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Thread: Bayliner 2859 repower with FNM diesel?

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    Default Bayliner 2859 repower with FNM diesel?

    I am thinking of repowering a 2859 Bayliner with the new FNM 250hp diesel and Mercruiser Bravo II stern drive. Engine and drive will total approx 800lbs vs current 200hp Cummins at 1300 lbs with same drive. From my experience with this and other diesel planing hulls I think I can get 20kt cruise. Only got 15-16 w/Cummins. Any thoughts before I make up my mind. thanks

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    I was looking at the same engine for my 2000 2859. I currently have the 7.4 MPI with a Bravo ll. Do you know the gear ratio in your Bravo ll?

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    Quote Originally Posted by Kojak890 View Post
    I was looking at the same engine for my 2000 2859. I currently have the 7.4 MPI with a Bravo ll. Do you know the gear ratio in your Bravo ll?
    I am now going with the Bravo III drive and the FNM250. After checking I am sure I will get better performance and efficiency with the dual prop. The gear ratio with the Bravo III is 2.4 with 20" pitch props. I believe my Bravo II drive is 2.0. I am finalizing order for engine/drive package now and hopefully will have in Juneau for installation in approx two weeks.

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    Member Sobie2's Avatar
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    Sounds sweet "stelias".... you Yakutat guys are so un original with your names.

    Definately will be happy gaining 50 diesel HP and putting it to use with a Bravo III. You realized that your are losing propeller RPMs by going from a 2.0 to a 2.4 I'd have gone with a 2.0 or less ratio if the diesel Bravo III had that as an option. You have a lot power now and a high speed hull. Make sure what ever you do that you are allowed to test a few prop combinations before finalizing things and offering final payment. Your combo will have an obscene ammount of torque to swing the upper end of the prop range.

    Sobie2... not very original in my name either.

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    Default FNM

    Well it has been a few weeks, did you have the FNM installed? Let me know how it performs and what the fuel efficiency is.. I'm sure I will repower my 2859 this winter.

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    Member Dupont Spinner's Avatar
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    You should at least match the gear ratio of the unit you are replacing. A 2.0 for 2.0 etc. Now if you are changing from a gas to diesel you should lower your ratio. The Bravo III diesels drives are geared from 1.5 to 2.2 to 1. If under geared you can go as large as 30" pitch for the Bravo III but stuck at a 20" pitch for the smallest pitch to bring your rpm's up if required. All of course if your not trying to twist your diesel at 5000 rpms.

    I am running a 2859 still on gas (MPI 350) and upgraded last year to the B III and I am loving it. I matched the gear ratio (2.0 to 1) and prop pitch was close. It was a B II and 21" pitch prop and I dropped it to a 19" before swapping to the B III. On the B III I kept the same ratio and the 20" pitch was a great match. Hindsight I would have went with the 2.43 for a little more prop range. My cruise is about 23 knots and topend I get about 35 to 37 knots depending on load.

    There is a few diesel 2859's down in Valdez that I seen done to include one with a monster turbo Volvo diesel. I even knew of one here in my area that had a BMW diesel installed. Seems to be a great combo just lose a little cruise speed vs gas vs a little better fuel mileage.

  7. #7

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    Good morning! The engine is here and boat is in shop. Bravo III gear ratio is 2:2 and prop pitch is 20. Getting very anxious!

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    Quote Originally Posted by Dupont Spinner View Post
    You should at least match the gear ratio of the unit you are replacing. A 2.0 for 2.0 etc. Now if you are changing from a gas to diesel you should lower your ratio. The Bravo III diesels drives are geared from 1.5 to 2.2 to 1. If under geared you can go as large as 30" pitch for the Bravo III but stuck at a 20" pitch for the smallest pitch to bring your rpm's up if required. All of course if your not trying to twist your diesel at 5000 rpms.

