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HP rating at prop vs. powerhead

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  • HP rating at prop vs. powerhead

    I've got a friend who's been telling me the difference between today's motors is that they are rated at the prop, rather than the powerhead, as they were 10-15 years ago. I'm inclined to think he's an idiot, for various other reasons, but can anyone put this to rest for me? I'd like to think I'm getting more than ~55hp at the prop, but some days I'm not so sure. My 17 is disproportionally slow to plane as a friend's 17 Montauk with a new 90 Bomb.

    If it's true, what was the time frame that engine mfgrs started rating at the prop? What's the approx. reduction in hp between the powerhead and the prop... is it that significant?[?][?][?]
    \'72 Mako 17, Suzuki 140 FOR SALE[br]\'74 Mako 19B Project FOR SALE[br]Seabird 21 Project FOR SALE[br]San Juan 28 sailboat [br]Wake, VA[br][IMG]

  • #2
    Your buddy is right. Can't give you a time frame.

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    • #3
      10/4
      ..........

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      • #4
        October 4th?[:x)]

        Would you fathom a guess at the % in hp reduction between the powerhead and prop? 10%? 25%?
        \'72 Mako 17, Suzuki 140 FOR SALE[br]\'74 Mako 19B Project FOR SALE[br]Seabird 21 Project FOR SALE[br]San Juan 28 sailboat [br]Wake, VA[br][IMG]

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        • #5
          Your friend is right

          jbsmako

          '73 23'mako

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          • #6
            Your friend is definitely right. Not sure about the dates, but I'm pretty sure it coincided with Coast Guard regulations and insurance issues. I know because the twin 200s is more than max HP rating for my boat and I researched trying to find a loophole to insure the boat a little cheaper, no luck for me though.

            Another reason was to compare apples to apples between manufacturers. The actual HP has to do with gear ratios, torque efficiency, and 100 other Engineering formulas I can't remember. These days, they put the motor on a special dynometer that measures the actual torque output at the prop. These are the "performance" HP used in sales. The number on the side of the cal is the HP relative to "estimated" HP when considering #/size of pistons and compression etc. Can't remember that formula either...[:0].

            The SKA and racing factory reps will actually dyno individual motors off the assembly line and chose the highest HP numbers. I heard of a 225 Yamaha HPDI actually producing 268 hp when dyno'd. Impressive.
            Artie Sutherland[br]Rude Attitude -\'76 Mako 25 CC. - SOLD[br]1976 Mako 21[br]2002 Yellowfin 31 - 300 hp Suzukis[br]Gulf Coast, Mississippi[br]

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            • #7
              So that means that the old 200 I've got, (1983) probably doesn't make as much power as today's 200. And, if I were to go to a new 225 I would probably notice a huge difference right??
              1982 224 w/200 \'Rude[br]Andover, CT

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              • #8
                Theoretically. Depends on the motor manufacturer mainly. This was only a game played by some of the motor builders back when if I remember correctly. My 200s are 230+ at the prop. Evinrude is one of the engines known for under estimating, I think Suzuki is the same way. Mercury is not. The old antic "OMC for power, Merc for speed" back in the 80s-90s personifies this. Has to do with the gear ratios mainly.

                Look at the specs for the motor you wanna buy and it will tell you both numbers normally. Again, prop size and gear ratio are the main influence that differentiate actual vs theoratical HP numbers for any given motor.

                You will also get better performance from a newer engine because of weight, injection vs carbed, etc.... again, a lot of factors.
                Artie Sutherland[br]Rude Attitude -\'76 Mako 25 CC. - SOLD[br]1976 Mako 21[br]2002 Yellowfin 31 - 300 hp Suzukis[br]Gulf Coast, Mississippi[br]

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                • #9
                  Rude,

                  I can get a brand new 225 Opti for $11,500 vs a 225 Etec for $16,000. Do you think that the difference in price is worth the difference in power rating calculations? What i understand you're saying is that the Rudes (I know are much better engines) are in fact more powerful in hp and torque than the Mercs.
                  Past:[br]1988 Mako 230[br]1987 Mako 20C (best of them all)[br][br]1974 Mako 15[br]Miami, FL[br]

