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how can i get more power from my mercruiser 470

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  • how can i get more power from my mercruiser 470

    I have a 82 3.7 l thats rated for 170 HP. What can i do to get more HP?


  • #2
    Re: how can i get more power from my mercruiser 470

    you can burn it and make some BTU's for an old steam engine.......
    or dump the boat and pick up a similar size boat with a V8.
    That's realy about it.
    just because you found it that way does not mean it is supposed to be that way.

    Comment



    • #3
      Re: how can i get more power from my mercruiser 470

      theres a 4bbl manifold and carb that makles it a 190hp. you can probibly do more to hop it up but anything past that will kill the durability.
      jason if you dont have anyinthing constructive to say whey do you post?
      88 Larson Citation DC 175
      165HP 3.7L I4 (470) alpha 1

      Comment



      • #4
        Re: how can i get more power from my mercruiser 470

        Originally posted by abj87 View Post
        ... Jason if you don't have anything constructive to say whey do you post?
        It's called "increasing the post count" ... And a lot of people would love to see an old 470 burn...

        As your engine is a 1982 you have a small heat exchanger.. If you up the output, then you will definitely need to replace that exchanger with the big one, 5"

        Chris..........
        The world takes on a whole new perspective when viewed from 100' below...



        1972 Bertram 'Bahia Mar' 20
        2006 Mercruiser 4.3MPI (0W617679) w/Alpha 1 Gen II (0W829301)
        **
        Please don't send service questions in private messages. That's what the forum is for. Messages of thanks, always accepted.
        **
        Member of the month - April 2013. http://www.iboats.com/blog/achris-member-of-the-month/

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        • #5
          Re: how can i get more power from my mercruiser 470

          Originally posted by abj87 View Post
          theres a 4bbl manifold and carb that makles it a 190hp. you can probibly do more to hop it up but anything past that will kill the durability.
          jason if you dont have anyinthing constructive to say whey do you post?

          Sheesh! Rough crowd these days!


          Fact is, even if you "hop" it up, 20hp is just not going to make much difference.

          If you want more "seat of the pants" hp. (read TORQUE) You're just going to have to get more cubic inches......or more induction air (turbo/blower) You do that and you'll kill that 470 quicker than they regularly die.

          Your best bet is to get a V-8...... but that will cause a HOST of other problems you'll need to solve like engine mounting, transom plate/shield, drive ratio, prop pitch, etc.

          Unless there's some sort of sentimental value in your boat you might be better just selling it and getting one that performs the way you want it...


          Cheers,


          Rick
          ----------------------------------------------------------------------------------
          I use xxx oil and have never had a problem........
          This post was created with OpenSuSE x64 Linux!

          Comment



          • #6
            Re: how can i get more power from my mercruiser 470

            Most of us would like some more HP, but the best thing to do is just keep its as is and run the thing. Depending on your boats weight you probably have a pretty high power to weight ratio as is. Hell mines faster then the 19ft ebb tide with a 4.3 and about even with the 24ft sea ray with 350mag
            88 Larson Citation DC 175
            165HP 3.7L I4 (470) alpha 1

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            • #7
              Re: how can i get more power from my mercruiser 470

              What size and type is the boat? What would you do with the extra HP if you could get it? Do you have a performance problem now like poor hole shot or very low top speed? Maximizing all other components like prop pitch/cup/blade count and hull weight/balance and maybe even adding SmartTabs can help your boat do more with the HP that is there.

              Let's say you could get another 20 hp easily, maybe 30. With all else being equal that may give you 2-3mph on the top end. The hole shot would be the same, and even the midrange until the rpm's get past 3,500, see what I mean? Most of what you feel now is from the torque curve of that engine. The torque curve won't change much until the 3,500 rpm mark by my best guess, and you may be disappointed after all the expense and time spent and wish you had spent the time and effort on other areas of optimization.

              Those engines have a lot of torque which makes up for any perceived lack of HP in the rating. Keeping it in tune is the best way to get "extra" HP, just make sure it stays in tune so you get all of the ponies all of the time.



              I'm just sayin'....
              1991 HydroSwift 2200 Cuddy Volvo Penta 570/DP
              1980 Glastron SSV167 90HP Mariner

              Comment



              • #8
                Re: how can i get more power from my mercruiser 470

                If you think I'm bad, try catching Don or rodbolt or bomar on one of their "off" days.

                Originally posted by abj87
                jason if you dont have anyinthing constructive to say whey do you post?

                Becuse i'm most definitely padding my posts

                And I did say something constructive, I said loose the boat and get something with a bigger engine.
                Just because I didn't explain all the poor qualities of the 3.7 so you could understand them (besides, it's all in the forums if you use that little search function) doesn't mean what I said was any less constructive.
                just because you found it that way does not mean it is supposed to be that way.

