<WOB> Reply to Kibort on Flywheels, part 2, PgDn if you don't car e

["Osterbrink, Mark (AFS-Warren)" <Osterbrink@xxxxxxxxxxxxxx>]

> DYNOS will not show this.  a stand alone engine water brake dyno can
though as
> the test would have to be reving the engine over short amouts of time.

No, a brake dyno does NOT measure the effect of lightened engine components
(at
least it's not designed to nor very good at it).  An inertial dyno can
measure
the effects of engine component weight.  -20 points for not grasping a key
concept.  -20 points. 

> >Nascars do it to drop total weight, and increase reving responsiveness
and
> shiftability as they dont use clutches all the time and the engine speeds
> change very quickly. 
> 
> Who ever told you this is either a liar or a fool.  Winston Cup cars have
a
> high minimum weight, and most need to add lead ballast to make it.  They
use
> lightened rotating components to reduce the effective mass that the engine
> must accelerate, looking for any edge they can get in their highly
competitive
> field.  They also (except for a handful of roadraces) don't shift a whole
lot
> in the race.
<Snip>
> >>>>>>>>>>>>yes, the hight and weight is controled, but they can shift
every
> ounce they can off the rotating mass for the above reasons.

What above reasons? Do you mean your previously stated reasons?  To drop
total
weight that can not be dropped? To increase "rev responsiveness" on cars
that
are rarely shifted?  Or do you mean my reason, to reduce the effective mass
that
the engine must accelerate. Hmmm, accelerating out of the pits in 1st, 2nd,
3rd
gears. That's not important in a NASCAR race. Hmmmm, a slight advantage in
accelerating down the straight several hundred times in a 400-500 mile race
that
is many times won by fractions of a second? That's not important either. -50
points for the former, +25 for the later. ?? points.

<Snip>
> An INERTIAL chassis dyno can measure the effects of lightened components.
> Of course a competent engine designer doesn't need to measure it, he will
> calculate the effect of the weight reduction before building the part.
> >>>>>>>>>>>>>>>>>>>>>No, a inertial Chassis dyno like a Dyno Jet cannot
> measure lighted components as the runs are too long in  time to
accelerate..

Yes, an inertial dyno is the ONLY one that can measure the effects of
lightened
engine components. I did not mention a specific brand of dynamometer. Tsk,
Tsk,
missing another major concept.  -30 points.

<Snip>
> GET BACK TO ME AND LET ME KNOW WHAT YOU FIND OUT. IVE DONE THE
CACULATIONS,
> HAVE YOU??

No, no, no, Wile E. I get paid for the correct answers. I don't hand them
out to
snot-nosed kids like you who don't do their homework.

> >Mark Kibort
 
> To answer the original question, it depends :).  What is really important
is
> the mass moment of inertia, which depends on the mass of the object, and
its
> shape. For something simple, like a disk shaped flywheel that is lightened
by
> reducing its thickness, a 5% reduction in mass will produce a 5% reduction
in
> the power required to accelerate it. 
> >>>>>>>>>>>>>>YOU LEFT OUT THE MOST IMPORTANT FACTOR IN THE FOMULA: TIME,
> TIME IS THE CRITICAL ISSUSE HERE. OVER WHAT TIME. On a dyno, it takes
several
> seconds to accelerated the inertial drums that weigh 3000 lbs. the time it
> takes to accelerate that known weight over small periods of time, is the
HP !!

No, time is not a critical factor, assuming it is the same for both the
"normal"
and "lightened" flywheel. The time it takes to accelerate 3000 lbm drum has
nothing to do with it. Reducing the MOI of a flywheel be reducing its
thickness
will produce a proportional reduction in the power required to accelerate it
a
given amount in a given time period. Period. -50 points for, again, failing
to
grasp a key concept.  -50 points.

> If you ignore this factor , you forget that if I was to accelerate the 4
lb
> flyweel or pulley in infinitely small time, the HP would be infinitely
HIGH,
> 100000000s of HP depending on TIME!!!

So, infinity is now defined as "100000000", eh?  The actual power required
is
NOT what I was talking about; I was talking about the reduction in the power
required. My original statement is correct. I would take off more points,
but
what's the point?  You've failed miserably.

> For something like a crank or a wheel, it depends on where the mass is
removed
> , and isn't so easy to calculate. 
> >>>>>>>>>>>Doesnt seem that easy for you .  Do us all a favor, call a math
> teacher or look at an old highschool physics book , You will see that Im
right

Oh, so CALCULATING the mass moment of inertia of a crankshaft is easy for
you?
Sorry, I don't need a math teacher, I know how to calculate it, it just
isn't
easy. And I'm afraid you won't find much help in a high school physics book.
You
know, I'm just too soft. I'll give you a chance to redeem yourself. Since
calculating the MOI of a crankshaft is easy for YOU, we'll give you a little
challenge. If you can provide me with a CLOSED FORM SOLUTION for the mass
moment
of inertia for the moving parts in a 1995 3.0l BMW I-6 (the M-3 engine) by
3:00PM on Friday, January 22, 1999, I will not only change your grade to a
100%,
I will give you $50.


But if you CAN"T do it, you will take your semi-literate, pseudo-scientific,
arrogant little ass off the digest forever.

Deal?

P.S.
Is it me, or do all of his "contributions" take the form of "That
modification
doesn't work. Trust me, I'm an expert. How can you tell I'm an expert? Just
ask
me, I'll tell you! What you need is my electric fan. And my videos.  Oh
yeah,
all the rest of you are morons."?

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