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Which motor is 'technically' faster?

Which motor is 'technically' faster?

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Old 01-27-2012, 01:17 PM
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Default Which motor is 'technically' faster?

Ok... so brushed motors used to be a fairly easy thing, brushless is a bit different.

Is the speed of a motor ultimately determined by Kv rather than turns?

For instance... take these 2 Trinity motors:

Nemesis 13.5 Turn - 3,400Kv

Speedgem 12.5 turn Motor, Titanite, 3200kv

So the 13.5 turns has more turns (traditionally slower) but higher Kv (faster)... and the 12.5 has fewer turns (faster) and lower Kv (slower).

Not that you would necessarily notice a difference of 1 turn and/or 200 Kv... but in concept... Is the 13.5 turn motor above more powerful?

The numbers become MUCH more different when comparing a name brand motor to a lesser brand chinese motor. I've seen 5.5turn motors rated at 7200 Kv and a 5.5t hobbyking x-car motor that is rated 6000Kv. I assume in that scenario the higher Kv trumps the other.

But should I even bother looking at turns these days? Or does only Kv matter and the turns are just a way to acheive the Kv number?

Thanks!
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Old 01-27-2012, 02:13 PM
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Kv is only half of the story of power, it's just a RPM rating. Without knowing torque the question can't be answered (other than possibly comparing similar motors)

Power = torque times RPM (with appropriate units and radial conversions)

Power is what makes a motor fast. And determines acceleration.

Not torque or Kv/RPM by themselves. Can be used to suggest best gearing, that's about it though.

Torque can vary substantially due to a variety of factors in how the motor is built, materials, etc.
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Old 01-27-2012, 02:50 PM
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What Dave H said.

Just pay attention to kV in your case

There are things like 2 pole, 4 pole or 6 pole motors for cars.
Then there is slotted and slotless 2 pole motors.
There is rotor diameter and length to be considered.
The diameter of the motor shaft that goes through the rotor that makes a difference.
Is the rotor segmented or sintered?
Is the rotor kevlar or carbon wrapped?
Sensored vs Sensorless.
Delta or Wye winds.


There is more, but you get the point.
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Old 01-27-2012, 03:02 PM
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Brushed isn't really all that much different at least in principle. I have good quality 19T motors that are way faster than some cheap 12T motors I once bought for my little guy.

Although there are more differences today, due to increased diversity of designs and manufacturers, as Snellemin listed. Certainly understand it's confusing.
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Old 01-29-2012, 11:57 PM
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Originally Posted by Dave H View Post
Brushed isn't really all that much different at least in principle. I have good quality 19T motors that are way faster than some cheap 12T motors I once bought for my little guy.

Although there are more differences today, due to increased diversity of designs and manufacturers, as Snellemin listed. Certainly understand it's confusing.
Yes... it's very confusing for us newbs. Thanks for this thread, it answered many of my questions.
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