EFI low milage 2-stroke DD

Discussion in 'Diesel Engines' started by StianM, Nov 4, 2012.

  1. StianM
    Joined: May 2006
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    StianM Senior Member

    One of my weird fantasies are comming back to me.

    Thinking about repowering a boat with a 6V53 DD.
    Allways thought that the blower is sucking too much power from the crank and would like to trow it away.
    Only problem is to savange the cylinders on low load when the turbos are not making any boost.

    One plan has been to use 3 turbos.
    Have two turbos that are large enough to supply the engine at 50% and set them up sequential so that all the exhaust gas would run trough one of them on low load.
    All the exhaust leaving the two turbos could then go to a single large one that feed the two smaller ones with enough air for rated power.
    [​IMG]

    I also doubt that this would be enough and a jet asist system to reduce turbolag and help the turbos on startup and low load is things I have concidered. Jet asist is a system used by larger diesels where compressed air is injected to the compressorwheel on the turbo to not only inject air, but help it spool.

    I think on of the final puzles came to me today trough a aftermarket ECU for diesels.
    http://narwhalmotors.com/
    Now ther is posebiletys if the ECU can be programed to inject a second dosage of fuel quite late in the combustioncycle producing more energy for the turbo to spool. It could be done by introducing a PID regulator to the boost presure increasing the quantety of fuel injected late on if the boost is below a certain level.

    I know this methods would work, but how well is the question.
    If I can not force enough air trough the engine on low RPM/load it will not run and it will strugle to start.

    Has anyone ever atemted to run a DD without blower?
     
  2. gonzo
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    gonzo Senior Member

    This are the specs for the new style 6V53. I can't see your complicated system being any better. Also, turbos don't work until they spool up. That means the low end torque is not good.
    http://www.army-guide.com/eng/product160.html
     
  3. StianM
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    StianM Senior Member

    The specs for the new 6V53 are sweet and ******* hard to get by atleast in europe. I have no idea who to blow to even be able to touch one without selling a kidney.
    My system would be bether regarding efficensy, but not something the army would rely on since a start faliure could cost lifes.

    For the problem about the turbos it's the problem I have described solved with running this turbo setup combined with electronic injection and maybe a jetasist system.

    I have not put up calculations for this and my matematics are rusty so I would need to dig deep in my old schoolwork to see if it's even posible to get the boost on low load without serious smoking.
     
  4. powerabout
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    powerabout Senior Member

    Bill Barry-Cotter from OZ raced a pair of v892? detroits that had some clever blower cutout and turbos and made a huge amounts of power, Class1 banned it.
    Now add a high pressure fuel system computer controlled to that engine and it will be a new life for old detroits
     
  5. FAST FRED
    Joined: Oct 2002
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    FAST FRED Senior Member

    How about just using a DD series 50?

    You can set the power required with the D Dec and by injector selection.

    The turbo can be sized to power at the cruise RPM.
     
  6. parkland
    Joined: Jul 2012
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    parkland Senior Member


    Instead of removing the blower, why not have a bypass to reduce parasitic losses?
    Superchargers (the old style) had the same issue, they were wasting power unless you were actually using all the air they were compressing.

    New style superchargers have an air release or bypass thing (I don't know too much about them...), so that they don't waste too much power at all.

    I would guess that would be the best easiest thing to look into.

    As far as the custom ECU, they are great if you are a computer programmer or know someone. I am a little bit of a computer programmer, and I would take using one as a major project.
     
  7. FAST FRED
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    FAST FRED Senior Member

    The Blower on any DD is required to push air thru the cylinder to empty the exhaust gasses.

    Since the fuel is not injected till after the cylinder closes , there is not the inefficiency of fuel pushed out in the exhaust like most 2 stroke gas engines.(Exception split singles).

    A huge advantage for the rec. boat owner is the ability to remove an air box cover , and spray in preserving oil when the engine is not being used.

    If the gasket is new and access easy its only a couple of min to stop the cylinder walls from rusting.
     
  8. powerabout
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    powerabout Senior Member

    they also need variable exhaust valve timing

    Just remember the BRP injection on the 2 stroke outboard made them produce 40% less CO than a 4 stroke in the mid range, only do that with a computer.
    The GM has the bonus of exhaust valves so you have the ability to have control of the timing

    PS Volvos have had blowers and turbos for years ( not that I'm any fan fo the green death)
    Gear driven turbo chargers have also been around used in various ways
     
  9. Frosty

    Frosty Previous Member

    I'lle need my fishing waders to visit this thread next time --its knee deep here.
     
  10. powerabout
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    powerabout Senior Member

  11. StianM
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    StianM Senior Member

    I did see that the later models from DD used this, but still there would be some losses and I suspect that removing the blower would also reduce the weight alot.

    A turbo would do the same job. Only the turbo would not work on low RPM.
    A turbo is not working on the energy from exhaust being pushed out. It's running on the energy being produced in the cylinder and without a engine it would more or less work like a gasturbine.


    Good to see others are playing around with improving the old diesels. If there work pay off replacing old worn parts with this ones might pay off for us to use it, but I don't think it will be a option to replace working parts with this ones.
     
  12. Redtick
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    Redtick Junior Member

    A two stroke DD will not start and run without the blower turning or compressed air fed into the air box.

    It will try to start but fail to run. Pull the drive shaft from the gear drive to blower drive to test.

    If it is a factory turbo engine, the blower is under driven already.
     
  13. StianM
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    StianM Senior Member

    Here I have to arest you with facts.
    New EMD diesels don't use blowers, but use a clutch on the turbo so it's only clutched in during low load and on high it's running off exhaust gasses only.
    Same layout as a DD.

    Sulzer and B&W use a electric blower witch they run only on low load and during startup. once on load only the turbo is running.

    If you do like thet the blower will still be there, but not spinning so it will be the same as if you blocked the inlet. Not a good comparison.
     

  14. powerabout
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    powerabout Senior Member

    they will fire usually once per cylinder
    had that when the quil shaft has snapped
     
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