Go Back  R/C Tech Forums > General Forums > Monster Trucks
Motors, motors, motors - turns and RPMs >

Motors, motors, motors - turns and RPMs

Motors, motors, motors - turns and RPMs

Old 03-15-2024, 07:49 PM
  #1  
Tech Rookie
Thread Starter
 
Join Date: Feb 2021
Posts: 3
Questions?? Motors, motors, motors - turns and RPMs

Old RC vet here but newb to all the new motors and terminology. Can someone explain how turns and RPMs have changed with brushed motors? I used to think that the lower the turns the faster and more RPM the motor would run at usually meaning higher speed. The larger the can - the higher the torque. I'm used to vintage trucks - so when I wanted something faster, I would switch from say a LeMans O5 to a Mega 360 (22T and 21K RPM) or a Trinity Speed Gem Monster Mash that was 16T 40K RPMs. Do current brushed motors still work the same way? What am I missing?

I put a Hobbywing QUICRUN Brushed 555 (really because I got a good deal on the combo with an ESC) which is a 13T and although Hobbywing states on their site this motor is good for monster trucks it only was making 14K RPM and was pretty slow in my old school Big Brute. I was thinking because it was a 13T - I would blow the gearset in a second but it wasn't fast at all. So, it can't be just the can size making that much of a difference. Trying to do some research and I came across 3 slot vs 5 slot - which may be another reason but to be honest - now I'm totally confused. Seems like the old rules aren't really valid anymore...LOL.

For example Hobbywing has 2 QUICRUN motors - a 540 30T can making 14K RPM and my 555 can 13T making 14K RPM - so what's the difference in these motors from an application standpoint? And how would these motors compare to the Holmes Hobbies 15T Retro Sport for instance? I need some of you young whips to tell me how it is now!
nick1ster is offline  
Old 03-26-2024, 11:47 AM
  #2  
Tech Adept
iTrader: (9)
 
Join Date: Feb 2010
Location: California
Posts: 136
Trader Rating: 9 (100%+)
Default

I don't think there's really that much difference between brushed motors now and then overall, but one major difference is the majority of brushed motors are for crawlers now.

The more slots the more torque and smoothness at expense of speed. Most 550 basher motors these days are 3-slot (Reedy/Traxxas/etc) whereas crawlers are 5-slot.

or example Hobbywing has 2 QUICRUN motors - a 540 30T can making 14K RPM and my 555 can 13T making 14K RPM - so what's the difference in these motors from an application standpoint?
both of those are crawler motors really, just for different size/weight crawlers. But they would also be useful in vintage vehicles or scalers. They run at the same speed because the 3-slot but higher turns and 5-slot with lower turns kinda cancels out, but the 555 will have more torque due to the larger can.

​​​​​​​And how would these motors compare to the Holmes Hobbies 15T Retro Sport for instance?
The Holmes 15T Retro sport is a traditional brushed mod racing motor, 3 slot, This Holmes page is incredibly useful: https://holmeshobbies.com/motor-recommendations and even charts motors they don't make.

As you can see they claim the 15T Retro Sport is 2900kV. On a 2S battery at full charge (8.4v), that's 8.4v * 2900kV. = 24360rpm.
jauntyfedora is offline  
Old 03-26-2024, 12:37 PM
  #3  
Tech Addict
 
1995 Monster T's Avatar
 
Join Date: Apr 2021
Posts: 585
Default

I have found the lower the turn and more RPM the faster you will go. Single turns are great for monster trucks. I have tried many 540 brushed motors in monster trucks and found that they just don't compare to 550 size motors. Especially in Kyosho trucks. Use a 550 sized motor. The 540 motor just don't have enough torque for the gearing in kyosho monster trucks.
1995 Monster T is offline  
Old 04-05-2024, 07:10 AM
  #4  
Tech Rookie
Thread Starter
 
