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2755 ciera 7.4L prop choice-gctid383413

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    2755 ciera 7.4L prop choice-gctid383413

    I have a 93 Ciera with the 7.4L engine and bravo one outdrive. When I bought it, it had a 16 pitch prop, but after doing some outdrive repair, that prop was rubbing on the retainer so I put on my spare 19 that I had. The 19 seems to be way over propped as with just me onboard I made it to 40mph but only 4000rpm. My question is, what prop is others with this or similar sized and powered boats running?

    #2
    I know I am not the only 2755 Ciera owner out here?

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      #3
      kleake wrote:
      I have a 93 Ciera with the 7.4L engine and bravo one outdrive. When I bought it, it had a 16 pitch prop, but after doing some outdrive repair, that prop was rubbing on the retainer so I put on my spare 19 that I had. The 19 seems to be way over propped as with just me onboard I made it to 40mph but only 4000rpm. My question is, what prop is others with this or similar sized and powered boats running?
      That boat should have a B2 drive with that engine.

      Then a 18.25 X 19 would be good.

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        #4
        You are probably right, but this one is definitely the bravo one.

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          #5
          I believe 4400 is your max RPM for that engine. You boat even loaded couldn't weight more than 7000lbs.

          We also have a 2755 with a 5.8L and no where near the power you have, using a 15" x 17P and easily reach 40mph, with light load.

          With a 15.5 x 15 our 2755 does 35mph on a flat calm day.

          I agree, 19P should be the right prop, for your size of boat and that size of engine. Our 2859 is much heavier with a 18.25x19P, BII, 7.4L

          I wander if the drive ratio is the issue?

          Comment


            #6
            onthelake wrote:
            I believe 4400 is your max RPM for that engine. You boat even loaded couldn't weight more than 7000lbs.

            We also have a 2755 with a 5.8L and no where near the power you have, using a 15" x 17P and easily reach 40mph, with light load.

            With a 15.5 x 15 our 2755 does 35mph on a flat calm day.

            I agree, 19P should be the right prop, for your size of boat and that size of engine. Our 2859 is much heavier with a 18.25x19P, BII, 7.4L

            I wander if the drive ratio is the issue?
            I'm not sure what my drive ratio is, it's all stock, but yea, I am betting so. By the speed I was going at that rpm, I should have probably topped out at over 50mph, and i seriously doubt even a fresh engine would have pushed it to that. I'm thinking a 16 or 17 might be ideal.

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              #7
              I had a 7.4L in my 2550 and it did have the B2 outdrive. I had two props, a 18.25 x 21 and an 18.25 x 23. Ran with the 21 mostly and it performed very well with a loaded boat. The 23 did good with only me, my wife and a modest load, but not so well after you add more load and bodies. My thought would be, considering your boat is a little larger, that the 19 would be good, as suggested.

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                #8
                Here is some more details after testing another prop I borrowed from a buddy.

                Bought the boat with a 16p 4-blade prop on it. Did work on the outdrive, found out it had been grinding on the spanner nut and chewed it up. Replaced the spanner and can not run that prop without modification, and I do not know if it is the stock prop or not. (Previous owner I have found out, didn't know as much about boats as he pretended to). I had a spare aluminum 19p that I put on for the first run, but turned out to struggle to get on plane, and just was working way too hard. It did have decent top end, but would lose it in any turn and I couldn't back off much or I would continuously slow. I borrowed a buddies 15p large prop just to try, and really like the way it works. Top end isn't quite as much, but it feels close. It is a much larger prop than the 19 though as there is only about 1/2" clearance between the end of the blade and the drive itself, where the 19" will almost squeeze a 2x4 through there. I am thinking of either a 16 or a 17 in the larger diameter, but want some input before a commit. Here is a few numbers from each tested prop.

                19P aluminum 3-blade:

                Heavy load, major struggle to plane, tops out about 36mph at 3900rpm

                Just me on board, still a good workout getting on plane, tops out at 40mph at 4000rpm

                Cannot maintain 20mph without either falling off plane, or trying to take off once on plane. It's either 15mph heavy throttle, or move someone up front and all of a sudden I'm going 35mph at the same throttle position.