                Comment



                • #9
                  Re: how can i get more power from my mercruiser 470

                  There are guys who have hundreds of hours on tuned 470s over at breezy.

                  http://www.breezeworks.net/cgi-bin/M...1&ThreadPage=1

                  It all depends on what you have now and what you want to do.

                  1) Upgrade the ignition to a Pertronics from points.
                  2) Upgrade to an alternator from the OEM stator.
                  3) If you have the original 3" heat exchanger and have overheat issues you should upgrade to a larger version.
                  4) Replace the 2 brl carb/manifold to a 4 brl version. Tune it.
                  5) Replace the OEM rockers with roller rockers. Increases HP and much less heat generation.
                  6) Remove blockages in exhaust system.
                  7) Upgrade to higher compression pistons.

                  Ask yourself what you have and what you want. There are guys who have hundreds of hours on engines that were rebuilt as above and get 210-240 hp out of them. That's a great power to weight ratio but it is a out of production motor. There are tons of them around for parts still and the internals are cheap. Some other components are not. Would you be happy with a simple prop change? Is your motor not putting out well because it needs maintenance? Know where you are at before spending time and money going somewhere else. Its a lightweight and easy motor to work on. If you have no inclination to do the work then it gets expensive. Then again, all of your other options are expensive too.

                  Comment



                  • #10
                    Re: how can i get more power from my mercruiser 470

                    Originally posted by abj87 View Post
                    Hell mines faster then the 19ft ebb tide with a 4.3 and about even with the 24ft sea ray with 350mag
                    Yeah, great, you still have a 17' boat, though. I'll take a 17' with a 4bbl 4.3 and smoke your 470!

                    Best reliable way to increase the power on a 470 is to replace it with a V-8. Sorry if you think that isn't a productive quote, but it's the only true statement, and you all know it!

                    Comment



                    • #11
                      Re: how can i get more power from my mercruiser 470

                      Originally posted by TilliamWe View Post
                      Yeah, great, you still have a 17' boat, though. I'll take a 17' with a 4bbl 4.3 and smoke your 470!
                      umm yeah im sure a hoped up 4.3 would smoke it but a stock carbed 4.3 wont be much diffrent. But thats not the point i was trying to make! What i was trying to say is depending on how heavy his boat is its performance is probably pretty good compared others.

                      i didnt mean to step on anyones toes but. but telling somone to burn his boat is not very helpful.
                      i DO agree if a big power increase is wanted the best thing to do is get another boat with a v8. But that's not what he asked, he wanted to know how to get more power out of a 470!
                      88 Larson Citation DC 175
                      165HP 3.7L I4 (470) alpha 1

                      Comment



                      • #12
                        Re: how can i get more power from my mercruiser 470

                        I have a 19 foot rinker with a 15 1/4 by 21 prop it runs good and is good on power but id just like some more. Without burning the boat or dropping in a bigger motor. I like my boat its fast to me and i will not burn it. I got some nice answers like the one from newbster but i also got some that are just plain rude. If i wanted to get a differant boat i would have and not bothered to ask. All i asked for was some hop up tips. Im not trying to make a race boat and i dont want to ruin the reliability of the motor. But thanks for all the help.Also newbster what did you mean by removing blockages from exhaust?

                        Comment



                        • #13
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                          Re: how can i get more power from my mercruiser 470

                          You haven't mentioned what you have done so far, or even what the current performance is. Doing more with the HP that is there is a good first step. Anything done to the boat to optimize it now (before any HP add-ons) will only get better if more HP is added. You do have to take some baseline numbers down, and they need to be accurate.


                          For any given prop:
                          • WOT throttle RPM
                          • Top Speed at that rpm

                          Start from there as your baseline to se if you went the wrong way with any adjustments later.

                          The proper prop is a big part of how any boat performs. If you can still hit the top end of the recommended rpm range with the 21 pitch then it may be worth trying the next pitch up. If it is at the low end of the top rpm range then best leave it at the 21 pitch.

                          You may be able to optimize your hull's performance also and do more without bothering the engine. Smart tabs can get it to plane sooner which helps it accelerate faster. They are designed specifically for a boat like yours. When properly dialed in they can increase top speed and allow your trim setting to make more difference at tuning in for a top speed run. Sometimes these improvements can allow you to go another pitch up on the prop and still get the same acceleration from a dead stop and also get the higher top speed from the higher pitch.

                          In any event it is important to take note of your baselines to before you start.
                          1991 HydroSwift 2200 Cuddy Volvo Penta 570/DP
                          1980 Glastron SSV167 90HP Mariner

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