Before I switched to the Losi camp, I was also having issues trying to mount an LRP Sphere TC esc with fan into the B4 .
( The Losi is almost the same height with fan ) .
The solution I found was buying the Proline Vortex body since it has sidepods
which are higher.
Only thing is you need to put the ESC all the way in the back for the body to pass.
http://www.prolineracing.com/product...B4-174-39.html
Hope this might be usefull.
Erik