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  1. #1
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    lightweight flywheel?

    I understand why a lightweight flywheel would be a good thing on a race engine or even an engine on a high performance hull like a Viper or VKing, or SS2000 etc...but what about a bass boat? I can see where the reduced rotating mass would allow the engine to rev quicker and be a little more responsive but in my mind I think the heavier flywheel would be beneficial to a bass boat or cruising type boat for the increased inertia once you got the engine RPM up, the weight would help keep it there which would in turn make it easier for the engine to keep a heavy boat on plane. ? Am I on the right track with this or am I thinking too hard about it?


    Slimm
    Hire the handicapped, we're fun to watch

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    Easier on upper bearings......

    Jay
    Jay @ JSRE


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    Quote Originally Posted by Jay Smith View Post
    Easier on upper bearings......

    Jay
    Just curious as I hear this a lot but if its balanced why would it be easier on the bearings? I would think balanced as a complete rotating assembly would be the easiest on the bearings. Thats what they did to mine at Falicon when I sent it off. The balanced it all.
    13' Biel tunnel AKA "Flight Risk"
    13" Modified Yamaha V4 - 101 mph

    21' Paramount
    Mercury 300 Promax

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    What is the likelihood that a light weight flywheel will crack?
    18 Charger DL, 2.6L Yamaha.

  5. #5
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    The flywheel rotating acts like a gyroscope,and fights changes in angle,just as a side grinder fights changes in angle when it's spinning.Try it,then realize the fighting force(of directional change) of the spinning object is in direct proportion to the weight of the object.So,when the boat tips from side to side the upper crank bearing has hundred of pounds of side stress applied to it holding the flywheel at the same angle as the boat,the flywheel weighing many times more than the 4 ounce grinding disk. Not as much of an issue on a tunnel boat...more stable,so less stresses,Chris

  6. #6
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    Quote Originally Posted by Chris Carson's Marine View Post
    The flywheel rotating acts like a gyroscope,and fights changes in angle,just as a side grinder fights changes in angle when it's spinning.Try it,then realize the fighting force(of directional change) of the spinning object is in direct proportion to the weight of the object.So,when the boat tips from side to side the upper crank bearing has hundred of pounds of side stress applied to it holding the flywheel at the same angle as the boat,the flywheel weighing many times more than the 4 ounce grinding disk. Not as much of an issue on a tunnel boat...more stable,so less stresses,Chris
    Hence the flexplate

  7. #7
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    Quote Originally Posted by Chris Carson's Marine View Post
    The flywheel rotating acts like a gyroscope,and fights changes in angle,just as a side grinder fights changes in angle when it's spinning.Try it,then realize the fighting force(of directional change) of the spinning object is in direct proportion to the weight of the object.So,when the boat tips from side to side the upper crank bearing has hundred of pounds of side stress applied to it holding the flywheel at the same angle as the boat,the flywheel weighing many times more than the 4 ounce grinding disk. Not as much of an issue on a tunnel boat...more stable,so less stresses,Chris
    Bingo! This is why it's easier on top bearing and crank and reason to run a light wheel. I don't believe the motor will accelerate any faster
    Erik Kiser

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    Quote Originally Posted by patchesII View Post
    Bingo! This is why it's easier on top bearing and crank and reason to run a light wheel. I don't believe the motor will accelerate any faster
    It might but a heavy propeller will nullify that effect

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    Quote Originally Posted by patchesII View Post
    Bingo! This is why it's easier on top bearing and crank and reason to run a light wheel. I don't believe the motor will accelerate any faster
    Erik,I would agree with "much faster"or"noticeably faster",but not any faster...placing an object in motion wether it's rotation,linear,or reciprocation requires energy...heavier objects require more energy than lighter ones to achieve the same speed.For what it's worth that goes the same with deceleration as well.Lightened flywheels are brought up to speed with less energy than heavier ones,so with the same energy applied the result is quicker accelleration.This will hold true for most everything...pistons,rods,cranks,propellers...boats...
    I also agree that in some cases parts are lightened to the point of weakness and failure,so as usual too much of a good thing isn't always great,but I'm sure you've won a race by 6 feet one time or another...realize that 2 more quarts of fuel in your tank (4 pounds)and you would have lost,It's all the little things that add up,Chris

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    Data by some pretty high end telemetry in our boats tell otherwise on some old tried and true modifications. I've spent whole days testing and changing things. I absolutely think the lighter flywheel has merit, just not as a performance gain. Disclaimer- I'm only talking about the stock 16 amp Drag flywheel versus the lighter versions like Diamond and PPE and this is my educated opinion.
    Erik Kiser

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    Quote Originally Posted by patchesII View Post
    Data by some pretty high end telemetry in our boats tell otherwise on some old tried and true modifications. I've spent whole days testing and changing things. I absolutely think the lighter flywheel has merit, just not as a performance gain. Disclaimer- I'm only talking about the stock 16 amp Drag flywheel versus the lighter versions like Diamond and PPE and this is my educated opinion.
    on a light race boat sure...

  12. #12
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    I respect your opinion,you have a lot more real time testing than I.Repeatability on the Dyno is usually 2-4 percent with very similar conditions,so you can loose or gain more accuracy it seems to me when you unbolt that powerheas and run it on a boat...many more variables.So,I am basing my opinion on faith in physics...If you were to try a 40 amp iron flywheel you agree you might(would) see a difference?So,at what point does a small amount of weight at high speed carry no energy?A little bullet can carry a lot of energy...just sayin.Not being a ah over a point,just looking from a physics perspective,can't be ignored,Chris

  13. #13
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    While building hot rods and rat rods we often change things on the front end of some of these old cars and I have actually used the gyroscope reference when making changes to the front end of a few rat rods. Sometimes I think too hard about things and in this instance, not hard enough. I never thought about the flywheel performing like a gyroscope and the load it would put on the top bearing, among other components, of an outboard....simply never entered my mind. I love seeing conversations like this because I always learn, and I like reading other peoples' views and opinions.
    Thank you all for your information and the time you took to add your thoughts, opinions and facts.

    Slimm
    Hire the handicapped, we're fun to watch

  14. #14
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    take the front wheel off your bicycle, hold the axel and spin the wheel....
    then try to change the axel postion

  15. #15
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    Quote Originally Posted by powerabout View Post
    take the front wheel off your bicycle, hold the axel and spin the wheel....
    then try to change the axel postion

    I have done that many many times when I was young. It fascinated me from about the age of 8 or 9. I would take the wheel off and sit spinning it in my hand and try to understand why it acted like that. I also sat it on the side and would spin it and watch it balance on the axle shaft. My dad would just shake his head and wonder why I was taking my bikes apart and playing with the individual components instead of just riding it. LoL

    Slimm
    Hire the handicapped, we're fun to watch

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