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    #31
    Originally posted by boatworkfl View Post
    A pair of 300 hp Perkins marine engines would be a good choice for most Bayliners 38' and up.
    These engines are very reliable and very low maintenance and manufactured in the US.
    Only difference between the 300 hp and the 270 hp is the injectors.
    Tight in a 38' but will fit with a down angle transmission.
    I re-powered a 3870 with a pair of these, the boat tested 27 knots and the props were pitched up after the test run.
    I liked the Perkins engines we have owned.
    When I needed a manifold for my Perkins engine it came from Dorset in GB.
    They say all of their marine engines are made there....
    https://www.perkins.com/en_GB/compan...orne.html.html

    You can also add turbos and intercoolers to the 175 Hino engines in the 38 without too much work (fuel set for 220-230 hp) and get about 22 knots from the boat - 19 knots at cruise.
    No need to change the shafts, cutlass, exhaust ,transmissions, engine mounts ,controls and fuel system for that conversion.
    Northport NY

    Comment


      #32
      Many boat builders used these Cummins 8.3, not just in a Bayliner.
      Almost all Sea Ray 46, Tiara 3800, many down east boats had them.
      Cummins QSC 8.3 600HP is used in Sea Ray 590/510 fly, Beneteau 6, Prestige 550 & more.
      Dave Pascoe is one of the biggest Detroit Diesel fan... his first choice was the 6-71 in any boat where the power range is applicable for its longevity.
      DD 6-71s are designed to run hard, 8000 hours going strong on my 6-71s
      Joon, Kathy, Jaden & Tristan
      Uniflite 42 AC, DD 671N
      93 3058 sold
      92 2855 (day boat)
      91 Fourwinns 205 (lake boat)
      Longbranch WA
      Life is Good

      Comment


        #33
        Originally posted by Ruffryder View Post
        Many boat builders used these Cummins 8.3, not just in a Bayliner.
        Almost all Sea Ray 46, Tiara 3800, many down east boats had them.
        Cummins QSC 8.3 600HP is used in Sea Ray 590/510 fly, Beneteau 6, Prestige 550 & more.
        Dave Pascoe is one of the biggest Detroit Diesel fan... his first choice was the 6-71 in any boat where the power range is applicable for its longevity.
        DD 6-71s are designed to run hard, 8000 hours going strong on my 6-71s
        "Dave Pascoe is one of the biggest Detroit Diesel fan.." - was.... rest in peace.
        The 8.3 has none of the limitations of the smaller Cummins.
        Northport NY

        Comment


          #34
          Smitty, yes he was... RIP.
          I agree the 8.3 is much more robust than their 5.9, with mid-stop wet liners, one more plus.
          Joon, Kathy, Jaden & Tristan
          Uniflite 42 AC, DD 671N
          93 3058 sold
          92 2855 (day boat)
          91 Fourwinns 205 (lake boat)
          Longbranch WA
          Life is Good

          Comment


            #35
            Originally posted by talman View Post
            Hi, Doug. Long time, my friend. I have read of a lot of water ingestion issues, injector issue, and the like, but not on the 5.9L. I don't have a lot of experience (only 5 years now), but I know the blood lines of my 3488/341. They were previously pared with 250 4 cylinder, which was a very bad engine/paring. Kevin's Taz had v-drives and ingestion issues and his 4788 got new engines as part of his repo purchase, I don't remember the reason. The water pumps seem to be a problem. but beyond that, it seems to me that this block is a workhorse. In my size boat, the boat is effortlessly on plane, never seems taxed, even at WOT. The bigger boats ride a lot flatter and push less water than mine. Seems like they are well pared. They used to put 310 hino or 270 hino in the 4788, right? How is that different than a 330HP engine with a big cylinders type engine and boat that is going to run right in it's wheelhouse RPM wise. I bet RV's get harder treatment than our boats do.
            About the difference between RV and a boat. Boat is much harder on an engine. A boat has no gear selection and is always going up hill. My 40' motorhome with an 8.3 Cummins rated at 350 hp seldom sees more than 1800 rpms which is about 65 mph. It is able to rest going down hill, stops and so forth. It has gears that keep it from reving higher. 1500 rpms is about the shift point and that nets 55 mph on the open road.
            It doesn't see salt water. I know a boat diesel isn't all salt water cooled but its in the air and that does a bit more to an engine than not.
            Started boating 1955
            Number of boats owned 32
            Bayliners
            2655
            2755
            2850
            3870 presently owned
            Favorite boat. Toss up. 46' Chris Craft, 3870 Bayliner

            Comment


              #36
              Originally posted by Ruffryder View Post
              Many boat builders used these Cummins 8.3, not just in a Bayliner.
              Almost all Sea Ray 46, Tiara 3800, many down east boats had them.
              Cummins QSC 8.3 600HP is used in Sea Ray 590/510 fly, Beneteau 6, Prestige 550 & more.
              Dave Pascoe is one of the biggest Detroit Diesel fan... his first choice was the 6-71 in any boat where the power range is applicable for its longevity.
              DD 6-71s are designed to run hard, 8000 hours going strong on my 6-71s
              I would keep them just for the sound. Damn I love the sound of Detroits in a boat. Btw, $100,000 for a couple of 8.3 Cummins is insane.
              Started boating 1955
              Number of boats owned 32
              Bayliners
              2655
              2755
              2850
              3870 presently owned
              Favorite boat. Toss up. 46' Chris Craft, 3870 Bayliner

