John Deere or Cummins

Discussion in 'Diesel Engines' started by islands50, Sep 1, 2014.

  1. islands50
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    islands50 Junior Member

    thinking of a troller repower, replacing the old 4-71 Detroit with either a John Deere 4045 and or the BT 4 Cummins, both have about the same HP ratting and speed in not the factor but GPH is, anyone have useful comparisons ???
     
  2. gonzo
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    gonzo Senior Member

    Google "fuel consumption map" for each and look at images. You can compare fuel consumption at different RPM's, torque ratings, etc.
     
  3. islands50
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    islands50 Junior Member

    Thank You Gonzo that was a help, although it did take more then just a quick internet search to get the basic information, the two engines are so similar in size, HP and toque curves one has to decide between, JD because of the wet liners or the Cummins with non replicable liners, with one you have a rather easy in frame rebuild the other would require much more work to remove the engine and bore the cylinders.
     
  4. gonzo
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    gonzo Senior Member

    With wet liners the engine will basically last forever, unless there is some catastrophic failure that causes major block damage.
     
  5. WestVanHan
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    WestVanHan Not a Senior Member

    Whatever you chose,either engine will give 20,000 hours plus with care.
    My cousin has a Dodge with over a million miles-never overhauled-though it is getting soft...so maybe 25k hours? Don't know.

    The Cummins have no sleeves but usually only require a hone. I am a bit leery of wet liners,they can leak.

    The win for Cummins IMO as parts are available almost anywhere in the world and are cheap...any Dodge dealer or auto parts store. JD-hard to find.
    Full rebuild kits with pistons/all bearings/all gaskets are about $600,turbo rebuild kits are $100.
    And you can get a totally reman 4BT for a few grand,brand new heads are $500 or so. JDs are quite a bit more.


    If you have the room,I'd suggest spending slightly more and getting the smoother 6BT.
     
  6. islands50
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    islands50 Junior Member

    West, the 6 would be nice and the extra power could be used, yet it would be more then the hull requires to archive hull speed, and or intended use, and it is fuel efficacy I am more interested in then raw power, this is a working boat not a pleasure cruiser
     
  7. d1970
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    d1970 Junior Member

    If the 4045 you are thinking of is the mechanical version,go for it.
    Though what is wrong with the detroit in the first place?
    If you are in it for fuel savings, get an estimate on the repower cost, then calculate how many hours later you will be in the green :)
     
  8. WestVanHan
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    WestVanHan Not a Senior Member

    You'll find a big difference in NVH as the DD 4 cylinder is really an 8 cylinder packaged as a 4...so twice as many power pulses per revolution.

    The mechanical 6BT have a continuous rating of about 115 hp so can be run at much less hp than that. Just think how the Dodge truck engines run for hundreds of thousands of miles at a small fraction of their peak hp.
     
  9. islands50
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    islands50 Junior Member

    The question was asked why not just redo the DD 4-71 well that is easy to answer, they can be painful to the ears, I have had them before and to be honest they are not my favorite engine, for more reason then just the sound, they leak oil, are getting to be very long in the tooth as in age, and parts, where with the Cummins BT I can get parts at the local parts store, the same can be said about the JD engine
     
  10. FAST FRED
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    FAST FRED Senior Member

    If you chose the JD , remember the inland JD folks sell factory rebuilt JD 2 or 3 times a year with NO core charge.

    Tha savings between farm and marine are incredible IF you can marinize the engine.

    Or far better , simply chose a keel cooler and dry stack , and use a stock engine.

    Twin Disc are available rebuilt if you want to keep costs down.
     
  11. islands50
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    islands50 Junior Member

    is there any other way to go ?? dry exhaust and a keel cooler, this is a work boat not a pleasure cruiser, was always my train to thought, less hull openings, fewer hoses, the list just goes on and on, and since I am in a costal Ag area JD parts are almost a dime a dozen.
     
  12. NavalSArtichoke
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    NavalSArtichoke Senior Member

    The Detroit is a 2-cycle motor, and those types are being replaced by 4-cycle designs because they can meet the lower emissions requirements. As others have pointed out, the Detroit was not designed to run quietly, and although it was a durable and popular motor in its day, the basic design is about 75 years old, and much improvement in diesel engine technology has occurred in that time. Parts for Detroits will be available for a while, but why chance it when newer engines with a lot of life are available?
     
  13. Mik the stick
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    Mik the stick Senior Member

    I like john Deere engine I attached a document on engines with power fuel consumption etc I hope it helps.
     

    Attached Files:

  14. FAST FRED
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    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    The brochure is the usual mfg info that is almost useless to setting up a vessel.

    What is needed is a FUEL MAP that shows where the engine is efficient and where it is not.

    Looks like a kids drawing of clouds , one in the center is the sweet spot , the best Hp/ fuel consumption. outside is the less efficient , and so on .

    With out this , its just Boob Bait for the Bubbas , as a US president used to say.

    >dry exhaust and a keel cooler, this is a work boat not a pleasure cruise<

    Most lobster boats and small -60 ft fish folks use keel coolers as they are far less maint than an extra seawater system to push water thru an internal heat exchanger.

    Most select dry stack as no sea water needs to be pumped into the exhaust.

    DS/KK is the simplest method , as well as low cost as no pile of specialized parts from a marine reseller need be purchased.
     

  15. islands50
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    islands50 Junior Member

    Want to thank every one that has added to this post, the fuel curves that I can see are very helpful and the information is well received, since both engines do have many options IE: turbo charging, after cooling, wet / dry exhaust, I suppose it all comes down to how much power is required to push this vessel at it's hull speed, and or most efficient speed.
     
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