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Old 06-10-2011, 11:43 AM   #1
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Default Brushed vs Brushless

Can anyone tell me the "real world" equivalents from brushed to brushless? I say real world because, for instance, I had a 15t brushed motor, and mathematically converting it to brushless put it around 42-4500kv. Well I put a 3500kv brushless motor in that car with the same gearing and it not only pulled harder but was faster. So that conversion isn't quite right considering 4200+kv would be faster than 3500kv. My reasoning for this is I used to have a Losi XXXs that had a 4t brushed motor in it and I want to know what brushless motor would be equivalent in speed.

Thanks for any help. If you need any clarification please let me know. I explained it the best I could think of.
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Old 06-10-2011, 02:22 PM   #2
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there is no exact formula i beleive. initially the thought process was you would double the wind from brushless to brushed, ie a 13.5t brushless would be a 27t brushed. however, brushless motors and esc technology is so much more effecient that this now isnt the case. an old 10t brushed is probably now slower than a 13.5t turbo'd brushless.

if you get a decent esc, you can now pretty much get the motors to rev as much as you like due to the variable timing that they offer. you can get a motor that revs at 2700kv to around 15000kv with the variable timing on offer!

amazing stuff really!
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Old 06-10-2011, 02:33 PM   #3
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It's not just about revolutions per volt or rpm, you got to consider efficiency as well. Brushless design are naturally more efficient than their brush counterpart. Also you will have to consider that the motor reach their maximum efficiency at full rpm and heat is their enemy. As heat increases, efficiency decreases. Therefore, a good design motor is a motor that does not get as hot or get hot at all when under load, and are able to hold its rated rpm well, good torque. this kind of motor has the best efficiency. Also when efficiency fall off because of heat increases, the motor will draw more current from the battery to maintain it's rated rpm and torque. This result in shorter run time and heat built up on the battery and esc.

Hope that helps.
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Old 06-10-2011, 02:44 PM   #4
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17.5=27T
13.5=19T
9.5=17T
8.5=15T
7.5=12T
6.5=10T
5.5=9T
4.5=7T
3.5=5T
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Old 06-10-2011, 03:20 PM   #5
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Quote:
Originally Posted by Foxxrocket View Post
17.5=27T
13.5=19T
9.5=17T
8.5=15T
7.5=12T
6.5=10T
5.5=9T
4.5=7T
3.5=5T
this may be the "equivilent" in theory, but in practice it is nowhere near. a 13.5 brushless is easily as "fast" as a 12t brushed these days.
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Old 06-10-2011, 04:37 PM   #6
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Quote:
Originally Posted by jrowles91 View Post
My reasoning for this is I used to have a Losi XXXs that had a 4t brushed motor in it and I want to know what brushless motor would be equivalent in speed.

Are you sure that you had a 4 turn brushed motor in your Losi car. I guess they existed but a 6 turn motor was about the fastest that anyone made, and they turned so many RPM's they had to have special things done to them to keep them working somewhat properly.

I would look at that motor again.


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Old 06-10-2011, 04:51 PM   #7
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whats brushed ?
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Old 06-10-2011, 05:36 PM   #8
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when talking logical speeds

i honestly prefer brushed

with all the new technology and escs, ive had more problems with brushless stuff in a couple months, than i have had with brushed stuff in 10 years

i have a 14x2 trinity speed gems in my old xl1 rustler, its running vintage electronics(novak cyclone)

and i can outrun a vxl rustler(same gearing, same battery)

yea my motor runs that 5 degrees hotter, and i gotta switch brushes like what.. once a year?


for speed runs, brushless is fine, because you can go much faster with brushless than brushed

but for 10th scale and under, racing, bashing(with realistic speeds, not 60mph... thats not realistic, its just plain stupid)

i will stay brushed

for 8th scale, i have no choice to go brushless, 4s lipo +brushed= lots of brushes lol
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Old 06-10-2011, 09:37 PM   #9
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Mod Brushed motors (6t/7t) can compete in small tracks, and 27t stock motors do well against 17.5 blinky. I think if you have invested alot in brushed motors you should have a dedicated brushed car, in addition to your brushless kit. As far as 4t brushed motors, I think the fantom alloy2 is the only one available, and its extremely powerful !!! I would say it is as powerful as a 2.5t brushless, but with less rpm ...
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Old 03-03-2014, 02:22 PM   #10
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hi im looking at fitting a brush less 16t in my tamiya tl01 do i need to change my esc if i want to run lipo batteries thanks
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Old 03-03-2014, 03:10 PM   #11
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Quote:
Originally Posted by Mb3195 View Post
this may be the "equivilent" in theory, but in practice it is nowhere near. a 13.5 brushless is easily as "fast" as a 12t brushed these days.
Exactly. A Justtock ESC and Turnigy 13.5 will be as fast or faster and last more then a single run for about $100.
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Old 03-03-2014, 06:00 PM   #12
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Quote:
Originally Posted by Mb3195 View Post
this may be the "equivilent" in theory, but in practice it is nowhere near. a 13.5 brushless is easily as "fast" as a 12t brushed these days.
17.5 is much faster than any 27T. 13.5 at the Tamiya track are putting faster lap times down than Reedy invite drivers were when 10t motors was the limit
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Old 03-03-2014, 06:33 PM   #13
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At this point, I can also say that brushed motors are being outperformed because they are not allowed to use the same materials as the brushless motors, and they are not allowed to run the same number of turns. If you put Neo magnets in a 27T brushed motor or a 17T brushed motor, it will smoke any 17.5t brushless motor period !!! Forget about putting Neos in mod brushed motors !...lol... Imagine if you could crank up the brushed motor timing on top of it all... It would be a wrap for brushless motors.....

Last edited by bertrandsv87; 03-03-2014 at 06:47 PM.
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Old 03-03-2014, 06:55 PM   #14
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Quote:
Originally Posted by bertrandsv87 View Post
At this point, I can also say that brushed motors are being outperformed because they are not allowed to use the same materials as the brushless motors, and they are not allowed to run the same number of turns. If you put Neo magnets in a 27T brushed motor or a 17T brushed motor, it will smoke any 17.5t brushless motor period !!! Forget about putting Neos in mod brushed motors !...lol... Imagine if you could crank up the brushed motor timing on top of it all... It would be a wrap for brushless motors.....
I'll keep my brushless motors, thank you very much... A few things I don't miss include cutting commutators and swapping brushes every few runs. If we were still running brushed motors, I'd have taken up a different hobby a long time ago.
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Old 03-03-2014, 07:06 PM   #15
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Understood, but in a fair comparison, brushed wins hands down... I still have a decent stock of brushed motors, and maybe I'll have some Neo magnets installed in one of my motor cans just to put my theory to the test...lol....
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