Motor help with Kv

[michael_fly_more]

Hi all

im after building a new Jr. Forza speed
and not sure on motor choice and what's best when it comes to kv

the manual says 500-560kv

with Kontronik I have 2 choices either 750-50 or 750-56

if I went 800 size the only choice I have is 800-48 or 800-60 so no good really

question is I know going one way or the other I can change the pinion to get the head speed within the ideal % for the kosmik esc

but is there any difference between a 500kv or 560kv motor?? And is one better to use than the other
and am I better to have the 500kv with larger pinion or 560kv with smaller pinion?

other choice I have is normal pyro or competition?

I understand the gearing esc % and higher Kv the faster the motor runs but is there more to the Kv motor

really hope some one can help me on this

thanks all

M

[tomatwalden]

..

but is there any difference between a 700kv or 760kv motor?? And is one better to use than the other
and am I better to have the 700kv with larger pinion or 760 with smaller pinion?

other choice I have is normal pyro or competition?

I understand the gearing esc % and higher Kv the faster the motor runs but is there more to the Kv motor

really hope some one can help me on this

thanks all

M

I assume you mean 500kv or 560kv? According to the Kontronik website, both the 500kv and 560kv versions of the standard Pyro have the same power output (4.5kW). The competition version has a higher (5kW) power output.

As you say, otherwise the Kv just gives you the RPM (in 1000s) per volt.

[Grumpy]

Theoretically the higher Kv running a lower gearing could be a little more efficient. Reason being that the high Kv motor running lower gearing makes less torque and less torque means that the Iron losses in the motors core are lower.

[Granpappy]

Lower Kv motors have more grunt, but it's easier to strip the main gear with a high tooth pinion.

[Si Goodchild]

Lower Kv motors have more grunt, but it's easier to strip the main gear with a high tooth pinion.

Really? My experience is that small pinions strip main gears more readily than large, high tooth count ones.

[Grumpy]

Really? My experience is that small pinions strip main gears more readily than large, high tooth count ones.

That's certainly 'conventional wisdom'.. the small pinion being smaller in radius puts less teeth in mesh with the main gear and so more prone to stripping.

[hellraiser]

We have a couple in our club including mine, 13 tooth pinion & Align Dominator RCM-BL850MX (540KV), goes like stink............

[Granpappy]

Really? My experience is that small pinions strip main gears more readily than large, high tooth count ones.

What I meant to say was low Kv motors have more grunt and therefore it's easier to strip the main gear with a high tooth pinion then a high Kv motor with a low tooth pinion. It probably wont make a difference if you are only looking at the difference between a 500kv on 13T and 560kv on 12T. But a 370kv on 15T will apply a lot more torque on the main gear. Really!