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                  • #10
                    I would say compare the Optimax 225 vs the Evirude 200 and the actual HP will be closer (just an educated guess, so check the numbers). Look at the Suzuki/Johnson 4 strokes for numbers also as they are the lowest gear ratio in the 4 strokes at the moment. How about a 225hp 4 stroke Johnson for $12k...[] Not bad.

                    check here for better prices

                    http://www.edsmarinesuperstore.com/

                    If you are willing to drive a ways and feel comfortable or know someone who could install the motor for you, out of state is the way to go as there are no taxes.

                    The other thing to consider is the cost of outfitting the changes from one manufacturer to the next. Throttle controls, props, cable, guages, etc can add up fast.
                    Artie Sutherland[br]Rude Attitude -\'76 Mako 25 CC. - SOLD[br]1976 Mako 21[br]2002 Yellowfin 31 - 300 hp Suzukis[br]Gulf Coast, Mississippi[br]

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                    • #11
                      Thanks for the info. I'm stuck in sunny Puerto Rico so there's not much room for negotiation. On the plus side there's no sales tax, and I'm good friends with the BRP Marine division dealer. He says he'll sell me a Rude or Johny for a couple hundred bucks over invoice (can't beat that). Suzy marine dealer went bankrupt, so that's that.

                      BTW do you know the difference between Suzuki 4stokes and Johny 4strokes. Seem like the same thing except for the paint.
                      Past:[br]1988 Mako 230[br]1987 Mako 20C (best of them all)[br][br]1974 Mako 15[br]Miami, FL[br]

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                      • #12
                        Only a paint change. I guess Bomb knows a good thing when they see it.

                        I'd opt for a 200 DI Evinrude before the Optimax even, especially if you get such a deal. [] The E-tec is the cat's ass though.[)]

                        Good luck.
                        Artie Sutherland[br]Rude Attitude -\'76 Mako 25 CC. - SOLD[br]1976 Mako 21[br]2002 Yellowfin 31 - 300 hp Suzukis[br]Gulf Coast, Mississippi[br]

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                        • #13
                          I am going out on a limb here and say it was the early to mid 90's when the american engine builders followed yamahas lead and started rating there motors at the prop. I remember this from an article in trailer boat mag. and I stoped getting that mag. in the mid 90's.

                          so this is my best guess. dave
                          [br]1994 Mako 215 Dual console Optimax 225[br]1978 Mako 19 with 90hp johnson[br]1996 Mako 22[br]1982 Mako 171 Angler 135 Black Max Mercury[br]1987 21b 225 Yamaha[br]1974 23 inboard Gusto gone.[br]1979m21 225johnson \"blue dolphin\" bought off this board and restored [br]with everyone\'s help!!Gone but not Forgotten....[br]1979 20 Mako 115 Suzuki gone[br]1977 19 Mako 115 Johnson gone[br]1976 23 Mako twin 140 Johnsons gone[br]1983 224 with closed transom and bracket[br]And 162 SOB (some other boats)[br]Venice Florida, Traverse city Mi.

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                          • #14
                            I think around 1986 was when it went from powerhead to prop ratings.

                            The guys at screamandfly.com can tell you almost anything you need to know about outboards.
                            1971 17 Standard[br]Clemson SC

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                            • #15
                              Re: Ed's Marine... He has the lowest prices, period. All the other dealers seem to hate him for it, in addition to the apparently lousy service. But heck, if you are willing to ship, I'm sure you can save by going to him. I stopped by their display at the VA Beach Boat Show last night and picked up their flyer. A 2-stroke Yamaha 90 is awful tempting, but I'd really like a DF115.
                              \'72 Mako 17, Suzuki 140 FOR SALE[br]\'74 Mako 19B Project FOR SALE[br]Seabird 21 Project FOR SALE[br]San Juan 28 sailboat [br]Wake, VA[br][IMG]

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