New DIESEL outboard.

Discussion in 'Outboards' started by FAST FRED, Jun 24, 2015.

  1. Jamie Kennedy
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    Jamie Kennedy Senior Member

    It's not completely unreasonable, I don't think, but depend how you use the outboard you might be wearing out a lot of belts, and that could get expensive. Not sure how easy they would be to replace at sea either.
     
  2. Angélique
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    Angélique aka Angel (only by name)

    To my opinion the camshaft timing belts on car engines wear out fast, with an average replacement interval of about 100,000 km in cars I think . . :eek:

    Handy thing is you can buy a car with the same engine, so you'll need to stock only one set of spare parts . . . ;)
     
  3. Angélique
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    Angélique aka Angel (only by name)

    I just thought of that's the force on the top belt which is on the crankshaft, I like to know it for the lower belt, so we have to take the gear ratios in into account...

    [​IMG] - - - [​IMG]

    (render from post #8, specs from post #2)

    Do we have to multiply the above found forces by 66 for the max force on the lower belt . . :confused:

    P.S.

    That would give a max drive force of 488,400 N (for my understanding 49,803 kgf) on the lower belt and the shafts + bearings when the prop shaft pulley has a diameter of 100 mm, and 976,800 N (99,606 kgf) when the prop shaft pulley has a diameter of 50 mm . . :confused:
     
  4. Angélique
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    Angélique aka Angel (only by name)

    The OXE Diesel outboard has three shiftable gear ratios: 1:66 - 1:47 - 1:29

    But what do those OXE gear ratio numbers mean . . :confused:

    The below for example are gear ratios I can understand, from crankshaft to propshaft I suppose...

    Yamaha F 9.9: Gear Ratio (27:13) 2.08:1

    Yamaha T 9.9: Gear Ratio (38:13) 2.92:1

    - For both: Prop Shaft Horsepower 9.9 HP @ 5500 crankshaft rpm.

    - Same engine, different gear ratio, different prop.

    - Could be the
    ‘‘T’’ (High Thrust version) has the next size up leg, but if proportions in strength and size are OK it also could have the same leg as on the ‘‘F’’ except for the gear ratio. But since dry weight for the ‘‘T’’ is considerably higher as for the ‘‘F’’ my guess is the ‘‘T’’ has the next size up leg.

    - For the
    ‘‘T’’ the prop shaft torque rises with the same factor as the prop rpm drops compared to the ‘‘F’’. Hence the ‘‘T’’ version requires another prop (larger diameter and/or more blades and/or more pitch) which is adapted to the higher torque at the lowered prop rpm.

    This brings me to the next question: How much sense does the OXE three shiftable gear ratios make when there is only one non adjustable prop down below . . :confused:
     
    Last edited: Jun 30, 2015
  5. rasorinc
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    rasorinc Senior Member

    My guess on sales price is $32,000 to $38,000 US for 200 hp. What a deal......
     
  6. Mr Efficiency
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    Mr Efficiency Senior Member

    It makes sense to be able to go down a gear if the boat is heavily loaded, or conditions require speed to be backed off. You can be running the engine closer to its "happy" rpm range more of the time.
     
  7. Brian@BNE
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    Brian@BNE Senior Member

    So do these things heave a reverse gear?
     
  8. Mr Efficiency
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    Mr Efficiency Senior Member

    It would be astounding if it did not. Has to have it.
     
  9. SaltOntheBrain
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    SaltOntheBrain Senior Member

    Regarding reverse...
    It looks like the gears in the pic provide reverse.
    The dog engages the rear side of the gear for forward, the front
    (which counter-rotates the gear beside it) for reverse.
    Maybe.
    LF
     
  10. SaltOntheBrain
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    SaltOntheBrain Senior Member

    If they really want diesel outboards to be viable, they need to figure out how to control the power of a "runaway".
    Remember those from the days of naturally aspirated diesels?
    Running out of fuel and sucking air....using a fraction of the fuel normally required to idle...and suddenly your '84 diesel Jetta is burning rubber up a steep hill with your foot off the gas and both feet on the brake.
    Yeah, there's that kind of power in diesel.
    So...smaller engines, tiny injectors/injector pumps (less parasitic drag), no turbos, no inter/aftercoolers.
    My kids are grown and I'm starting to have time and money to play with things like this, so if somebody doesn't figure it out first, maybe I will.
    Then we'll be sitting here laughing about the days when people had gasoline outboards.
    LF
     
  11. philSweet
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    philSweet Senior Member

    belts 101.

    1. The tension in the belt where it leaves the driver is the same as the tension where it enters the driven pulley. And vice versa.

    2. The torque is the diameter times the difference in the tension of the belt from one side to the other.

    3. The tension can't be less than zero.

    4. Centrifugal forces in high speed belts increase belt tension and change the bearing loads.

    5. Belts have to be a little bit stretchy. Getting the modulus as high as possible is not the goal. Getting it just right is the goal. This results in a certain pretension requirement for a given setup. The spec will usually be between 10% and 20% of the tension under load for a 180 degree wrap.


    If you take a number like the OB leg accounts for 30% of the total hull drag, then there is a lot to trade off between drag reduction and transmission efficiency and still come out ahead. If you were pushing a barge and the OB leg was 2% of the total drag, belts might not look as good. But there is a lot to like about the arrangement if weight doesn't matter much. Particularly that the cylinders aren't on their sides and the reduction gears can be bigger, more efficient, and up in the power head. A four banger diesel needs much stouter gears than a six cylinder gas motor of equal power, so it is a challenge just to make the leg the same size as the gas job, let alone make it smaller.
     
  12. FAST FRED
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    FAST FRED Senior Member

    A "runaway" diesel is one that is so old with so many hours that it begins to consume its lubrication oil past the rings.

    Rare indeed , but the more common problem of a stuck injector causing a stuck rack (DD) and an engine that could not be shut down caused DD to insert a flap in the intake , operated with a button or cable in transit applications.

    This shuts down the engine very well.

    With the air police deciding on most engine specs , most will have electric controlled injection .

    The chances of a carb engine converion lasting long enough to run on its own lube oil is very remote.

    It took 25,000, 30,000 + hours on pumps or gen sets , and then the compression was so low it would take a can of ether to get it going , so there was no surprise.
     
  13. brian eiland
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    brian eiland Senior Member

    Chain Belt Drive

    My guess is they will end up using a 'silent chain' arrangement. This is a subject that has interested me for years. If you googled my name & belt drive, or chain drive, you would likely come up with a good number of hits. Regrettably there was a nice long subject thread on this subject over on Yacht forums, but when they made some recent software changes it got omitted.



     
  14. brian eiland
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    brian eiland Senior Member

    .....from that same discussion on this forum
    http://www.boatdesign.net/forums/newreply.php?do=newreply&p=453139


    Couple of more postings of interest
    http://www.boatdesign.net/forums/inboards/belt-drive-37290-3.html#post453264...with photos of PYI's system

    Slient Chain FAQ's
     

  15. brian eiland
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    brian eiland Senior Member

    Attached Files:

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