Join Date: Feb 2021
Posts: 3
Default

Originally Posted by 1995 Monster T
Single turns are great for monster trucks.
So, is the real reason for the difference the # of winds? The old school Trinity Speed Gem Monster Mash was single wind 16T and 40K RPMs. Is this the major difference in why they are able to produce much more speed in a monster truck application? So the Holmes 15T Retro is - by definition, because of its lower turn count - it should be "faster" than the Speed Gem, but obviously doesn't reach that same RPM. Is the difference the winds and the Holmes is probably not a single wind? The single wind generally has more torque and punch down low to make it quicker off the throttle?
nick1ster is offline  
Old 04-05-2024, 11:13 AM
  #5  
Tech Addict
 
1995 Monster T's Avatar
 
Join Date: Apr 2021
Posts: 585
Default

The monster mash motors are not Speedgem motors. They were designed for monster trucks with big tires to turn faster at the start. The Holmes retro was designed for what type? The only Speedgems motor for trucks was the Saphire 17 single 24K RPM. Big difference from the monster mash motors.@16 single 40K RPM The winds are how fast the power is released. Single all at once double start and top end ect. Quad had 4 power bands Brushed motors just don't last and require constant brush changes and cleaning. Brushless is way better. Lots of power and no cleaning. I have found that 550 size motors work better in monster trucks.

I found this handy kv convertor RPM to solve your problem. Kv to RPM Calculator - Calculator Academy Put in voltage and kv to get RPM. Your Holms 15t motor with 2900 kv doesn't even come close to 40 k RPM. To get to 40K rpm you need a 5700 kv motor.

Last edited by 1995 Monster T; 04-06-2024 at 07:30 AM.
1995 Monster T is offline  
Old 04-08-2024, 05:38 AM
  #6  
Tech Master
iTrader: (9)
 
nrtv20's Avatar
 
Join Date: Jan 2005
Location: Northwest Ohio
Posts: 1,030
Trader Rating: 9 (100%+)
Default

As stated above, it's about the number of slots on the armature. 3 slots was the type of motor used in racing and the 5 slot as stated is for power not RPM. Just think of it as 3/5 as fast. More pole activations to make a full revolution.
nrtv20 is offline  
Old 04-08-2024, 07:55 AM
  #7  
Tech Adept
iTrader: (3)
 
Join Date: Sep 2010
Location: Upstate, SC
Posts: 106
Trader Rating: 3 (100%+)
Default

Originally Posted by nick1ster

For example Hobbywing has 2 QUICRUN motors - a 540 30T can making 14K RPM and my 555 can 13T making 14K RPM - so what's the difference in these motors from an application standpoint? And how would these motors compare to the Holmes Hobbies 15T Retro Sport for instance? I need some of you young whips to tell me how it is now!
The 555 can has more torque for monster trucks with big tires.

The easy way to go faster now is to add more volts, the new high volt lipo batteries are fantastic as long as your esc can handle it
leadfootedfool is offline  
Old 04-09-2024, 08:35 AM
  #8  
Tech Lord
 
Roelof's Avatar
 
Join Date: Aug 2007
Location: Holland
Posts: 12,500
Default

Originally Posted by nick1ster
So, is the real reason for the difference the # of winds? The old school Trinity Speed Gem Monster Mash was single wind 16T and 40K RPMs. Is this the major difference in why they are able to produce much more speed in a monster truck application? So the Holmes 15T Retro is - by definition, because of its lower turn count - it should be "faster" than the Speed Gem, but obviously doesn't reach that same RPM. Is the difference the winds and the Holmes is probably not a single wind? The single wind generally has more torque and punch down low to make it quicker off the throttle?
A 555 motor is longer. with the same windings as a 540 is has more length wire and so a higher resistance making de current lower. Current is one of the factors determining the magnetism strength and with that the speed of rotation. The torque of the 555 comes from the larger surface of the rotor and magnets due the longer case.

And then the question what timing is set. Most silvercan 540 motors have a default timing, rebuildable 540 even more. The 555 is probably also a silvercan and maybe even with a zero degree timing because these motors are well used in electric tools.
Roelof is offline  

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Your Privacy Choices -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.