Flywheels (Was:Re: RS2 turbocharger)

[TM]

Gerard-
You have it slightly backwards- a light flywheel will be very
easy to rev and will drop in revs very quickly. Think of it as
inertia- heavy flywheels have lots of inertia.

I didn't think flywheels had really much to do w/ power output,
but rather that relatively heavy flywheels are used on street
cars so that they are easier to drive and shift- a really light
flywheel would make rev matching rather tricky for shifting.

Taka

-----Original Message-----
From: quattro-admin at audifans.com [mailto:quattro-admin at audifans.com] On
Behalf Of gerard
Sent: Monday, June 10, 2002 3:47 PM
To: Nate Stuart
Cc: quattro at audifans.com
Subject: Re: Flywheels (Was:Re: RS2 turbocharger)


> That sounds awfully backwards to me. A hevier flywheel will 'contain'
> more energy, and take longer for that energy to be bled off by the
> compressions in the cylinders and frictions in in the engine. A
> lighter flywheel can 'contain' less energy, and bleeds it off much
> sooner, so the revs drop faster.
>
> Spin a 50 pound tire on a hub and stop it with your hand, then spin a
> bicycle tire and stop it in the same fasion, you'll get the idea. In
> generall a lighter flywheel will get the revs up and down quicker at
> the loss of 'smoothness' where the heavier ones will take longer to
> rev up and to drop revs, but they smoothen out (slow down) rapid
> changes in torque.
>
> Hmm, hope I got some of that right.....

It makes more sense than the current theories bouncing around my head.
The mention of smoothness is what I am thinking of in the Opel machines
I've been in over here. Sometimes they rev up a bit, then take forever
to fall in rpm. Perhaps I do have it backwards and in fact those engines
have very heavy flywheels instead of light ones.

So, the question now is which wheel is better for low end grunt?

If one were to lighten the flywheel of a stock MC what would the results
be in terms of torque and power distribution if you were, say, running
stock everything on the car except the flywheel?

G.