Is 4S+3S in serie possible?

[Over_revO]

Heres the video,
http://www.youtube.com/watch?v=-i0ludmC4fA

We installed a heat sink on the neu and now it dont overheat for the few sped runs we do, we let it cool down after a couple of runs.

As far as speed , we want the fastest possible without over heating, if it have low kv i will regear. 90-100mph is what we are looking for in some truck we plan to use.

But my primary question was to know if the 1521 would perform as well or more with the MMM on the same setup, we will regear if it dont spin fast enought, i know how to use the speed calculator and the kv rating.

Thx for the help :)