Flywheel or Flexplate

[Moneypitt]

This subject has been bounced off of just about every builders opinion. I have stated before, and I'll say it again. The PS boat is 13.1;1. Right now, because it has a 427 crank in it, we're using an aftermarket aluminum flexplate. This one lost the ring gear the first time I winged it on the trailer. I fixed it and we used it for awhile in the early 90s. And again with this set up. However, we have also used, without any problems whatsoever, a bone stock GM external flexplate on the 454 cranked motors. Never had any problems with starter engagement using a stock GM starter with a P/G nose. I have seen so many other racers fail to start using the high dollar aftermarket flywheels/flexplates and the high dollar aftermarket mini/hi torq starters. It is true that a converter adds alot of strength to the flexplate, but in a boat it is just a starter ring, period. There is no power suppied through the plate. Considering the mass you have to move, any weight saving on a rotating assembly is a good thing. Also, you're not trying to ease a vehicle from a dead stop while letting the clutch out, so you don't need the momentum of a heavy flywheel to prevent stalling the engine. Rotating mass = less is better. The most important thing in a starter/starter ring engagement is a stout battery to spin it up without laboring. The rest is all good.........Now if you're running a MOPAR, you have to use a flywheel because the starter ring on the automatics is on the converter, not the flexplate............MP

[Duane HTP]

Flex plate is the recommended way to go. Just don't go to your local salvage or dealer and buy a regular car flex plate. Like said above they can Flex without the converter bolted to them. This usually results in starter problems sooner or later. Buy a good SFI or the thicker flexplate that is used in the patrol cars. A lot of people don't realize that a starter works harder in a jet boat than it does a car because it not only has to start the engine, it has to turn the pump shaft, the drive line, loaded impeller and move water all at the same time. Running a flex plate in a jet boat is not harder on the engine than the flywheel because the pump shaft, drive line, and impeller serve as the flywheel. Just use a GOOD flex plate. Pioneer makes a good thick one at a reasonable price for most applications.

[396_WAYS_TO_SPIT]

Use an aluminum flywheel! It is light and it won't flex when the starter engages and rip the teeth off. If you don't have a nasty motor, either will work. A flexplate in a car is no problem cause the torque convertor is bolted to it and provides rigidity for the ring gear. The fool that I bought my last alum. flywheel from at a local swap meet laughed to his friends that he screwed me because the flywheel needed to be surfaced and someone told him that it couldn't be done,(wrong again). He "got" me for $10.00 on it. Its still in the boat 4 years later. Yup, I was "got". TIMINATOR
Sounds like you got him Thats a smoking deal on an aluminum flywheel.

[SmokinLowriderSS]

Use an aluminum flywheel! It is light and it won't flex when the starter engages and rip the teeth off. If you don't have a nasty motor, either will work. A flexplate in a car is no problem cause the torque convertor is bolted to it and provides rigidity for the ring gear. The fool that I bought my last alum. flywheel from at a local swap meet laughed to his friends that he screwed me because the flywheel needed to be surfaced and someone told him that it couldn't be done,(wrong again). He "got" me for $10.00 on it. Its still in the boat 4 years later. Yup, I was "got". TIMINATOR
Yep, can't complain about THAT deal. LOL :rollside:

[Taylorman]

Interested in doubling your money on that flywheel?

[Klass Klown]

This subject has been bounced off of just about every builders opinion. I have stated before, and I'll say it again. The PS boat is 13.1;1. Right now, because it has a 427 crank in it, we're using an aftermarket aluminum flexplate. This one lost the ring gear the first time I winged it on the trailer. I fixed it and we used it for awhile in the early 90s. And again with this set up. However, we have also used, without any problems whatsoever, a bone stock GM external flexplate on the 454 cranked motors. Never had any problems with starter engagement using a stock GM starter with a P/G nose. I have seen so many other racers fail to start using the high dollar aftermarket flywheels/flexplates and the high dollar aftermarket mini/hi torq starters. It is true that a converter adds alot of strength to the flexplate, but in a boat it is just a starter ring, period. There is no power suppied through the plate. Considering the mass you have to move, any weight saving on a rotating assembly is a good thing. Also, you're not trying to ease a vehicle from a dead stop while letting the clutch out, so you don't need the momentum of a heavy flywheel to prevent stalling the engine. Rotating mass = less is better. The most important thing in a starter/starter ring engagement is a stout battery to spin it up without laboring. The rest is all good.........Now if you're running a MOPAR, you have to use a flywheel because the starter ring on the automatics is on the converter, not the flexplate............MP So what you are saying is the extra weight (in the form of a flywheel) would not help you keep the momentum(rpm) up in the motor into a turn?? I understand your point yet do you mine?

[wsuwrhr]

Now if you're running a MOPAR, you have to use a flywheel because the starter ring on the automatics is on the converter, not the flexplate............MP
Damn Mopars.
Brian

[Moneypitt]

So what you are saying is the extra weight (in the form of a flywheel) would not help you keep the momentum(rpm) up in the motor into a turn?? I understand your point yet do you mine?
What type of boat, and what type of turn.......Vdrives have NO problem keeping the Rs up around a turn, IF the driver is on the right pedal while he's on the left pedal. However, the west coast single pin turns usually require backing off and hitting the plate. Then getting the Rs back up is the heavy flywheel issue, more mass= slower Reving. As I said, we're not talking about letting out a clutch to move a vehicle. Quite frankly, I can see no reason what so ever to add additional weight to a rotating assy in a boat, regardless of the drive type.........MP

[Klass Klown]

You obviously NO NOTHING about torsional harmonics. Case proven..

[Moneypitt]

You obviously KNOW nothing about elementry school english........torsional harmonics.......hmmmmmmm, lets see a harmonic is a vibration, so the more weight you spin up has more harmonics? I didn't think vibration was something you wanted in a rotating mass. I remember the Ford Courier trucks, so under powered they had to put a 40 lb flywheel in them to keep from stalling the motor when you let the clutch out......Now, explain to me what advantage this additional weight has on a rotating mass in a boat. MP