GM Detroit 450hk with Allison gear

Discussion in 'Diesel Engines' started by StianM, Dec 25, 2008.

  1. StianM
    Joined: May 2006
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    Location: Norway

    StianM Senior Member

    After the late financial crises I have been starting to look around for a cheap boat from a poor bankrupt *******.
    I have found a few victims and also found a few diesels I would like to put my hands on and one of this is two detroit's with turbos from 1987.

    This are two strokes and I guess that they are quite uneconomical since they would nead to run a savaging pump (blowers) to supply the engines with air and low load and at startup.

    I was thinking to simply trow off the blower and get some electrical superchargers from e-bay to savenge the engine at startup and fit a smal turbo to get boost from low load/rpm and a large one to keep up at high load/rpm making it a two stage system.

    To be able to respond to load changes at low loads I was thinking to use a jet assist system controlled by a Logo PLC.

    I have a smal turbo from a car around so adding it would not require additional cost, only additional work.

    To make a jet assist system would require some fabrication and a compressor and airbotle would give me work air onboard so it would serve a second benefitt.

    Probartly some will say this is a bad idea, but I really LOVE!! two strokes.
    And I get two for about 20 000USD witch ower here is concidered cheap.
     
  2. FAST FRED
    Joined: Oct 2002
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    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    The blowers are necessary and will probably absorb less power gear driven , stock ,than other method.They scavenge the engine (push the old air outof the cylinder ) at ALL speeds.

    Those old DD's will crank 16hp per gal and 18 with turbos if properly loaded.

    The hassle is at less than 60% rated power , they become very fuelish.

    So don't worry a bit if you will be running them hard , there hard to beat for long life.

    DO remove and replace them if all you really need is a few HP for a displacement cruise.

    FF
     
  3. StianM
    Joined: May 2006
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    Location: Norway

    StianM Senior Member

    If you take a look at sulzer or B&W two strokes you will see they don't use a blower.
    They only use a external powered blower at startup and low load.

    At high load the engine is scavenged by turbo only witch is the best way for economical use.
    I have recently seen use of jet assist systems on generators witch was not able to keep 60Hz when having quick changes in load while running in load conditions under 60% witch is why I thought this could be a good idea for a two stroke.
     
  4. FAST FRED
    Joined: Oct 2002
    Posts: 4,519
    Likes: 109, Points: 63, Legacy Rep: 1009
    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    The drilled holes in the cylinder walls are not very large , so a good push on the exhaust is needed at every rpm.

    The Roots blower is not bad at its job although it heats the air a good deal.

    An intercooler is a help.

    18hp /gal is as good as it gets with out an electrical injected complex nightmare and 30,000psi for injection.

    AS is you have the product of 50 years of improvements , good luck in improving on it with out thousands of dynomometer test stand hours.

    There are hundreds of ways to "improve " any vessel, why gamble on a method . before at least doing the first dozen or so that WILL be sure help?

    FF
     
  5. StianM
    Joined: May 2006
    Posts: 593
    Likes: 23, Points: 18, Legacy Rep: 114
    Location: Norway

    StianM Senior Member

    I will get two of this engines with gear for about 10 000USD where one of the engines is missing a turbo.
    I concider this to be cheap compared to a penta, but are they worth it?

    I was thinking to put one of them in a 30ft bayliner and have the second as spare.

    I still think it would be a good idea to remove the mecanical blower like sulzer and B&W has done on there two strokes. The turbocharger would have no problem pushing the exhaust out when on full load, the problem would occour on low load where the savange preshure is not high enough to push the exhaust out.
     
  6. FAST FRED
    Joined: Oct 2002
    Posts: 4,519
    Likes: 109, Points: 63, Legacy Rep: 1009
    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    "I was thinking to put one of them in a 30ft bayliner and have the second as spare."

    Check the 12V 71 weight ,with tranny, before sinking that toy.

    FF
     

  7. StianM
    Joined: May 2006
    Posts: 593
    Likes: 23, Points: 18, Legacy Rep: 114
    Location: Norway

    StianM Senior Member

    12V 71??????????? this is a V6.
    It's about 1000kg witch is twice a KAD41.
    One of this diesels should do about the same job as two pentas.
     
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