                15P SS 3-blade large diameter:

                22mph at 3000rpm

                26mph at 3400rpm

                37mph at 4500rpm

                It performed the same with heavy or light load. Never hit the rev limiter but would not go above 4500rpm (Tach could be innacurate, but seemed pretty close). Planed out quick and seemed to perform well. I could cruise at 25-27mph with ease and planed out very quick without moving anyone around to do it.

                Since I got more speed out of the 19p even at such a low rpm, tells me the engine has more torque around 4000rpm. I think I could easily go to a 16p, but "maybe" even a 17p. I am less concerned about going 40mph, but want a good cruise at about 25-30mph with the best fuel economy I can get. Also, should I go with the larger diameter prop, or the smaller diameter? I am thinking a 16p or 17p in the larger diameter, but that's just a guess.

                Comment


                  #9
                  kleake wrote:
                  Here is some more details after testing another prop I borrowed from a buddy.

                  Bought the boat with a 16p 4-blade prop on it. Did work on the outdrive, found out it had been grinding on the spanner nut and chewed it up. Replaced the spanner and can not run that prop without modification, and I do not know if it is the stock prop or not. (Previous owner I have found out, didn't know as much about boats as he pretended to). I had a spare aluminum 19p that I put on for the first run, but turned out to struggle to get on plane, and just was working way too hard. It did have decent top end, but would lose it in any turn and I couldn't back off much or I would continuously slow. I borrowed a buddies 15p large prop just to try, and really like the way it works. Top end isn't quite as much, but it feels close. It is a much larger prop than the 19 though as there is only about 1/2" clearance between the end of the blade and the drive itself, where the 19" will almost squeeze a 2x4 through there. I am thinking of either a 16 or a 17 in the larger diameter, but want some input before a commit. Here is a few numbers from each tested prop.

                  19P aluminum 3-blade:

                  Heavy load, major struggle to plane, tops out about 36mph at 3900rpm

                  Just me on board, still a good workout getting on plane, tops out at 40mph at 4000rpm

                  Cannot maintain 20mph without either falling off plane, or trying to take off once on plane. It's either 15mph heavy throttle, or move someone up front and all of a sudden I'm going 35mph at the same throttle position.

                  15P SS 3-blade large diameter:

                  22mph at 3000rpm

                  26mph at 3400rpm

                  37mph at 4500rpm

                  It performed the same with heavy or light load. Never hit the rev limiter but would not go above 4500rpm (Tach could be innacurate, but seemed pretty close). Planed out quick and seemed to perform well. I could cruise at 25-27mph with ease and planed out very quick without moving anyone around to do it.

                  Since I got more speed out of the 19p even at such a low rpm, tells me the engine has more torque around 4000rpm. I think I could easily go to a 16p, but "maybe" even a 17p. I am less concerned about going 40mph, but want a good cruise at about 25-30mph with the best fuel economy I can get. Also, should I go with the larger diameter prop, or the smaller diameter? I am thinking a 16p or 17p in the larger diameter, but that's just a guess.
                  I am no boat expert, actually i am as new as I can be, but i can tell u enough that when I got my 2755 in march, I was told i had a 454 with a bravo 1....Turned out I had a bravo 2. By the time I found out I had a B2, I already searched the web and called 20 bayliner dealers for a Bravo 1 size prop. I believe what I ran into was a 15 1/4 x 16p. Nothing higher than a 17P.

                  Then I was looking for a Bravo 2 prop - thinking I had to get the same size prop, but that works on a B2.

                  Turned out it wasn't the same thing. Actually the sizes for a B2 with a 454 usually come with sizes:18 1/4 x 17p or 18P or 19P. I've seen some go to a 21P with a bravo 2, some speedboats up to 23P.

                  Since you have a B1, I would not even bother to look at anything higher than 17P or you'll over power it. The good thing about the B1 props, they are 3 times as cheap as a B2 props.

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