# What does the KV stand for on motor



## smoothie (Mar 23, 2004)

I am looking at a couple brushless motors and want to know what the 
KV stands for. I race on a carpet oval track. Whats the difference between 6800KV and 8000KV? Is there a rule of thumb for motors? Thanks.


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## martian 710 (Jan 22, 2004)

Kv stands for the rpms the motor will turn per volt of current with no load.


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## smoothie (Mar 23, 2004)

So which is better for shorter tracks?


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## TamiyaKing (Nov 14, 2008)

The term is kilavolt


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## ta_man (Apr 10, 2005)

martian 710 said:


> Kv stands for the rpms the motor will turn per volt of current with no load.


Note that "RPMs the motor turns" is not a direct indicator of power output. The big motors used in electric 1/8th scales have very low Kv ratings but lots of power because they produce so much torque. Also, it is not a "volt of current" since current is measured in Amps, not Volts. It is just "RPM per Volt".



TamiyaKing said:


> The term is kilavolt


"KV" (all caps) is Kil*o*Volt, not Kil*a*volt
"Kv" (Cap and lower case) as applied to brushless motors if the "Voltage Constant" - RPM per volt.


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## nutz4rc (Oct 14, 2003)

What type of vehicle and what type of track are you asking about. There is a big difference between a short oval and a short on road, dirt vs carpet, etc. More detail will help in getting an answer.


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## smoothie (Mar 23, 2004)

I plan on running these in my losi mini slider and losi mini late model on a small flat carpet oval


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## daver (Dec 12, 2001)

Where are you planning to run it? Just as an FYI, some tracks (Summit) will only allow 4200Kv.


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## smoothie (Mar 23, 2004)

Mostly in Van Wert but possibly in Fort Wayne and/or Columbus


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## TamiyaKing (Nov 14, 2008)

ta_man said:


> Note that "RPMs the motor turns" is not a direct indicator of power output. The big motors used in electric 1/8th scales have very low Kv ratings but lots of power because they produce so much torque. Also, it is not a "volt of current" since current is measured in Amps, not Volts. It is just "RPM per Volt".
> 
> 
> "KV" (all caps) is Kil*o*Volt, not Kil*a*volt
> "Kv" (Cap and lower case) as applied to brushless motors if the "Voltage Constant" - RPM per volt.


Ahh i was going for the O and not the A opps.


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## smoothie (Mar 23, 2004)

so does the lower the number mean faster or slower than a higher number?

6800Kv
8000Kv

How would I gear these motors on a losi mini slider and/or late model?


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## CustomWire (Jan 12, 2009)

1000 rpms per volt most times on a brushless

so the 6800 times say 8 volts is 54,400 rpms on bench
and the 8000 times 8 volts is 56,000 rpms on bench real world the leath of the front or back str8 will give u better idea how do u find that out i dont know..

Higher Kv is higher RPMS per volt 
so Kv times Volts = RPMS < bench 15% off maybe for real world ..


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## pup1970 (Apr 2, 2008)

In most cases, the lower kv ratings will have more torque due to being able to use a larger diameter wire in the windings allowing more amperage through the wire.


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## ta_man (Apr 10, 2005)

pup1970 said:


> In most cases, the lower kv ratings will have more torque due to being able to use a larger diameter wire in the windings allowing more amperage through the wire.


Where do people get this stuff? That is exactly backwards: Lower Kv is because the motor has more turns that generate the back EMF. To get more turns in the same space you need smaller wire not bigger. Look at any motor spec chart that lists the number of turns and Kv and you will see the higher turn motors have the lower Kv.

It is not necessaryly true that lower Kv produces more torque. Patrick DelCastillo (President of Castle Creations) mentioned (on RC-Monster) that the 7700KV motor can produce as much torque as the Lower KV motors, but it would take 700 amps to do it.


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## dano628 (Dec 13, 2006)

Its a matter of choice I run a mamba 8000 in my mini . On the same track ta man uses a mamba 6800 both geared differently both are very fast .


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