RC10Talk - The Net's Largest Vintage R/C Community

Can someone explains the correlation between turn and kv. And how it relates to the track and raceing..

Kv rating means for every (V) or volt of input current to the motor, you get (RPM) out- so a 3300KV with a 7.4v 2sLipo gets a max 24,420 theoretical RPM. Turns are just like brushed motors, it relates to the amount of wire wrapped around the stator (instead of armature), the fewer turns, the more RPM (and torque) the larger the number, the higher the resistance and the fewer RPM's-

Most sensorless motors are KV rated, most sensored motors are in turns-

A 3100-3300KV is about a 13.5-

Good into and thanx for the quick response .. so a stock class running 17.5 turn motors are what kv? Is there a Formula? If I run a 5700kv. what turn does this equal .

5,700 X 7.4v (avg) = 37,800 RPM, that's near a 7.5-

slvrback wrote: If I run a 5700kv. what turn does this equal .

There is no direct conversion between kV and turns though, a 5700kV could be anything between 6.5T and 8.5T, depending on the motor design. Rotor magnet strength, rotor diameter, air gap, wire diameter in the windings, type of windings will all affect the kV of a motor.
Race motors use turns because it should be pretty simple to measure wire diameter and how many turns of wire are used in the motor. kV ratings work for the basher crowd as their biggest concern seems to be "how fast does it go, mister?"

The Novak motor spec chart will give you an idea of rough equivalents http://www.teamnovak.com/products/brushless/motor_spec_chart.htm

and on e you factor in timing, and even better, variable timing, it gets even more intricate

then again we re a vintage site

Is a BL motor labeled "R" different than a "T"? Like 17.5R versus 17.5T

tommy2c wrote:Is a BL motor labeled "R" different than a "T"? Like 17.5R versus 17.5T

Some of the branding like Speedpassion? were calling them R- but it was just a name-