CMS36-5700 vs 6900
 

I have a T4 running a MM5700 combo. Normally I run the truck on 2s. Just for kicks today I wired two 2s packs in series and added a receiver pack. Since the 5700 is not rated for 4s I only ran a couple of bursts out in the yard. Needless to say, the truck really woke up, but it is definitely a little too much.

I'm wondering what kind of power/speed increase I would see going from the 5700 on 2s to the 6900 on 2s?

My other option would be to buy new batteries and run the 5700 on 3s.

I would go with the 5700 on 3s. Its better to go with the higher voltage. You will have lower amp draws and everything should stay cooler.

and it should go 100km/hr :D
cant imagine that.

3s and 5700 would be better. I run the 7700 and on 2S it just pulls to many amps. the speed control gets around 180 degrees. The higher voltage and lower kv of the 5700 should work better to keep temps down so you can run longer.

4600 and 3s work best. I have run all of the cc motors, and really think that a s can feigao is better, like a 12s = 3000kv. Just gear it back up to get the speed back...

Ok, next question. . . gearing.

Would I be able to, or even required to change the gearing when I go from a 5700 on 2s to a 5700 on 3s? (T4)

yes, id gear down, and quite a bit too, to keep the same speed and lower temps u will have to gear down 1/3. so if you are running a 20t pinion drop down to around a 13t