TimK

hello,
I have a Slash 4x4. I am 61 years young with my first RC. I'm off work recuperating from a work injury, and my new hobby has been a great source keeping me away from boredom these past weeks.
My question is...why do some go to 2200kv motors, while others choose 4200kv and higher? I figure with the lower kv, you have to gear up more to get the same high speed, whereas with a higher kv to begin with, you can keep the same gear ratio and have a high speed too.
I understand motor temp is always a concern, so is the lower speed motors(and larger in size) a better way to go?
Your thoughts appreciated.

Dave H

Different battery voltages. The ~4200 kv motors are with a 2S lipo for ROAR rules. The ~2200kv motors are used with higher voltage, 3S and 4S most likely.

The higher voltage setup done right is more efficient, probably either running at tracks that don't enforce ROAR rules or aren't racing them.

mydudrevo

iTrader: (1)

They are using different sized motors. When they say 2200 its likely that its a castle 1/8 2200 and when they say anything from 3500-5200kv it's a 540-550 short course motor I recommend going with a sc designed motor like the tekin 4300 pro4hd it's a power house more power than you can actually effectively use

ta_man

iTrader: (168)

If this is your first car, I would NOT recommend a Tekin Pro4HD 4300!

Unless you have an RX-8, Mamba Max Pro, or something similar it will overload your ESC and it is very hard on batteries, easily drawing so much current that it can damage low C-rated batteries.

mydudrevo

iTrader: (1)

Yes he will need a good esc but the draw isn't bad in a light truck like a slash so 5000mah 30c should be fine IMO

meno1103

iTrader: (6)

There's several factors, along with the kv, that can alter the tendencies for the motor to generate heat (which is one reason people run lower kv motors). A higher kv means less torque, which means more stress on the motor to move the vehicle, and to alleviate the stress, higher gear reduction is used (smaller pinion) which in turn negates some of the higher speed from the higher kv motor. There's also a limit to how much gear reduction can be used because if you go past a certain point, the motor is taken too far out of its efficiency range and will generate heat from that. Basically, you want torque for a 4x4 short course truck, not just rpms. A 540 size 4 pole motor at 4000kv would be a good step up from the stock velineon motor with 2s when racing or just playing around, or 3s when just playing around.

Some notes, I found the velineon plenty powerful on 3s and fun for 'bashing'. I did try running a 4300kv 540 2 pole and it did not do well on 3s, generated too much heat to run a full pack although it was noticeably quicker on 2s with ok temps. The same truck now has a 1/8 castle 2650kv and it is great all around except it is a bit heavier than before but the motor can virtually take any gearing, always runs cool, and I've run into no issues when switching between 2s, 3s, or the rare 4s pack without altering the setup. It's been clocked at 74mph with a 4s while still being set up for the track, tires and all.

RiceP

iTrader: (71)

Ok if this is your first truck you probably are not a pro yet and don't need to spend that much I see pro4 hd's used go for $135 so if you don't want to break the bank on a motor I suggest u go with a tenshock 411 4600kv or 4000kv they go for around $70 used and are smooth and efficient they do like current like the tekin and even with the light slash I would not go below 60c lipos with any sc truck. There is nothing wrong with the tekin I do run them but they are costly. So make your own choose but IMO stay between 4000kv and 4800kv in which ever brand motor u choose running on 2s.