balancing.

[mr.utility at highstream.net (mr.utility@highstream.net)]

Okay, round two...

Quoting Dan Bubb <jdbubb@ix.netcom.com>:

> 
> >  It takes energy, to save enregy...
> 
> You're going to have to explain this. I know it takes money to make money,
> but can't imagine how expending energy allows you to save energy
> 
It was more of a philosophical point, an aside...  But for example, the fact 
that IF we had a lot of hydrogen burning cars on the roads to SAVE fossil 
fules, we would have to greatly increase our burning of coal (read FOSSIL 
FUELS) so that we could electrolize hydrogen from water (as there is no 
natural source for hydrogen)...  If you do not get that, let's drop it...  The 
original argument is more important...

> >   As you are cruising on the highway, it takes less effort to stay at a 
> >constant speed with a stock flywheel, because you have built-up inertia... 
> 
> >Inertia is defined as the resistance to change it's present state of 
> >motion...  In this case, if the flywheel is spun at 4K, it is going to
> resist 
> >a change in speed, either up or down, IF it has more weight to it, yes? Then
> 
> >that inertia will in fact save you more mpg, at a cost of mph...
> 
> So, if I understand this correctly, greater inertia helps you to maintain a
> constant speed better and because of this your throttle is more constant and
> therefore you get better mileage?

To be more specific, this should read ---"greater inertia helps you to 
maintain a constant speed more easily, and therefore if your throttle is 
constant, the inertia of a weighted flywheel will be higher than a lilghtened 
flywheel, therefore more mpg."  

 Well, I can't argue with that but think
> it's such a small change you're never going to be able to measure it. 

I did not say it was a huge drop, I just said that it would happen...

The
> flywheel may represent a significant amount of the rotational inertia of the
> engine, but not a significant amount of the inertia (both linear and
> rotational) of the whole car, especially in the higher gears where the engine
> is only turning 3-3.5 times faster than the wheels.

True, but the whole car does not push itself along, the engine does...  And if 
you improve the ability of the engine to maintain a given speed, then IF it 
maintains a given speed, the efficiency is higher...  BTW, the whole car does 
not have any rotational inertia to speak of, unless it is rolling end over 
end...  :-)

> >From a purely physics point of view, baring frictional effects, if a mass is
> at a constant velocity (linear or rotational) it takes no energy to maintain
> that velocity. 

Do you engineer rockets or something?  We are on earth, where friction is 
king, and gravity its' gueen...  If that were true, I could coast from 
Oklahoma City, to Dallas without any trouble...  Even if I do not include 
friction, there is still gravity, prevailing winds, etc...  I am speaking of a 
real world scenario here, or trying to...

Clearly it takes less energy to accelerate a lighter mass, but
> to maintain a constant speed requires no energy input so there is no
> difference between a light flywheel and a heavy one.

Ummm, like, what?!  We are talking about cars, not space ships...  It does 
take less energy to accelerate a lesser mass, which is why we are talking 
about all this mess...  To maintain a given speed DOES take energy, as this is 
the real world we live in, not space...  

> If you take into account frictional effects, bearing friction and aerodynamic
> drag, the lighter flywheel will have less bearing friction (insignificant)
> and the same aerodynamic drag (for all practical purposes), so, again, there
> is no practical difference between a light flywheel and a heavy one as far as
> energy input required to maintain speed and no difference in MPG.
>
WHAT!?!  Umm, no...  Take an 2.0 off the line in Wolfsburg today, drive the 
snot out of it for 200K, and you will have a wear factor (what ever that is), 
of 1.2 say...  Now, take an identical engine, under identical conditions with 
the exception of a lightened flywheel, and you will have the SAME WEAR 
factor...  WHY!?!  Because both flywheels are balanced!  Neither will have any 
effect on bearing wear!  The only way  there would be less bearing wear is if 
the lightened flywheel magically removes the amount of bearing surface in the 
engine, which it cannot do...  (screwy)

 Overall, I'd expect to see a slight increase in MPG from a lightened flywheel
> simply because you're accelerating less mass.
> 
Depends...  What amount of time are you accelerating?  What amount of time are 
you maintaining a given speed?  Answer these questions, and you will have your 
answer, either way... 

> >   Do you know how heavy a Diesel flywheel is in comparison to a gas 
> >flywheel?  Part of the reason is that they have a higher mpg is because of
> the 
> >higher inertia they have once up to speed... 
> 
> I disagree. Diesels get better mileage due to the higher energy content of
> diesel fuel and the more efficient diesel cycle. The heavier flywheel is
> required because of the significantly higher CR of a diesel engine. More
> energy/inertia is required to get the engine through the compression stroke
> and maintain decent idle quality doing so.
> 
Re-read....  PART of the reason, not THE reason....  PART, say it with me, 
PART, Part, part....  There, I feel better...  :-)


> >  The reasons you cited for having weight on the flywheel are good reasons
> as 
> >well, but they are not the only ones...
> 
> Sorry, your original statement that a heavy flywheel would increase highway
> fuel mileage implied that was the Primary reason for a heavy flywheel which
> is incorrect.
> 
That is not what I said...  I said REDUCING the weight of the original 
flywheel would DECREASE your fuel mileage on the highway...  Patrick has 
agreed with my findings, he too has lost some mpg, at the gain of power...

> >David
> 
> >PS  And while I read the Vortex quite a bit, I weigh that against hands-on 
> >experience, as well as reading good technical sources (read that 
> >as 'accredited'), as well as long conversations with a good friend of 13
> years 
> >who has been a mechanic for almost 40 years...  The one thing I will promise
> 
> >each and every one of you is if you can prove me wrong, I will admit it, 
> >period...  I don't know it all, nor do I pretend to (hopefully) :-)  I can 
> >only ask that if you do not agree/understand, please ask questions...  I
> have 
> >not insulted anyone here, nor will I throw jabs at someone, even if I 
> >disagree, but especially if I do not understand...  I am here to learn, and
> to 
> >share.  I thought that was that this list was for...  Did I misundestand? 
> 
> Ya know, I'm an engineer and I've spent way too much time thinking about and
> working on cars.

An engineer of what?!?  Perhaps instead of thinking about cars, you should 
instead work on them , and experience a few things...  You seem a bit too far 
removed from working on them daily, as I do...  And are you 'implying' that 
because you are an engineer, and I am not, that I am wrong?  I may only have 
two diplommas on my wall, but let's face it...  The most novel invetions come 
from those who were not trained to 'know better'...

 Maybe, I'm overly concerned about trying to help make the
> Scirocco list technically correct and, hopefully, a huge step up on some of
> the laughable statements made on Vortex.
> 

I applaud you on that, if that is what you are attempting to do...  I just 
hope that you are looking for the 'truth' in its broadest terms, and not just 
in yours... 

> But, whatever. 
> 
> 
> 
No, not whatever...  I apologize if I seem heated, but you have 'implied' that 
I am merely regurjitating what I have read on Vortex, which is not the 
case...  I am insulted by that, as I have not brought in any outside comments 
into this discussion, as I don't know you, nor do you know me...    I ahve not 
said, well, you suck, because your idea makes no sense...I have stuck to the 
point here as much as I can, and I hope that you can do so as well...  Anyone 
can sling indirect insults if they do not understand, it takes someone of real 
character to try to understand something that they initially do not agree 
with...

Now, please stick to the point at hand, and I will not be insulted...

David

Rant mode, off....