Even so, radius is still related to moment of inertia. So my original post was correct. 
There, this argument is done… no more… physics is over… never again…
:roll: god dammit end this.
Pete i’m going to take this really slowly.
~ The reason the e-test dyno meter cannot go beyond 130 hp is because the angular velocity is to great for it. Y/N
~ Creating a larger radius will slow down the angular velocity of the machine, similar to sticking your hands out when you are spinning, … [try it at home, spin and increase your radius by sticking out your hands]. Y/N
~ Moment of inertia is related to both Mass and Radius, but in this case the mass of the rollers is not the problem, agree? Y/N
If you said Y to all 3, then nik is right!
And P.S. the way a dyno works has nothing to do with mass the dyno puts a resistense on the rollers, similar to force of friction, and measures the force to slow down the engine, so mass doesnt matter … Y/N
consider this a bonus.
Let me make it more clear.
Is moment of inertia directly related to radius? Y/N
Given: I = 1/2MR^2 (where I is the moment of inertia)
Answer: Y
Does increasing the radius increase the moment of inertia? Y/N
As R^2 is in the numerator, as it increases, I must increase as well.
Answer: Y
So therefore, the e-test dyno has too small of a moment of inertia (too small of radius) Y/N
Radius too small = Moment of Inertia too small
Answer: Y
Is Pete’s first post correct (yes, the one Nik started bitching about)? Y/N
Answer: Y
BTW the answer is N, thats what the arguement is about.
If the M=9 and R=5, is that same inertia as M=25 amd R = 3 yet radius is different.
Moment of inertia has the same magnitude but the radius’s are different and the dyno doesn’t deal with mass, so if radius changes the moment of inertia changes but so does mass so moment of inertia is not directly related to radius because as seen in my example, there are other variables that can be used that give the same magnitude.
Moment of inertia has the same magnitude but the radius’s are different and the dyno doesn’t deal with mass, so if radius changes the moment of inertia changes but so does mass so moment of inertia is not directly related to radius because as seen in my example, there are other variables that can be used that give the same magnitude.
Yes, but you are changing mass in the process.
Look at it this way:
An e-test dyno has rollers of small mass and small radius.
A performance dyno has rollers of large mass and large radius.
The moment of inertia of the performance dyno is greater then that of the e-test dyno. Likewise, the e-test dyno has an insufficient moment of inertia.
but its not due to the mass, it needs a larger radius, mass is a consequense. An ideal dynoer, the rollers would have little mass becuase the point of the dynoer is to manipulate the rotation and oppose force and the mass makes it harder. There is a possibility that the magnitudes between a crapy etest dyno with small radius and medium mass, will be the same as a professional dynoer with larger radius but less mass (due to better roller material). Therefore the moments of inertia are the same, never changed yet because of the radius difference one works more precisely than the other.
^^^ approved by matt tham.
You cannot argue this point, because it is true.
If the M=9 and R=5, is that same inertia as M=25 amd R = 3 yet radius is different. look at this example again, the radius has changed but the moment of inertia is the same.
MOMENT OF INERTIA IS THE SAME BUT THE RADIUS IS DIFFERENT!!! THIS EXAMPLE IS PERFECTLY PLAUSIBLE AND THE ONE WITH RADIUS 5 WILL HAVE A MORE ACCURATE ANSWER, AND MOMENT OF INERTIA HAD NO EFFECT ON THE EXAMPLE, ONLY THE TO INDEPENDENT INTERNAL VARIABLES.
^^^
Ideal dyno??
Do we live in an ideal world? Do we ride on friction-less bearings?
No. There is no way a dyno roller will have less mass, regardless of materials.
E-test dyno:
Performance dyno:
Notice the difference in the size of the rollers. For the moment of inertia to be the same, the mass of the performance roller would have to be incredibly small. And by incredibly I mean impossible. The mass of the performance roller will be greater. Thus, the moment of inertia will be greater.
Therefore my INITIAL statement of insufficient moment of inertia is CORRECT. Regardless of what the theory is, in the real world the mass is greater, and so the moment of inertia is greater.
Thats all I’m proving, that my first statement was correct.
- Dyno
OR
- RSM
too…much…physics…brain…hurting :bash:
Yeah but we can find solutions for questions using theory, it is possible for my example to work: for example(very extreme):
etest rollers made of diamond (densest substance), and the dyno machine made of carbon nanotubes (lightest). then what i am saying is possible, and in theory mine is perfectly sound, and with extreme conditions, it is possible. Another more possible example, the waterloo race car is dynoed, it doesn’t weight much, we put it up to a etest dyno with rollers made of steel, or pro-dyno with rollers made of hollow plastic, they both can support the weight of the kart, and my senario is now plausable.
I’ll i’m trying to do is prove my initial statement is right, adnd btw yours is right but no completely. Look at me example DAMMIT! the theory works!!
Moment of inertia is key for defining rotation, but the arguement is about why the etest dyno can only go to 130 hp, and how this can be solved, i feel my exmples and theories shown prove that it is the radius of the rollers that give a more precise magnitude, moment of intertia is effected but not nessarily (see examples 1.0), and not enough to state that it is the problem and the solution.
Thusly, rain stop so we can go drifting.
========
example 1.0:
If the M=9 and R=5, is that same inertia as M=25 amd R = 3 yet radius is different. look at this example again, the radius has changed but the moment of inertia is the same.
We are both correct then.
Yes your theory is sound. But I’m also considering the real world, where rollers are not made of diamond. :lol:
In which case the rollers on a pro-dyno are heavier, and the moment of inertia is greater.
We’re both right in our own sense… and it only took us an afternoon of posts.
Well its better than studying algebra.
I think yours would be super completely correct to the extreme if you would have defined that it was due to the radius.
Because in theory and in very extreme applications there is the situation where the moment of inertia does not change where the radius does.
I feel mines a slight bit more right than yours but i really dont care anymore, yay both right.
And i’m not surprised the F’n dynos aren’t made of diamond, they cost so much to get done!!!
Thanks to everyone who took the time to reply to my query. I guess I accidentally spark a dyno debate. All in all some good information, Thanks.
My experience was that when I bought it used, I had test driven quite a few, the stock 16 valve engine was better than the 12. I picked the one that had the most torque, but it also had the lowest mileage tested.
When I added the cone filter it mostly got louder and not much faster. When I added the chip and header together there was a big difference but the mileage sucked. After backing off the chip settings I actually got better acceleration and cold performance with a comparable reduced mileage, but better highway mileage at equal cruising speed. The exhaust and Catalytic added noticable power when higher now useful rpm was accessed. I then switched to a bigger resonator, to reduce noise for a minimal power loss. The underpulley and no A/C did not do much to top end power but made the car much more responsive to a push on the pedal. Lowered suspension was huge. In short, every change was noticed. Thanks, Dave