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3.0 Mercruiser performance options

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  • 3.0 Mercruiser performance options

    Has anyone heard of any performance options for a 3.0 merc 140 horse? My boat is a 18 ft Sea Ray and it runs WOT at 44-4600 and it does 38-40 which is plenty enough for skiing ect. My problem is I need that extra bit of UMMMMPH for getting across the lake fast or for pulling my larger sized bro on law without boggin down. I have read about guys who build outrageous stockcar engines using 3.0 parts and apparently make like 250 hp. I don't want to go that far but maybe 50-75 more ponies. Any advise or URL would help. I have 14 years experience working on cars so technical style answers are ok.


  • #2
    Re: 3.0 Mercruiser performance options

    Easy to do.......pull drive, yank engine, etc, drop in SBC (ZZ4 crate are great. watch for reversion), install new drive w/ correct ratio, and away you go. Any other attempts at performace mods to the Industrial engine that is the Merc 3.0 are spitting in the wind.Real world answer:Sell boat, buy one with adequate power fo what your intended useage is.
    The last time religion controlled the world it was known as the Dark Ages

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    • #3
      Re: 3.0 Mercruiser performance options

      Have you ever heard of power to weight ratio? I don't want to have a 500 lb engine(not to mention more fuel usage, extra parts ect) just to go 15-20 mph faster. The lighter I am the faster I go. I want to keep it that way and really the reason is that I love the boat.(and don't want to spend the $$$ for a different one)

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      • #4
        Re: 3.0 Mercruiser performance options

        16 HP per ONE MPH gain is a good rule of thumb in the marine world.....Again, your solution is above.There is no magic answer.
        The last time religion controlled the world it was known as the Dark Ages

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        • #5
          Re: 3.0 Mercruiser performance options

          Originally posted by Scott Atwater: Have you ever heard of power to weight ratio? I don't want to have a 500 lb engine(not to mention more fuel usage, extra parts ect) just to go 15-20 mph faster. The lighter I am the faster I go. I want to keep it that way and really the reason is that I love the boat.(and don't want to spend the $$$ for a different one)
          You are not dealing with automotive here Scott, what you want is impossible.Deal with it.
          Don S.

          sigpic

          Please, no PM's (Private Messages) regarding boat/engine problems.
          That is what the forums are for.
          Only forum/moderator issues will be answered in PM's.

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          • #6
            Re: 3.0 Mercruiser performance options

            I am basing my findings on a friend of mine who has the same boat(year, length ect) but with a 170 engine in it. He is actually only a tad bit faster. I think weight has everything to do with it. Why else would they make carbon fiber race hulls which weigh 800 lbs vs standard heavier fiberglass weight? It's true with cars and planes I also feel with boats this is also true. Less weight means less drag=go faster. Now I know what someone is going to say gut the boat and weigh less which is NOT an answer so don't go there.As for the engine doesn't anyone know of cams, pistons(high compression)maybe some porting, a small four bbl ect which will work? Sound like you guys are the v-8 block is the best in the world guys and frankly I don't think that is true anymore. The old 4.3 liter vortec makes 190-210 hp and it's 3/4 of a smallblock. Look at how they make so many beter products with more power ect than the years prior with better technology ect. Also is the alpha 2 3.0 a higher hp engine?

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            • #7
              Re: 3.0 Mercruiser performance options

              Don S.

              sigpic

              Please, no PM's (Private Messages) regarding boat/engine problems.
              That is what the forums are for.
              Only forum/moderator issues will be answered in PM's.

              Comment



              • #8
                Re: 3.0 Mercruiser performance options

                i wish i had a dollar for every time i've seen a post about "more hp out of a 3.0". then i'd have enough money to pull my 3.0 and get a v-8
                1985 Wellcraft 170 American / 3.0 Alpha 1

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                • #9
                  Re: 3.0 Mercruiser performance options

                  About the only way to make MORE HP in a small motor is to spin it really fast problem is that the outdrive really really does not like driveshaft RPM above 5000And just study that mess of a combo intake/exaust manifold NOT really a lot to work with tommays
                  If a dirty bottom slows you down what do think it does to your BOAT

                  1970 Cal 29 Sea Fever
                  http://cal29seafever.blogspot.com/
                  1981 J24 Tangent 2930
                  http://s565.photobucket.com/albums/s...%20for%20sale/
                  Tommays
                  Northport Ny

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                  • #10
                    Re: 3.0 Mercruiser performance options

                    Ayuh,........ You can make a Race Car engine turn 10,000rpms to get Big HorsePower.......You Can't do that to the Tractor Motor that the 3.0l IS.........With 14 Years of being a Mechanic,....... You Seem to be Missing the Basics of Building USABLE HorsePower.......You Could use 12/1 350 Pistons,.... But it Still Won't Work...........Nobody is Arguing that Lighter is Faster,......
                    Any Grease is Better,..... Than No Grease at All.......

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                    • #11
                      Re: 3.0 Mercruiser performance options

                      What they said...the curve is not linear...My 17.5 foot boat had a 140 3.0 and it went 40mph,My other identical hull (see avatar) has a 3.8 V6 @170 HP and it goes 50 mph, but with a SS prop. It's capable of almost 2X the fuel consumption.The weight of the V6 obviously is not too serious an issue.The first thing I would look at before upping HP is the fuel tank size... I just sized up some tanks for a retrofit...not looking forward to it tho'

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                      • #12
                        Re: 3.0 Mercruiser performance options

                        trade your boat or sell it.get what you want with factory aplication and youll have no troubles.or better yet--tell bro in law to get a boat and ride with him a while.

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                        • #13
                          Re: 3.0 Mercruiser performance options

                          here is the solution, build yourself a v-8 using all alumimm parts, block, heads intake , you can even get the exhaust logs in alum. now you dont have a weight problem, and since money is no problem here, get this thing fuel injected. at 75-80 mph, you will be asking how to make that hull, which is designed to do just what you are doing, handle better..... the perfect boat is not there yethave a great holdiay

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                          • #14
                            Re: 3.0 Mercruiser performance options

                            Doing a lot a reading on this subject and i afraid it useless. Basically if i have this right the 3.0 has been tuned to run @ high rpm's (4800) leaving it a tad weak in low end tourqe. Now if some one could find a way to increase the tourqe dramatcally on the bottom end and still maintain the top end then a bigger prop would seal the deal... Good luck on that one. Hmm maybe fuel injection.....$$$$$$$$. Notta
                            Stickly a opinion your milage may vary.

                            Speed is how fast you hit the wall
                            Torque is how far you move the wall"

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                            • #15
                              Re: 3.0 Mercruiser performance options

                              to go along with "stock car racing engines" i raced a 4 cyl class for many years. we ran a pinto with a 2.3 liter. it produced around 250 h.p. but it didnt really "wake up until 6000 rpm's. with a spare engine still in the garage, i thought id look for a bayliner that also used a 2.3, and put mine in. upon calling OMC, they said the outdrive bearings would explode before the motor ever reached its "desired" rpm. thats the end of that idea.
                              1985 Wellcraft 170 American / 3.0 Alpha 1

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