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Re: Lighter flywheels

To: <spitfires@autox.team.net>, <rolling_rock_12@yahoo.com>
Subject: Re: Lighter flywheels
From: "Nolan Penney" <npenney@mde.state.md.us>
Date: Thu, 18 Oct 2001 07:21:09 -0400
You promptly find yourself in the "good enough" quagmire.
Theoretically, all stock components are "good enough" to
bolt up to each other and work.  That is how the engine
manufactures slap them together on the assembly line.
Stacks of flywheels, cranks and such, stuffed into the
block, and away you go.  Depending on how well things
happened to come together, you either get a really smooth
engine, or maybe a somewhat rough one.  But in any case,
it will be "good enough" to roll out the door.

So, can you simply bolt on a seperately balanced flywheel
and have it work like the factory did in building stock engines?  
Yes.  But it will be in the "good enough"classification.  If 
indeed that is good enough for you, then you're fine and 
quite happy with the results.  

Now a GT6 engine is an inline 6, so it tends to be inherently
rather well balanced by that virtue.  However, Triumph
isn't noted for balancing engines well when they slapped
them together.  The Spitfire engines being a very notable
example of that, especially the later ones.  Triumphs idea
of "good enough" is quite a bit lower then most of us would
like.  

So, if you're planning on really screaming this engine,
it probably would do you well to have the entire rotating
assembly balanced and optimized.  It's going to cost you,
but it'll be cheaper then breaking a crank and throwing
it through the block.  But on the other hand, if you're just
warming the engine up as a street car, and you're not going
to scream it constantly, then simply using an individually
balanced flywheel will probably be perfectly adequate
for your needs.  FWIW, I'll probably bolt my lightened flywheel
onto my Spitfire this winter, without balancing the entire
rotating mass.

As for the harmonic balancer, if the GT6 uses the rubber
ringed body that the american engines typically used, it's
really not a harmonic balancer as much as it's a damper.
In which case, it really doesn't matter about lightening
the flywheel.



>>> mark holbrook <rolling_rock_12@yahoo.com> 10/17 8:56 PM >>>
I am about to buy a lighter flywheel for my GT6 that
is about 8 lbs lighter than stock.  Before I do this I
want to know if it is going to through the engine out
of balance.  I know that new cars have the harmonic
balancer very close in balance with the flywheel. 
Will a lighter flywheel with an uncalibrated harmonic
balncer through off the engine balance?

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