              Comment


                #37
                Is a boat really always going up hill? I agree, getting on plane is rough on any running gear. You are pushing a lot of water out of the way for a while, but when a boat is on plane is the engine really running all that hard if it isn't at WOT. I will give you that a lot of boats are under powered. My 2556 with a 454 and Bravo II was perfect compared to the same boat with a 350 and an Alpha, which I considered underpowered. My boat with a 4Cyl 250 would be working it's ass off all the time. I think the 380 QSB is ideal for this boat. I am propped properly, and pay attention to stuff. I get some do not.
                My oil samples did not indicate engine issues. Again, I only have 5 years under my belt on a 10 year old boat. I have more issues with my diesel Gennie than I do with my boat. Happy New Year to you an Mona. See you around.
                Tally and Vicki
                "Wickus" Meridian 341
                MMSI 338014939

                Comment


                  #38
                  Of course I'm keeping them. Some people think they're noisy, but music to many people's ears including me.
                  symmetrical engine...blower, exhaust, manifold, starter, oil/fuel filter and everything else could be mounted on either side of the block, nice for servicing two engines in a boat... enough about my DD.
                  that estimate also includes a pair of new ZF tranny & installed.
                  Agree a lot of boats are underpowered, heck Blackfin is dropping a pair of 6BTA 370s in a 31 footer.
                  Joon, Kathy, Jaden & Tristan
                  Uniflite 42 AC, DD 671N
                  93 3058 sold
                  92 2855 (day boat)
                  91 Fourwinns 205 (lake boat)
                  Longbranch WA
                  Life is Good

                  Comment


                    #39
                    Originally posted by talman View Post
                    Is a boat really always going up hill? I agree, getting on plane is rough on any running gear. You are pushing a lot of water out of the way for a while, but when a boat is on plane is the engine really running all that hard if it isn't at WOT. I will give you that a lot of boats are under powered. My 2556 with a 454 and Bravo II was perfect compared to the same boat with a 350 and an Alpha, which I considered underpowered. My boat with a 4Cyl 250 would be working it's ass off all the time. I think the 380 QSB is ideal for this boat. I am propped properly, and pay attention to stuff. I get some do not.
                    My oil samples did not indicate engine issues. Again, I only have 5 years under my belt on a 10 year old boat. I have more issues with my diesel Gennie than I do with my boat. Happy New Year to you an Mona. See you around.
                    Its a figure of speech Tally but yes it is. My motorhome, towing a car never gets more than 1500 rpms before it shifts. Shifts being important here. It has 6 speeds to get it up to speed. At crusing speed it runs 1500 to 1800 rpms or so getting 55 to 65 mph.
                    when a boat gets up to cruise speed, it struggles as you know. At this point you usually are giving it all it has with no gears so at that point you are lugging the engine. if you started with a small prop and changed 6 props reaching cruise speed you would not lug the engine.
                    At cruise speed a boat usually is at about 80% of its horsepower and you have increased horsepower compared to an RV. You have more horsepower with the 5.9 block than my motorhome has with the 8.3 block. Ponder that a minute and you will see your engine is working much harder. I think mine could go to about 600 hp. Even at 350 hp, I have lots left to pass when necessary.
                    What you are going is great. You should have no problems but don't abuse them.
                    An example would be you losing one engine for any reason and pushing the remaining engine to get home. If that should happen, run the boat about 6 mph, no faster. It could look like you are not pushing it because it isn't showing higher rpms but the reason is it can't reach them. You would be lugging the engine.
                    Another example might be in very heavy seas. so heavy you cannot get it on plane but you try to bull through them. You might be lugging them trying. If adding additional throttle doesn't get a rise in rpms, be concerned. Back off. Try running on one engine. After about 12 to 1500 rpms, you will see additional throttle does little. Abd your engine temps will rise. You can back off the throttle and still maintain your speed.
                    Of course over propping them would be abuse also. You might see an increase of top speed doing so but you won't reach suggested rpms and the engines would be lugging.
                    In short, my belief is with everything as mfg. suggests you are good. Its just there is no room for error.
                    Doug
                    Started boating 1955
                    Number of boats owned 32
                    Bayliners
                    2655
                    2755
                    2850
                    3870 presently owned
                    Favorite boat. Toss up. 46' Chris Craft, 3870 Bayliner

                    Comment


                      #40
                      Isn't the real issue operating temperature more so than load? As long as the engine is keeping it's cool, exhaust temperature isn't out of line, oil isn't too hot the engine is going to be happy to oblige.
                      Tony Bacon,
                      Washougal, WA
                      Caspian
                      1997 3788 Twin Cummins 250hp

