Re: More Performance [lightened flywheels]

[Brett P VanSprewenburg <brettv@rocketmail.com>]

---Kevin <aventari@cts.com> wrote:

> 
> For the clutch, I'll tell you exactly what I just did. First I had the
> flywheel resurfaced, then I had one machine shop lighten it and another one
> balance it for me. You can either spend $120 plus core plus shipping for
> Velocity's unit(where they take 5lbs off.. I dont believe that), or you can
> have the shop machine off the whole weight ring for 40 bucks and pay 25 or
> so to have it balanced. The weight ring is the thick part(with hole drilled
> in it probably) that's outside of the teeth. It's probably 1.5cm wide and
> 2cm thick. 
> The weight ring is usually the part you have to drill holes in to balance
> it, so my machine shop had to drill out of the verticle part that is
> between the teeth and the hole in the middle. It's kinda had to explain! :)
> I haven't installed it yet, so i cant say how much performance I gained,
> but to start with, the 210mm flywheel was: 11 lbs (it might've been 13, but
> i dont think so)
> after the lightening and balancing process it got down to: 8 lbs, about 30%
> wieght reduction,(the flywheel is lighter than the pressure plate now!) and
> remember that this weight is on the outside of the rotating mass, so it
> helps doubly so! Each pound you take off the rotating mass will net you
> approx. 2.7 hp (according to unorthodox racing) 8 hp is not bad!!

> Kevin Fry 
> aka aventari
> icq#21583385

For the record, decreasing rotating mass (like a lightened flywheel) adds
zero horsepower and zero torque to your engine.  I can almost hear the
hairs raising on peoples necks. :)  Think about it, changing the amount
of mass that the crank is spinning doesn't change the specific power
output of your engine.  However, lightening the rotation mass does change
a couple of things...specifically, how _quickly_ your engine will reach
a certain RPM/torque value.  With less mass to spin, the engine logically
will spin up quicker, and is able to accelerate faster...however, NO
additional HP is being generated...it's just that LESS HP is being wasted
spinning 'dead' weight and more of it is being spent to accelerate the
vehicle.   Chop off 4 pounds from the flywheel of the 90hp JH and guess
what, it still produces 90hp...but a tiny bit _more_ of that HP reaches
the wheels, less of it is wasted spinning heavy things on the way to
the tires. 

Unorthodox is playing with words when they say it adds HP, what they're
really saying is it frees up hp...and I think their estimate may be a 
little optimistic, due to the fact that they have no idea what the radius
arc of that 1 pound described, and cannot calculate HP freed reliably. One
pound at the outer edge of your tire has more rotational weight (not mass),
then one pound at the lug nuts.  

==Brett
 
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