sides take a beating in everyday use, if not explosions, lots of contaminated waterways from the resulting leaks.

    Again, well maintained boats don't blow up and those that do, can usually have the fault traced back to shoddy repairs or maintenance. No system can eliminated a boneheaded owner from the equation.
     
  2. tom kane
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    tom kane Senior Member

    Boat designers should be able to read and intemperate a customers List of Requirements much better than some have read previous posts as no one has suggested hanging things over the sides of boats.
    Just providing a customer with the bare requirements of the Regulations may not be enough for some people especially a safe family boat.

    Copying previous boat design of other designers is not designing but but new innovative ideas and offering new solutions to make a better product is, and not expecting some slow moving Regulatory bodies to tell them what to do.
     
  3. powerabout
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    powerabout Senior Member

    Tom
    the Abyc and the uscg are all ears if you want to show safety improvements through design.
    There are people on here and other sites that are advisors to them.
     
  4. mydauphin
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    mydauphin Senior Member

    To me greatest improvementioned in boat safety for small boats has come in with the wide spread use of outboard motor. Less chances for all kinds of issues.
     
  5. FAST FRED
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    FAST FRED Senior Member

    "Copying previous boat design of other designers is not designing but but new innovative ideas and offering new solutions to make a better product is"

    True Dat , but after 100 years gets harder to actually find some ideas that are not 75 years old.

    Ricardo is still DA Book for gas engine design , look when it was first published.
     
  6. tom kane
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    tom kane Senior Member

    They may well be all "ears" but is there anything between.

    Do you represent any of those Institutions.???
    This is a great boating forum that anyone can tune in to and comment on the experiences of other people. Hopefully reasonably well thought through.

    I have had a lot of experience of many Institutions and clubs voluntary, and pressure groups. And crazed activists.
     
  7. tom kane
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    tom kane Senior Member

    getting extra torque from your motor

    Perhaps we should prohibit installing a motor inside the hull of a boat unless they are in in a separate compartment that is sealed from the inside of the hull and drained and ventilated outboard, including the fuel tanks.

    Hanging something even an outboard over the side of a boat has a lot of disadvantages as has been pointed out in some posts.
     
  8. mydauphin
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    mydauphin Senior Member

    When I was original specs for boat that I built and look at putting engines in pods that could removed or swap out rather easily. Each pod would have been self contained and separate from boat and each other. But ultimately idea was impractical due to size of diesel engines. So opted instead for twin engines within a separate firewall ed engine compartment.
     
  9. tom kane
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    tom kane Senior Member

    getting extra torque from your motor

    I don`t think you can be phobic about safety if you can easily make it safer why not.

    I spent time training on United States M3 Light tanks and when you started one of them up you had to have the engine compartment doors open and some one standing ready with a fire extinguisher because if it backfired it burst into flames. They ran on high octane fuel.
    That does not give you a lot of confidence even though they were very fast so you could make a hasty retreat.
     

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  10. tom kane
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    tom kane Senior Member

    getting extra torque from your motor

    Image shows one way EFI fuel systems have evolved and using a similar system incorporating the principle of isolating your fuel from the inside of the hull you can make a safer fuel system for power boats.
     

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  11. Barry
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    Barry Senior Member

    Tom you have introduced three distinct topics for discussion
    1) long induction tubes
    2) ram tubes
    3) fuel components external to the interior of the hull

    some comments for the long induction tubes
    1) and for long, I am guessing that with an 8 foot beam, your induction tube would be around 3-4 feet, this would deliver slower starting and provide a nice combustible tube of air/fuel mixture. When you turn the engine off, this mixture will vent back outside the carb and some fuel may coalesce back onto the surfaces of the tube, hardly safe from my point of view. Longer induction tubes can provide a better evaporated mixture for introduction into the cylinder. If longer induction tubes provided a significant improvement in fuel efficiency all the automakers with millions of dollars of research and development available would have included them in all cars in the market for the hunt for lower fuel consumption. But they do not.

    2) Ram tubes, at least by my definition are tubes that some portion face the direction of travel of the boat/vehicle and provide an increase in pressure to help fill the cylinder on intake. But how much of a difference can they make?
    The numbers show that if you have a forward facing tube at 30 miles per hour the dynamic pressure increases by .016 psi. Compared to atmospheric pressure of 14.7ps, this is hardly significant.
    Your comment that with ram air tubes you can increase volumetric over 100%. I would doubt this with the low pressure increase shown above. Volumetric efficiency is much more affected by the overlap of intake and exhaust valves, pressure losses due to turbulence etc than a slight increase in air pressure. In fact I would say that it would be almost impossible to attain a 100% volumetric efficiency as there will be a less than atmospheric static pressure in the plenum/intake tube when the cylinder is moving down on intake and hence you will not be able to get a full volume of air into this area, ie pressure below atmospheric lets just call this vacuum, ie negative PSI guage means that there is less molecules of air in the chamber. So you cannot attain 100% volumetric efficiency
    The only way that you could obtain a 100% volumetric efficiency is if the plenum pressure is above atmospheric pressure. Think turbo or super charger.

    Certainly superchargers and turbos can make this happen but I doubt there are any that operate at the .016 psi at 30 mph numbers shown above

    I could not see your carb configuration clearly in your picture but if the direction of the carb throat is at 90 degrees to the direction of travel, you will have effectively reduced the pressure in the throat rather than increase it

    The ram air, hood scoop, cowl induction systems from the 70's were designed to provide cooler denser air to the carb as compared to taking warm air from behind the radiator heat exchanger.

    Regarding a comment that a turbo can provide low rpm boost in pressure/performance. Certainly they can but as they ramp up speed, and pressure, you would have to dump the excess pressure off so as not to create a pre-detonation problem in the cylinder on compression

    Volvo D6 diesels use a supercharger for the low end boost and a turbo for higher rpm, giving stronger acceleration until the turbo can create its own pressure
     

  12. tom kane
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    tom kane Senior Member

    Thank`s for your comments Barry.
    My comments on long induction tubes (which are ram tubes) are based on my experience not theory and using them in my boats giving me peace of mind, and experience working in a Chrysler Service workshop talking to fussy customers running Chrysler engineering and other makes and models.

    We found that technology very suitable for that time in motoring with no problems with safety or economy and performance or fumes from carburetors

    You may not have grasped the concept of isolating all parts of a boat fuel system from causing problems in side the hull of a boat.
    You may have also missed the point that standard induction on motors with EFI can be worked similarly.

    I did not comment on Volvo D6 diesels but others may have.

    If you are presented with an idea don`t take for granted that is the only way to do it but make your own improvements according to your own theories.
     
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