'19t' motor comparisons

[Garry]

Similar to the 13.5 thread here (http://www.rcracechat.com/vb/showthread.php?t=35377), but as no-one seems to have a '19t' guideline, the motors listed are general ones considered as '19t equivilent'.

Novak EX10.5 SPORT (#3431)
195W
4200kv
bonded rotor

Novak SS4300 (#3401)
195W
4200kv
bonded rotor

Novak SS10.5 PRO (#3410)
235W
4200kv
sintered rotor

Nosram Dragon Brushless Sports Modified 10.5T (#90520)
180W
4100kv
bonded rotor

LRP Eraser 10.5turn (#LRP50360)
180W
4100kv
bonded rotor

Speed Passion 9.5 (#SP34809)
225W
4400kv
*bonded rotor

------------------------------------
* denotes that its unknown which rotor is is included at the moment
------------------------------------

Can't remember any other '19t' brushless motors. :p

[tim.walden]

Scrutineering of Brushless Motors is not an area we have much experience of yet.

Kv is the revs per volt of the motor but this affected by timing and by rotor.
Rotor material - almost impossible to check
Rotor diameter - required detailed knowledge of what each motor should be.
Turns - Speed Passion 9.5t motor does in fact have 9.5 turns. Do all the other motors have turns that are same as label? Does anybody know this please?
Resistance - Because there are no brushed we can accurately measure resistance of the windings. For a given number of turns if you can get less resistance by getting more wire diameter into the motor it will pull more amps. I think we need a minimum resistance figure for 9.5t and for 13.5t to limit specials and development of stock motors. For a simple method to measure this put a 0.1 ohm 1% resistor in series with one pair of motor tabs, connect a single 1.2 volt cell across the motor+resistor, then with a Digital Volt Meter (DVM), measure the voltage (Vr) across the 0.1 ohm resistor and the voltage (Vm) across the two motor tabs, then the resistance of the motor = (Vm/Vr) x 0.1 ohms. Accuracy is within a few percent.

If you can do this please have a go and post some results as this may the easy way to check and compare motors. I have done a quick test on the range of Speed Passion motors and each wind gives a significantly different result to the next wind up or down. What I do not know is how these compare to other manufacturers motors.