Gas Powered DEs

Discussion in 'Downeast Engine Room' started by BillD, Aug 10, 2013.

  1. Kodiakan

    Kodiakan Senior Member

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    While I've not read every post, I haven't seen anyone speak to reliability. What are your experiences with gassers and diesels?
     
  2. SemperFishBoston

    SemperFishBoston Senior Member

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    AJ26 Duffy
    I found this to be a great old thread as a gas powered DE guy. Thought I would surface this one again.

    26’ Duffy
    Original MarinePower 350 (325hp according to builder) 2500 hrs
    3.5kt @ 600 rpm
    10kt @ 2200 rpm
    16kt @ 3000 rpm
    17.5 @ 3200 rpm (cruise)
    19kt @ 3600 rpm (wot)

    Zf63a 2.04:1 gear
    19x18 4 blade prop

    Engine tops out at 3600 rpm even though it’s a 4500 motor.

    Steve
     
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  3. Sobie2

    Sobie2 Member

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    SemperFishBoston,

    I have had three Uniflite boats all with v8s. One Buick V8 (23'), another with a single 454 (27'), and the last (31') first had twin Chrysler 440s, and then twin Mercruiser 5.7s. Cruise was best for all around 3,000 rpms for longevity and speed, and fuel economy. only one ever got to 4400 rpms WOT.

    Stick with what you got, maybe try a Michigan DJX three blade (first) or DQX four blade.

    I would think you probably won't get much more out of the hull, but maybe raise your 3000-3200 rpm cruise speed.

    Also throw any junk off the boat as weight is the enemy.

    Sobie2
     
    Last edited: Mar 8, 2018
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  4. Nighthawk

    Nighthawk Senior Member

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    Location:
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    Carolina Classic
    I would add that the big blocks are no longer made. There is a pretty good market for rebuilt big blocks but if you want new the 6.0 GM is what is left standing. Although a very good engine, it is high revving and less torque producing especially down low than the big blocks it replaces.

    Friend had a 29 Dyer with a 454/350hp for years. It was a good match for that boat.
     
  5. F/V First Team

    F/V First Team Captain

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    Custom Boat Builder, SisuDiesel North American Sal
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    Narnia
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    Boat Make:
    Northern Bay 36 - Modified
    Contemplating either a 25/28 with either a 300/460 in either 2.5:1/2:1-1.5:1 two speed might be heat exchanged with wet exhaust, might be dry with a keel cooler
     
  6. Diesel Jerry

    Diesel Jerry Captain

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    What happened to the 496? Last I knew Volvo, Mercruiser, and Crusader was still offering that. They are a beast of a motor. I had one in a K5 blazer and damn.
    Come to think of it Leaky is putting a new 496 in his Holland.
    You can still get big blocks. Just need to know where to look.
    http://www.michiganmotorz.com/turn-engines-c-31_49_79.html
     
    Last edited: Mar 11, 2018
  7. Old Mud

    Old Mud Captain

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    Well hell yeah but who wants to pay $20,000 for a gasser ??
     
  8. Diesel Jerry

    Diesel Jerry Captain

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    True.
     
  9. Kodiakan

    Kodiakan Senior Member

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    I can’t believe what there getting for them these days. Not far off from a ReMan and definitely could pick up a good running take out for the same money
     
  10. Diesel Jerry

    Diesel Jerry Captain

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    They forgot the only thing they had on diesel was price! I think dad was quoted 25K for a ReCon 6BT last year.
     
  11. mike@mpi

    mike@mpi Senior Member

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    Occupation:
    mechanic- diesel,transmissions, and controls
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    stevensville, md.
    Boat Make:
    26 JC
    I didn't have the original gas engine in my 26 JC to compare to the 370B I put in it so I am using the previous owners numbers which may or not be accurate.
    1988 26 JC center console with a" Chrysler" Marine 340 hp - 460 cubic inch Ford turning a 2:1 velvet drive and a 17x14 Hytorq 4 blade.
    At WOT 4400 rpm 19 MPH @ 25 GPH.
    Cruise @ 3300 rpm, 15 MPH @ 17 GPH.
    Cummins 370B with 1.5:1 TwinDisc and 18x21 Michigan DQ 486.
    WOT 3070 RPM @ 26 MPH burning 18 GPH
    Cruise 2400 RPM @ 19 MPH burning 11 GPH.
    The boat is faster and uses way less fuel but is more expensive to build. 15 grand buys a lot of gasoline, but diesel is safer and now the clowns at the EPA are mandating catalytic converters or some sort of exhaust treatment on marine gas engines. As if exhaust risers weren't already enough of a problem.
     
    Last edited: Mar 13, 2018
  12. sevenjohn

    sevenjohn Senior Member

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    novi
    the question of gas or diesel has been around for a long time. still think its a question of what are you doing with the boat. my sons and i built a 33 young bros and put in a tier 2 jd 6068 265 hp. it has been good. we use the boat harpooning . boat has 650 hrs so far ..steam out ,jog around all day then steam home. in those hrs the boat has averaged 3.07 gals per hr. the boat cruise out at 16 and comes home at 16kts...lots of people pass me but i pass them by at the fuel dock. build for what you need.
     

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