motor size vs. kv.

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, and others.

N.Mango

🤪I swear the voices are real!🤪
Premium Member
Hospitality Award
Build Thread Contributor
Messages
6,128
Reaction score
15,238
Location
Kapaa, Kauai, Hawaii
Arrma RC's
  1. Kraton EXB
  2. Typhon 6s
Can the size of a motor make up for a high kv? Meaning would a big motor do ok with a high kv compared to a smaller motor with the same kv which would have heat issues etc.?
 
The motor can itself is a heatsink; a larger motor has surface more area to dissipate heath. So yes, the larger motor should run cooler all other things being equal.
But is it ok to do so? Like running gearing that would be a "no no" for a smaller motor with the same kv.
 
But is it ok to do so? Like running gearing that would be a "no no" for a smaller motor with the same kv.
To a certain extend and that’s the tricky part😉. I for example had a 4074 2000kv motor and replaced it with a 4082 2000kv motor. The 4082 should run cooler and although I don’t have the data I think it does.
Edit: I don’t think the 4082 can handle way higher gearing than the 4074. Maybe 1 or 2 additional pinion teeth. For more you’d better go with a more powerful motor (more Watt), usually lower kv.
 
To a certain extend and that’s the tricky part😉. I for example had a 4074 2000kv motor and replaced it with a 4082 2000kv motor. The 4082 should run cooler and although I don’t have the data I think it does.
Yea tricky for sure.
Thanks for your help.
I was asking because one of my RC's I put in an oversized motor to push way too high gearing.
It seems to have no issues but would hate to later find out that I fried something because I shouldn't have done that. :ROFLMAO:
 
Remember the bigger motor will make more torque, so it won't be working as hard to turn similar gearing. But, total power is still total power, so the amps won't go down.

What motor and KV are we talking here? Old size/new size?
 
I think you have to take the fully loaded vehicle weight onboard when considering a motor for your vehicle as a motor that is too small simply will not generate the torque necessary to get your car to get up and go, completely irrespective of KV. Conversely there is a point where a motor and the necessary ESC becomes too large for the platform making all the available power pointless. When comparing motors, if you'll forgive the simplification, you can use the weight of the motor as a point of reference for how much power (KW) it can generate. It's not exact but two motors, all other things being equal, the heavier motor will have more power. Once you've made that choice your KV rating should play off of how many volt you intend to put in the system taking the motor's max RPM into account. That's my $0.02 anyways.
 
Remember the bigger motor will make more torque, so it won't be working as hard to turn similar gearing. But, total power is still total power, so the amps won't go down.

What motor and KV are we talking here? Old size/new size?
Basically I have a a bigger pinion...high output trans...high output ring and pinion diffs. (Axial SMT10)
I don't know ratio's off hand but I have a MMX /1515 2200KV CC Combo.
I have ran this with a smaller motor with no real issues but haven't ran it for very long before
upping it to the 1515. I'm assuming the 1515 should be ok to run if the smaller motor was doing ok....???
I think you have to take the fully loaded vehicle weight onboard when considering a motor for your vehicle as a motor that is too small simply will not generate the torque necessary to get your car to get up and go, completely irrespective of KV. Conversely there is a point where a motor and the necessary ESC becomes too large for the platform making all the available power pointless. When comparing motors, if you'll forgive the simplification, you can use the weight of the motor as a point of reference for how much power (KW) it can generate. It's not exact but two motors, all other things being equal, the heavier motor will have more power. Once you've made that choice your KV rating should play off of how many volt you intend to put in the system taking the motor's max RPM into account. That's my $0.02 anyways.
I do believe I'm over powered to the point of having useless power but hopefully not too much of a loss as all my gearing is pretty high and it needs a lot of power to push it. :unsure:🤷‍♂️
 
I think you have to take the fully loaded vehicle weight onboard when considering a motor for your vehicle as a motor that is too small simply will not generate the torque necessary to get your car to get up and go, completely irrespective of KV. Conversely there is a point where a motor and the necessary ESC becomes too large for the platform making all the available power pointless. When comparing motors, if you'll forgive the simplification, you can use the weight of the motor as a point of reference for how much power (KW) it can generate. It's not exact but two motors, all other things being equal, the heavier motor will have more power. Once you've made that choice your KV rating should play off of how many volt you intend to put in the system taking the motor's max RPM into account. That's my $0.02 anyways.
+1
 
  • Larger motors add more weight
  • Larger motors require more power
  • Higher KV motors pull more amps / generate more heat
  • Larger motors produce more torque
  • Larger motors have a larger cooling surface.

You sort of have to take those pieces and see what works for you.
 
  • Larger motors add more weight
  • Larger motors require more power
  • Higher KV motors pull more amps / generate more heat
  • Larger motors produce more torque
  • Larger motors have a larger cooling surface.

You sort of have to take those pieces and see what works for you.
Since I'm using what I already have I guess its trial and error. :oops::p
 
Since I'm using what I already have I guess its trial and error. :oops::p
Unless someone has done it before and has some very good data to share.... most of this hobby is trial and error(y)
 
Unless someone has done it before and has some very good data to share.... most of this hobby is trial and error(y)
I just ran the Jconcept Renegades (biggest tires I ran so far) in tall grass and motor stayed cool to the touch.
Not enough runs to make a solid conclusion but it's a great start😅🤞
 
Old Thread: Hello . There have been no replies in this thread for 90 days.
Content in this thread may no longer be relevant.
Perhaps it would be better to start a new thread instead.
Back
Top