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Classic (Fairbanks Morse or old Deutz) vs New Diesel Mains

Discussion in 'Technical Discussion' started by TeKeela, Dec 18, 2014.

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  1. TeKeela, Dec 18, 2014
    #1
    TeKeela

    TeKeela Member

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    Hypothetical...

    Take a Fairbanks Morse in the 650hp range made in the 60's vs an equivalent say Caterpillar. I assume those engines were slow turning and continuous duty. So compare an equivalent Cat, maybe a C-18 continuous.

    1. would the newer engine be more fuel efficient?
    2. would you be able to find parts for the older?
    3. would you need a heavy parts schedule for the older as it is slow turning, thing has worked for 50years.
    4. significant size difference between the two, assuming a C-18 to compare.
    5. if it was in a boat and working, would you want to swap it for reliability?

    Out with the old and in with the new, or keep the classic, it's experienced and trouble free?
  2. bernd1972, Dec 18, 2014
    #2
    bernd1972

    bernd1972 Senior Member

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    If replacing such an old beast I´d rather take the 13,5Liter Deere than a CAT...
  3. TeKeela, Dec 18, 2014
    #3
    TeKeela

    TeKeela Member

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    ok, why? serviceability? cost to operate? fuel consumption?
  4. TeKeela, Dec 18, 2014
    #4
    TeKeela

    TeKeela Member

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    And the old engine would be a slow turning in the 750rpm range so I'm assuming it was naturally aspirated?
  5. bernd1972, Dec 21, 2014
    #5
    bernd1972

    bernd1972 Senior Member

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    The Deeres are probably among the most durable and reliable engines on the market and even some serious bit cheaper than compareable CATs.
  6. TeKeela, Dec 23, 2014
    #6
    TeKeela

    TeKeela Member

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    I know Deeres are very popular in commercial applications. However the model referenced above is turbo charged high speed. At the point the turbos kick in, the fuel consumption increases dramatically. I'm trying to get into my head, if space is not an issue, would a bigger older non-turbo slow turning engine be better fuelwise than a newer turbo high speed replacement? Aside from a smaller package for the same horsepower, what do you gain with a modern high speed diesel compared to a slow speed classic?
  7. Capt J, Dec 23, 2014
    #7
    Capt J

    Capt J Senior Member

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    Well that totally depends on the boat and it's operation. If you can give us that, boat/size/cruising speed/hull type......it would help a lot.
  8. TeKeela, Dec 24, 2014
    #8
    TeKeela

    TeKeela Member

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    It is a commercial boat 50m x 10m x 3m with a pair of fairbanks that seem to be 750hp and about the same rpm. The specs were 34gph at 9-10kts cruise including one generator. I was just thinking about old vs new and that seems to me awfully good fuel consumption for moving something of that size. But since the engines are so old, could consumption be further reduced with modern technology.

    I love the idea of conversions over a new build. Not in my future at the moment but I do like to crunch the numbers.
  9. Capt J, Dec 24, 2014
    #9
    Capt J

    Capt J Senior Member

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    I think you're probably not going to get better fuel economy with new diesels, most likely worse. I would think you're going to need de-rated 12 cylinder CATs like the 3508 series just to have the torque to move a boat that size. I don't think C18's would be a good fit. Parts will be easier to come by and reliability may be better. I don't know.
  10. K1W1, Dec 24, 2014
    #10
    K1W1

    K1W1 Senior Member

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    Here we go again, How can a 3508 be a 12 cylinder engine?
  11. leeky, Dec 24, 2014
    #11
    leeky

    leeky Senior Member

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    Be careful there, K1W1. Capt J might accuse you of SPLITTING HAIRS.:p
  12. Capt J, Dec 24, 2014
    #12
    Capt J

    Capt J Senior Member

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    Woops........it's a very large displacement 8 cylinder....... However the C18, isn't that large of displacement 6 cylinder.

    Aside from calling me out on my clerical mistake. Kiwi, what is your recommendation for this man and his yacht?
  13. Capt J, Dec 24, 2014
    #13
    Capt J

    Capt J Senior Member

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  14. TeKeela, Dec 24, 2014
    #14
    TeKeela

    TeKeela Member

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    To clarify, it is not my yacht, but I do wonder about converting a commercial boat. I'd like to do that one day and I enjoy figuring out the old vs the new, what would stay and what would go. Fuel consumption is no more than a 60' convertible and you can bring a lot more toys and tow the convertible.
  15. TeKeela, Dec 24, 2014
    #15
    TeKeela

    TeKeela Member

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    There is no replacement for displacement.