question on Comparing Spektrum 3300-3900KV motors

[64Corvette]

Three of my cars use Spektrum 3300KV-3900KV motors, each with appropriately sized ESC with either 2S or 3S batteries.

They seem to perform differently even when running the same 2S batteries. Read the specs, but other than max amperage don't really understand what it is that makes them different? No doubt I will look at this question in 12 months and realize it was a "dumb" question but putting it out there anyway.

1) Firma 3900KV SPMXSM3300
2) Firma 3300KV SPMXSM3800
3) Firma 3300KV SPMXSM1300

 

[DavidB1126]

The 2 3300kv motors should preform the same on 2s/3s id imagine since they're both the same kv, although every motor can be different. But comparing the 3300kv to the 3900kv. The 3900kv will be faster speed and torque wise. Higher kv = higher rpm. More rpm = more top speed. Theoretically, people say lower kv will produce more torque, but from what I experienced, higher kv has more initial/low end torque because of the initial rpm, as they spin up faster and the more higher amp draw.

3300kv on 2s: 27,720 max RPM
3900kv on 2s: 32,760 max RPM
3300kv on 3s: 41,580 max RPM
3900kv on 3s: 49.140 max RPM
(voltage based off of a fully charged battery)

Edit: I just realized one of the 3300kv motors P/N's are different. Could be because one motor is a different can size than the other. Which can affect performance. Mostly how hot they get, cooling, and rotor size/internals.

 

[332_RC]

1) Firma 3900KV SPMXSM3300
2) Firma 3300KV SPMXSM3800
3) Firma 3300KV SPMXSM1300

I Googled that & that's not a 3300kv. That's a 2200kv sensored motor w/ a 5mm shaft. Check the p/n please. That it's typed in correctly.

 

[CertifiedMike]

2 identical motors in 2 identical cars will perform differently with different gear ratios too.

 

[332_RC]

Unless they are different poles &/or slots, correct?

 

[332_RC]

2 identical motors in 2 identical cars will perform differently with different gear ratios too.

Yeah & that too. I missed that. And if it's two identical cars, then one motor may be damaged or a spur, etc....

 

[64Corvette]

I Googled that & that's not a 3300kv. That's a 2200kv sensored motor w/ a 5mm shaft. Check the p/n please. That it's typed in correctly.

Apologies you are correct it is Firma 3300Kv SPMXSM4800 not 3800