    I am running a 2859 still on gas (MPI 350) and upgraded last year to the B III and I am loving it. I matched the gear ratio (2.0 to 1) and prop pitch was close. It was a B II and 21" pitch prop and I dropped it to a 19" before swapping to the B III. On the B III I kept the same ratio and the 20" pitch was a great match. Hindsight I would have went with the 2.43 for a little more prop range. My cruise is about 23 knots and topend I get about 35 to 37 knots depending on load.

    There is a few diesel 2859's down in Valdez that I seen done to include one with a monster turbo Volvo diesel. I even knew of one here in my area that had a BMW diesel installed. Seems to be a great combo just lose a little cruise speed vs gas vs a little better fuel mileage.
    I now have the complete engine and drive package and boat in shop! Bravo III gear ratio is 2:2 and props are 20's. I have option of returning props if required. By the way I found the 2859 to be very stern heavy with 1,200 lb Cummins and only 200hp. I was forewarned by another owner and had larger hull trim tabs installed and they helped. With more than 400lbs less engine weight that by itself should help in addition to 50 more hp.

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    Member Dupont Spinner's Avatar
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    I wish I was a little heavier on the stern then I am. When I am sitting static the boat sits a little nose down. In addition to the the kicker, I still need about 250 to 300 lbs on the swim deck to level things out sitting still. My 2859 is the 1st year of the small blocks and I don't think they quite had the balance handle yet for the smaller package. I have moved some things around to make it better but still need a little more. On extended trips I am fine as I store another 90 gallons of fuel out back.

    Good luck with your swap and please let us know how it all works out. Always interested in something different.

    Have a question.....are you using the gearbox and what is it's function? Reduction or overdrive? Or is it not needed with the Merc Drive?

    My guess from pulling on the specs on the engine is you may be looking for a 22" and maybe even 24" props. Mercruiserwas suppose to be working on some 4 blades for the BIII but have not seen anything official.

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    Quote Originally Posted by Dupont Spinner View Post
    I wish I was a little heavier on the stern then I am. When I am sitting static the boat sits a little nose down. In addition to the the kicker, I still need about 250 to 300 lbs on the swim deck to level things out sitting still. My 2859 is the 1st year of the small blocks and I don't think they quite had the balance handle yet for the smaller package. I have moved some things around to make it better but still need a little more. On extended trips I am fine as I store another 90 gallons of fuel out back.

    Good luck with your swap and please let us know how it all works out. Always interested in something different.

    Have a question.....are you using the gearbox and what is it's function? Reduction or overdrive? Or is it not needed with the Merc Drive?

    My guess from pulling on the specs on the engine is you may be looking for a 22" and maybe even 24" props. Mercruiserwas suppose to be working on some 4 blades for the BIII but have not seen anything official.
    The Bravo III gear is a reduction 2:2 to 1. Now that you have mentioned the need for weight in stern on you 2859 I have rethought and believe that the real issue with mine isn't too much weight in stern rather just not enough diesel horsepower. In any event having 4-500 lbs of weight off boat will not hurt.

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    Quote Originally Posted by stelias View Post
    The Bravo III gear is a reduction 2:2 to 1. Now that you have mentioned the need for weight in stern on you 2859 I have rethought and believe that the real issue with mine isn't too much weight in stern rather just not enough diesel horsepower. In any event having 4-500 lbs of weight off boat will not hurt.

    That Cummins was 1100 to 1200 lbs if I remember right. Thing should really move out for you with the new package.

    Those 2859's with big blocks sit level in the water, diesels slightly stern down and small blocks are nose low.

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    Member Sobie2's Avatar
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    Dupont Spinner:

    Maybe do a good boat cleaning out. Those 2859s hold a lot of stuff up in front of the boats center of gravity. Move what you can to the bildges and in that aft berth.