                      Comment


                        #41
                        I think its almost one and the same. If you lug your engine for any distance temps will rise. On the other hand prop size is important. You want to be able to reach suggested rpms. If you can't you are over propped and that shortens the life of the engine. It may be the temps don't rise enough to be in the danger zone but you may still be lugging your engine. I run most of the time on one engine. If I run 1200 rpms or so they remain at normal temps. At about 1500 rpms I notice the temps start to rise. Not a lot but pushing it more shows 2 things. The temps rise even more and more throttle does little to nothing.
                        I know of one Bayliner with Cummins that lost an engine in a very few hours. The boat lost a tranny and the owner ran home on one engine. Knowing him I suspected he ran it hard on one trying to make time. And it was a long run.
                        That engine failed shortly after.
                        My personal feeling is you can abuse some engines more than others. For example the Hino engine non turbo'd has little horsepower for the size of the engine. the Cummins gets much more hp on a smaller block. Again my opinion there is less room for abuse on an engine peaked that high vs the cubic inches it has. A diesel should last almost the life of most boats yet we read of several Cummins that failed young. That should be cause for concern and caution.
                        Started boating 1955
                        Number of boats owned 32
                        Bayliners
                        2655
                        2755
                        2850
                        3870 presently owned
                        Favorite boat. Toss up. 46' Chris Craft, 3870 Bayliner

                        Comment


                          #42
                          Originally posted by Bacon View Post
                          Isn't the real issue operating temperature more so than load? As long as the engine is keeping it's cool, exhaust temperature isn't out of line, oil isn't too hot the engine is going to be happy to oblige.
                          It is not the temperature of the engine itself but the temperature of the cylinders - as you say it can be read directly in real time by EGT.
                          Once you run one of these boat engines with EGT gages it becomes more obvious that this can occur at various rpm - hence loading is important.
                          Cummins 6B's cannot tolerate high EGT's for very long , adding pyros in addition to following the 3 rules are a great insurance policy for engine life.

                          And as a byproduct of propping the boat safely you typically get a more economical operation with higher WOT speeds (although not important unto itself)
                          Northport NY

                          Comment


                            #43
                            An older related post we made way back....

                            We have recorded gage readings on our 1995 4788 equipped with 310 Hp WO6D TI-II engines. The boat had a clean bottom with 2/3 fuel , full water , moderate stores. The seas were 1' or less with a 65 degree air temp, negligible tides, in salt water. The pyro gages are mounted just after the turbine wheels and the boost gages read in the intake manifold after the intercooler. Tachs were strobed last year but may be slightly off and the speeds are an average from 3 gps’s.

                            Readings with 2 engines running in gear
                            RPM Speed (knt) EGT Boost (psi)
                            800 5.4
                            1000 6.5
                            1200 7.4
                            1400 8.3 400
                            1600 9.3 550 1.5
                            1800 10 650 2.5
                            2000 11.2 750 3.5
                            2200 12.3 850 5
                            2400 15 900 8
                            Then with one engine (starboard) only.
                            RPM Speed (knt) EGT Boost (psi)
                            800 5
                            1000 5.9
                            1200 6.6 400
                            1400 7.4 475
                            1600 8.1 575 1
                            1800 9 750 2.5
                            2000 9.8 900 5
                            We did not want to push the single engine above 2000 rpm’s and some of these readings were a surprise. When we currently cruise with 2 engines the EGT will stay at about 900 all the way to WOT and the boost will rise to 18-20 dependent upon conditions.

                            Hope this helps

                            Northport NY

                            Comment


                              #44
                              FWIW - one of the most common ways a boat owner unwarily overloads one engine is by using an engine synchronizer.
                              Sync'ing engines to be the same rpm when your tarns and props are not balance is the easiest way to inadvertently reduce load on one engine and increase load on the other.
                              We have seen many boats where one engine suffers the overload and needs to be rebuilt or removed and the other is mostly fine.

                              When you have pyro and boost gages and syn with them you will find that matching boost will have a matching pyro reading and your fuel use pt to stb will become almost exactly the same.
                              This can also be accomplished by matching well tuned fuel flow gauges.
                              Hope this helps
                              Northport NY

                              Comment


                                #45
                                Originally posted by smitty477 View Post
                                FWIW - one of the most common ways a boat owner unwarily overloads one engine is by using an engine synchronizer.
                                Sync'ing engines to be the same rpm when your tarns and props are not balance is the easiest way to inadvertently reduce load on one engine and increase load on the other.
                                We have seen many boats where one engine suffers the overload and needs to be rebuilt or removed and the other is mostly fine.

                                When you have pyro and boost gages and syn with them you will find that matching boost will have a matching pyro reading and your fuel use pt to stb will become almost exactly the same.
                                This can also be accomplished by matching well tuned fuel flow gauges.
                                Hope this helps
                                I don't see how this could be true. Even if one engine is loaded up more than the other, as long it's near or lower than the optimal cruise rpm, it's simply not overloaded. Plus or minus a hundred rpms on the other engine would be insignificant. If the other engine was off by something like 500 rpm then sure, it would be an issue, but if the tachs are accurate and both engines were close, then no worries.
                                1995 Bayliner 2452 Mercruiser 5.7L Alpha 1 Gen 2

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