Flywheel vs flexplate
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Flywheel vs flexplate

  1. #1
    Cantard 71hallett's Avatar
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    Default Flywheel vs flexplate

    Educate me...pros / cons exc.
    Quote Originally Posted by gn7 View Post
    It would be a balmy 85* in Steel's shop if he would move a little faster

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    The Man cordog009's Avatar
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    Seems like basically there isn't much of an advantage to running one over the other. From what I've seen there's really no reason to switch from one from the other. Basically it's just been stick with what your setup came with or if you're starting from scratch, pick one and set your engine and driveline up accordingly. On a street or race car, the only reason to switch flywheels is to go to a lighter one to allow the engine to rev quicker. In a boat the engine won't know the difference between the two on the back end of it.


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    Cantard 71hallett's Avatar
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    reason I am asking is that its for my 3pt hydro where the prop is in and out of the water constantly.
    Quote Originally Posted by gn7 View Post
    It would be a balmy 85* in Steel's shop if he would move a little faster

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    Senior Member GT Jets's Avatar
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    Quote Originally Posted by 71hallett View Post
    reason I am asking is that its for my 3pt hydro where the prop is in and out of the water constantly.
    Aluminum flywheel, less centrifugal inertia and ligher weight than an iron flywheel, yet much stronger than a flexplate.

    IMHO flexplates are only used because they are way cheaper than an aluminum flywheel...

    GT
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    Quote Originally Posted by Quickjet View Post
    Put a 300 on the back of it, Flywheel it and a nosecone. $15,000 later you'll have a 65 mph pile of shit......

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    Senior Member Bubbletop409's Avatar
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    The drive line adapter " sandwhiches " the flex/flywheel between itself and the crank drive flange so I don't see where it would make any diff, if the prop spends a lot of time biting air a heavy wheel would tend to keep the engine from going to the moon as quickly as it would with just a flex plate.
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    Cantard 71hallett's Avatar
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    Driveline is run of the front crank snout.
    Quote Originally Posted by gn7 View Post
    It would be a balmy 85* in Steel's shop if he would move a little faster

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    Senior Member GT Jets's Avatar
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    Quote Originally Posted by 71hallett View Post
    Driveline is run of the front crank snout.
    Aluminum, less torsional stress on the crank

    GT
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    Quote Originally Posted by Quickjet View Post
    Put a 300 on the back of it, Flywheel it and a nosecone. $15,000 later you'll have a 65 mph pile of shit......

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    Cantard 71hallett's Avatar
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    Quote Originally Posted by GT Jets View Post
    Aluminum flywheel, less centrifugal inertia and ligher weight than an iron flywheel, yet much stronger than a flexplate.

    IMHO flexplates are only used because they are way cheaper than an aluminum flywheel...

    GT
    So if I went with the aluminum flywheel it would help the engine from zingin up on me?
    Quote Originally Posted by gn7 View Post
    It would be a balmy 85* in Steel's shop if he would move a little faster

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    The Man cordog009's Avatar
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    I assume the prop is in and out of the water on the upper RPMs..if so the engine already has enough momentum that the difference between steel and aluminum won't matter once the engine has already accellerated up into the higher end of the rpm range. Kinda sounds plausible to me anyway if that's when it's happening.


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    Senior Member cave's Avatar
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    Paul from what I've been told is this. Flex plates tend to have a wobble in the extreme rpms. Where a solid aluminum Flywheel is solid thus less wobble. Where this wobble can take place I don't know. I run at around 5600. I kept my flexplate. If I were to run at 7k I'd pick up a flywheel. 3 engine builders told me this. Most of the V drives I've seen here at the local pond run the solid flywheel.
    Takin it home

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    Cantard 71hallett's Avatar
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    Quote Originally Posted by cave View Post
    Paul from what I've been told is this. Flex plates tend to have a wobble in the extreme rpms. Where a solid aluminum Flywheel is solid thus less wobble. Where this wobble can take place I don't know. I run at around 5600. I kept my flexplate. If I were to run at 7k I'd pick up a flywheel. 3 engine builders told me this. Most of the V drives I've seen here at the local pond run the solid flywheel.
    Thanks Cave. This has been on my mind. This engine will spend most of its time in the 6500 to 8500 rpm range.
    Last edited by 71hallett; 09-07-2009 at 07:39 AM.
    Quote Originally Posted by gn7 View Post
    It would be a balmy 85* in Steel's shop if he would move a little faster

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    Senior Member cave's Avatar
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    Quote Originally Posted by 71hallett View Post
    Thanks Cave. This has been on my mind. This engine will spend most of its time in the 6500 to 8500 rpm range.
    If it were me Paul I would get the flywheel. I may end up doing the same this winter.
    Takin it home

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    Cantard 71hallett's Avatar
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    Quote Originally Posted by cave View Post
    If it were me Paul I would get the flywheel. I may end up doing the same this winter.
    Had a dream the flexplate sawed my boat in half. lol
    Quote Originally Posted by gn7 View Post
    It would be a balmy 85* in Steel's shop if he would move a little faster

  16. #14
    steelcomp was here
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    A flywheel would certainly absorb more of the shock from the prop going in and out of the water, help maintain some of the inertia of the engine...if it was between the drive line and the engine. But it's not. Being on the other end of the engine, it might make things worse. What about a fairly large balancer?
    I think for the RPM reasons, I'd run a light weight flywheel instead of a fflex plate as well. There's no torque converter to stabalize the flex plate. Maybe you could build a ring of some sort to replace the torque converter? You like doing stuff like that.
    Last edited by scott foxwell; 09-07-2009 at 09:21 AM.
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