Flywheel swap

[gmorgan]

I have a stock 225 Super Mag except the limiter has been raised to 7,600 RPMs. It is on an XB2003. Right now in cool weather it turns an offshore cut chopper 7,250 RPMs at 93.95 MPH loaded to fish with one man. I am 63 and don't fish all day anymore, so battery charge isn't as big a problem as it once was.

I used to drag race 2.5 motors on an Alison drag boat. In my opinion one of the best mods I ever made to the motor was to lighten all the reciprocating weight, rods, pistons, crank and flywheel.

If I replace my 40-amp charging system with a 16-amp and use a Diamond lightened 16-amp flywheel, what performance will I gain? I know it has to rev slightly quicker and put less strain on the crank, but how much speed will it pick up?

I see Simon says if they lighten the 40-amp flywheel you will pick up 1 to 3 MPH.

 

[Dave Hensley]

Mr. Gary I will put this on your bill. The performance gain with a lighter flywheel would be largely in acceleration/de-acceleration of the motor. You might see a slight mph gain but I would think even 1 mph would be optimistic. Once that 40 amp gets up and spinning it will turn the same rpms as a liteweight. You would help the top of the crank live longer but at 7600 rpms that isnt a real issue. You need to scratch that mph itch with one of these 280's I have sitting up here.

 

[michael j giesler]

I think Brendan powers now has a 40 amp light flywheel all his stuff is very well built and a lot of testing is done before it is sold to the public

 

[gmorgan]

I thought surely there were a lot of guys who had tried the lighter flywheel and smaller charging system that could give their real life experience. Either it helps or it doesn't? Anybody else have an opinion?

 

[Jon]

+1 to Dave's comment. Just like with any other motor, you will notice it on acceleration but not really top end. It does not take a significant amount of power to keep a weight spinning once it is at speed. Some Newton guy had a theory about it.

We use 500lb flywheels for power generation and spin them at 60k rpm in vegetable oil - it does not take much power to do so, therefore not a lot of power loss goes into keeping it spinning. If you were pulling an uneven load then you would have a more linear output from the motor, such as with a skiier or something.

 

[RBT]

The difference in hp between a 40 amp and 16 is 1.5 hp. Convert amps to watts to hp.
The difference is in the rotational mass for excel. Never compromise voltage though.

 

[whipper]

So does that also mean a 16 amp flywheel will help decelerate faster than a 40 as well? Given the lesser degree of inertia I would think so?

 

[RBT]

Yes