3900kv vs. 13.5t
 

im still new to all of this brushless stuff, anyhow i had a cc 3900kv motor in my 10th 2wd rc10b4 and recently installed a 13.5t because my local track is probally going to a 13.5 mtr limit for this class. the kv rating on the 13.5 motor says its 2500kv. the 13.5 has the same boost as the 3900kv but the top end speed is not even close to the 3900kv motor. should there be that big of a difference in the two? i upped the 22t pinion to a 24t w/ the same 81t spur.

Sorry to not have an answer but I'm interested too. I have the Element by Castle combo in a XXX-T CR which is a 3900kv 4 pole motor. I want to start racing and I figure I should start in the stock 17.5t class...but the more I read the more I think it is going to be WICKED slow compared to the motor I have now.

To achieve the same speed with a 2500kv motor as a 3900kv motor your pinion would need to be 55% larger

22t with 3900kv = 34t with 2500kv

Cheers

The main reason most tracks "spec" a motor class is so that everyone is on the same playing field and you don't have to take out a loan to be competetive :D You're truck shouldn't be any slower than anyone else in your class. I'm running Stock (17.5) with the T4.1, 28/75 gearing. I wouldn't call it slow by any means, but no, it won't keep up with my SC10 with 3800 4 pole.

I think once you start racing Stock, you're going to enjoy it :tire:

Good luck!

Oh I know it's about a level playing field and I'm sure I will have a great time...if I can just find a damn track to race at that doesn't take all day to get to. Even better if it had something for the family to do near it.

you will like the 13.5 better than the 3900...most likely, the 13.5 will be sensored Meaning the powerband will be alot smoother than the no sensored set ups.

13.5 is plenty fast on a track. i run a 13.5 vector x12 Lrp and a SXX v2 on my blitz ese and its plenty fast.

the 4 pole 3900 has a lot of torque compared to the 13.5