RE: flywheel improvement (and balancing)

["Nick Fonte" <NFonte@domain.elided>]

	In response to your question, Yes I have modified a crank.  I removed
6.5lbs (2.95kg) off my 2.0 from my Alfetta.  The reason for this exercise
was to see the effects of changing the ratio of counterweight to
crank-throw/rod weight.  It proved to be a beneficial experiment.
	But in respect to modifying a crank for inertia reasons, I would vote for
taking it off the flywheel; Let me explain.  I am sorry but I don't have the
numbers in front of me so it will be a little harder to explain.  When we
talk about rotating weight it is the mass-moment of inertia.  The equation
is (mass*radius(squared))/2.  (I'm sure a lot of you know this but anyway).
So after the many, many hours it took to remove the material evenly, and to
balance the crank I did some calculation to see how much more I should take
off the flywheel.  What I found was this:  The moment of inertia of my
modified system (the 6.5lbs modified crank, stock flywheel, and stock front
pulley) it is equal to the moment of inertia of this system... a stock
crank, stock front pulley and .33lbs (.15kg) removed at the outside edge of
a stock flywheel! That is like removing 1/4" of material from the outside
edge. Now of course there is the ring gear and so it would be necessary to
remove the material else where, causing the removal weight to be greater but
you get the idea.

Radius (squared)... It will get you every time.

Happy New Year,

Nick


>BTW! As it is my next project. Does anybody have experience in lightening
>the crankshaft of a 2.0 Alfa engine?

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