    Sobie2

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    Member Dupont Spinner's Avatar
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    Quote Originally Posted by Sobie2 View Post
    Dupont Spinner:

    Maybe do a good boat cleaning out. Those 2859s hold a lot of stuff up in front of the boats center of gravity. Move what you can to the bildges and in that aft berth.

    Sobie2
    Thanks for the reminder.

    I actually keep very very little up front. The grill, spare prop up front, some extra bedding, waders and boots, Life jackets under the seat, bumpers and line under the table, food under the cabinet, pots and pans under the sink. That's it. We run very light normally. Extended trips we run heavier but thats expected. That was the 1st thing I checked when I noticed the nose low. I have gone thru the trouble of checking to see how much I needed to add to the rear to level out at idle and it's almost exactly the differance in weight between a smallie vs a biggie. It doesn't seem to effect the way she runs overall.

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    Default Bayliner 2556 using FMN 250 hp

    Hi
    I am in New Zealand. I have a bayliner 2556 that I have repowered with a FNM 250 hp / Bravo 3 2.2 / 20 inch pitch. I have down 100hrs on this unit.
    Top speed 23 knots 4200 rpm 17 knots 3400 rpm.
    Has any body fitted this combo into any bayliner model

    Thanks
    Graham O

  15. #15

    Default FNM 250 repower Bayliner 2859

    I am in process in Juneau, Alaska of repowering Bayliner 2859 with FNM 250 and Bravo III outdrive. Same gear ratio as yours but initially with 22 props. Should be in water for testing in ten days or so. Do you have any thoughts based on your repower?

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    Default Fnm 250 hp Repower

    Hi Stelias

    Have had a few problems with the motor. Put the boat in the water with 2.0 ratio and 20 inch props to start with. Found the boat would only rev to 3400 rpm. Had the motor checked by agent who could not fault. Run the boat for another 10 hrs at no more then 2800 rpm as to not over load motor. Then had turbo blow up big time at 2800 rpm. Oil all over new white paint in engine space. Replaced turbo.
    10 hrs later fuel cut out sensor failed, motor stopped running.Peplaced sensor.
    Then main CPU failed Replaced
    Then electric fuel pump failed Replaced.
    By now was getting little up set with motor.
    Agent then replaced stern leg with 2.2 ratio still with 20 inch props.
    This we hoped would enable motor to rev to 4000 rpm.
    With a very clean bottom and light load the motor will rev to 4000 rpm.
    I also replaced the trim tabs with a size double what came on the boat.
    With a dirty bottom the boat will still only rev to about 3450 rpm.
    I will be very interested in how your boat runs as it is a bit bigger and weight is more.

    Best Regards
    Graham O

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    I visited NZ several years ago with Hawaiian friends to see Hector Busby and his Waka on North Island Doubtless Bay. You have great country to which I will return!
    Wow--you are scaring me with litany of engine issues--but we shall see. Alaska dealer has been running twins in his charter boat for several seasons with no problems, so have fingers crossed for good luck!

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    I am sure that all will go well with your FMN. Let me know how it works out for you.

    Thanks
    Graham O

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    Thanks for sharing the great list and have done a great article with complete and interesting information. I found my state in the list and enjoy your article too. Thanks again for nice information.
    ______________
    women's black titanium bands | Addsiteurls Directory | Addtexturls Directory

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    Quote Originally Posted by Jasmin View Post
    Thanks for sharing the great list and have done a great article with complete and interesting information. I found my state in the list and enjoy your article too. Thanks again for nice information.
    ______________
    women's black titanium bands | Addsiteurls Directory | Addtexturls Directory
    Finally finished with installation of FNM 250 w Bravo III drive. Am in process of break in with 10 hours on engine. So far have reached WOT 4000rpm so may need next size down props, but will wait for dealer to do engine speed/load analysis while underway with present props. At 3200 rpm with full fuel and water and one aboard get 18kts. at 3400 get 20+kts(still playing with trim angles). WOT got 25+kts. This as mentioned is a Bayliner 2859.

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