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Old 04-01-2007, 11:11 AM   #46
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This would be a interesting project to see the differences in a RC application.
With the use of telemetry we could possibly gauge if there is a improvement or not.
What would be good guidlines for a exercise like this ?
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Old 04-01-2007, 11:15 AM   #47
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Quote:
Originally Posted by razzor
This would be a interesting project to see the differences in a RC application.
With the use of telemetry we could possibly gauge if there is a improvement or not.
What would be good guidlines for a exercise like this ?
We just need mxwrench to weigh in on this issue. I think he knows the answer and can prove it on the dyno.
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Old 04-01-2007, 11:28 AM   #48
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Quote:
Originally Posted by rmdhawaii
We just need mxwrench to weigh in on this issue. I think he knows the answer and can prove it on the dyno.
the dyno cannot duplicate racing conditions and you cannot draw conclusions from a dyno graph on what will actually happen on the track.

the dyno is meaningless here.
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Old 04-01-2007, 11:29 AM   #49
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Guys, important is what you feel when you drive and as I said before, the car response quicker and faster when I pull the throttle. I dont have any problem with the idle.

I just became my second modified flywheel.
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Old 04-01-2007, 11:34 AM   #50
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Quote:
Originally Posted by cdelong
the dyno cannot duplicate racing conditions and you cannot draw conclusions from a dyno graph on what will actually happen on the track.

the dyno is meaningless here.
All I'm interested in is the difference in torque between a heavier flywheel and a lighter flywheel. That's it. To me, what happens on the track adds to many other variables that I cannot account for - clutch, gearing, drive train, traction, setup, engine, etc.
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Old 04-01-2007, 11:42 AM   #51
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benefits and differences from the dyno and in the car can show us that its worth the effort or not.
Maybe used in conjuction with gearing changes etc. we could a sweet spot for a specific engine combo.
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Old 04-01-2007, 11:42 AM   #52
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Quote:
Originally Posted by jaykay
Guys, important is what you feel when you drive and as I said before, there car response quicker and faster when I pull the throttle. I dont have any problem with the idle.

I just became my second modified flywheel.
nice, how did you do that? what does your first look like?
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Old 04-01-2007, 11:55 AM   #53
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Quote:
Originally Posted by rmdhawaii
To me, what happens on the track adds to many other variables that I cannot account for - clutch, gearing, drive train, traction, setup, engine, etc.
That's part of why I said the dyno is meaningless for this test.

Also.... all the dyno does is do a straight pull from idle to 40K+ rpm...... there are no turns on a dyno. It's like a drag race down the straightaway. You're on the straight for what..... 2- 3 seconds on a 15- 20 second lap?? You'll see a quicker peak in the HP/torque curves and thats about all you can say from the Dyno results. Will it mean anything on a particular track on any given day? No

Again... spend some more time at the track testing for yourself instead of posting your postulated theories here. That's what the rest of us are doing. The lighter flywheel will benefit you hands down... if you can tune the rest of the car to handle it
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Old 04-01-2007, 12:30 PM   #54
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Ha, take a look at the xxx main setup guide book. All of its info is pulled from real race car physics books.

So yeah. Im not going to comment back and forth anymore on the issue. Ive already laid down all the info on it.

From there we can only hope to just have mxwrench come in and give a dyno test to just see what might happen on an rc motor since its supposedly so different people seem to think it doesnt obey standard physics. Otherwise cdelong is right , to the track it goes and if you notice a difference or not is up to you.

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Old 04-01-2007, 12:42 PM   #55
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Quote:
Originally Posted by randay
nice, how did you do that? what does your first look like?
A friend of me made that with a turning lathe (right word?!?)

As I said before, bette accelaration and high speed. The engine response quicker and better.
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Old 04-01-2007, 12:44 PM   #56
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Nothing numbers wise (except within the margin of error) will change on the dyno except a shift of the curves. Where it will show is IN the car.

As pointed out before, the engine will have to do less work with lighter rotating masses and accelerate quicker.... more power at the wheels.

Why do most bracket drag racers use a 2 speed GM Powerglide?? It only consumes 18 HP because it is lighter, cheap and more efficient than other transmisions. A Ford tranny in comparison consumes 60 HP!! These numbers can be found online although they are burned in my head from years of drag racing. Same thing with rearends..... the Ford 9" is very popular because of it's effeciency and strength when compared to other brands.
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Old 04-01-2007, 01:15 PM   #57
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Alot of folks here want to discount comparing motocross motors to our RC motors when in fact they compare closer than any of the F1 or drag racing motors mentioned. Anyone who is old enough to remember or have ridden the Suzuki TM-400 dirt bike will from seat of the pants understand flywheel effect in regards to single cylinder two stroke engines. The TM-400 to this day rates as one of the most ill conceived powerbands of any two stoke dirt bike ever built. The engine made about 3 HP until the revs hit around 4 grand and then it had a about 40 -50 HP hit. This bike was the ultimate ground sky machine. It also hurt and maimed alot of dirt racers who could never manage its light switch power band in motocross type situations. The engine had a porkchop type crank fly weight and no flywheel on the magneto end of the crankshaft. Several after market companies made bolt on flywheels for the magneto end (2lbs and 4lbs I believe). These flywheels turned the TM400 from an unridable beast into something alot more manageable. The TM400 differs in one big way from our RC cars.....It was trying to put 45 HP to the ground with one tire with a contact patch the size of your hand. Our RC cars....due to 4 tires , 4WD, in a relative sence probably have the same effective contact patch but are only applying 3HP on a good day. Because of these factors, we can play the light flywheel game, zing the motor to the fat part of the HP curve, and not suffer too much from breaking the tires loose. Of course I still contend that there are certain tracks out there that the stock "heavy" flywheel can pay off.
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Old 04-01-2007, 09:56 PM   #58
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Quote:
Originally Posted by cdelong
... instead of posting your postulated theories here.
I'm just trying to get to the ground truth. If I have to postulate something and have people correct it, take pot shots at what I post or at me, that's fine. Whatever. I'm just trying learn something and hope that others can learn something as well. If I'm wrong, then I'm wrong - and I hope someone corrects me. I really don't want to publish inaccurate information.
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Old 04-02-2007, 01:52 AM   #59
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Quote:
Originally Posted by maskedrider
so which is better ??? so confuss .....

Thats easy, test different ones on your track and see which produces the better lap times. This obviously is based on you being able to run consistent times. If you cant then it wont matter which is better as you wont really notice too much.
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Old 04-02-2007, 05:21 AM   #60
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heres something you could try at home.
get a piece of string and tie a weight to it. say about 100 grams.
then spin it around horizontally so gravity won't affect it.
you should notice that it is really easy to get up to speed and you can go spin it faster using less force.

now tie a heavier weight (about 500 grams) onto the string.make sure the length of the string is the same. now try and spin that at the same frequency as before. you should notice that it is harder to get up to speed.

now while it is at speed, imagine if a drivetrain was attached to the rotating force. with all that momentum behind the drivetrain, of course there will be more force pushing the drivetrain correct?
this also means that it will take more force to slow the car down.
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