Quote:
Originally Posted by RC toy
ERBE with 1515 2200 kv and 18.84259 : 1 total gear reduction(65t spur , 18t pinion) on 6s reaches 50 mph
If I go to 1518 1800kv then to have the same top speed I need to change spur to 54t. In chase of that I get 15.65385 : 1 total gear reduction and that's a way lower. 
I can't believe that with gear reduction that low I will get beter runing times  |
Have faith ;)
The amp your motor will eat does not depend only on the gear reduction, the 1518 will produce more torque for the same amp rating, that's why it will consumme the same current for the same top speed than the 1515.
More over, the 1518 will have a better efficiency because it will handle the same power in a bigger size and at a lower RPM, so longer runtimes and lower temps ;) I warranty you the result ;)