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Old 10-09-2010, 03:53 PM   #1
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Default Need clarification, on some things!

Someone please explain...
There are classes, I know...truck, Nitro, Touring Car...etc. Now...with the brushless motors..we have 25.5..21.5..17.5..13.5....etc. We also have something called "kv ratings." In 13.5 alone, I've seen a spread of fron...2200-3300 kv. That's when they are listed as 13.5 turn. How can that be?
Where can we see a listing of "kv ratings" for the different classes???
Thanks!
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Old 10-09-2010, 06:23 PM   #2
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All motors vary a little from company to company but here it is from Novak...
21.5=1800kv
17.5=2200kv
13.5=3300kv
10.5=4200kv
8.5=5000kv
7.5=5800kv
6.5=6400kv
5.5=7400kv
4.5=9000kv
3.5=10500kv
The lower the turn or the higher the kv... the faster the motor

The higher the turn or the lower the kv... the more torque

Think of it as s.a.e. versus metric

As long as someone is not running a faster motor than the highest 13.5[or 17.5 or 21.5 whatever the class] no one should be complaining...
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Old 10-13-2010, 08:33 PM   #3
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ok.... maybe...try to think of it this way...... "horsepower" is a mathematical equations between torque and rpm.....some companies motors make the power differently so they are a different kv but they end up with the same end power......the important part is that it is "spec" for the class...and with brushless it usually comes down to the speedcontrol and how much boost and timing you can shove down the throat of the motor. an example is how in touring stock you can pimp out a 17.5 on a tekin rs and make it pace a 13.5 unboosted.

this is kinda the same with brushed motors where you can have two 12turn motors but one is called a 12 double and the other a 12 single.....they will end the same but the curves and torque outputs are different.
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Old 10-13-2010, 09:50 PM   #4
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For racing most places use a turn rating because it sets a standard they can control. Way too hard to specify a Kv rating and check it. If they specify a 13.5 it's easy to check, fast or slow if it's a 13.5 it's legal. If rules were set by Kv there would no real way to check and you would have manufacturers building motors that they say are 4200Kv for example and really they'll turn 5000Kv making them faster, boosting sales but I'm sure none would do that
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Old 11-04-2010, 06:57 AM   #5
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Probably similar to full scale... engine displacement = turns while horsepower = kv.

Engine size limited to race rules, but amount of power a manufacturer can squeeze out of that design is up to them.
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