brushless xxxt and gearing

[tonka truck]

Thanks mike for your help with this setup. I took it out last night and it flew, even on cheap six cell 3300 nimh stick pack and had excellent run time. The amount of dust it threw when I got it do doughnuts was v. cool.

Anyway the point of the post was to ask about knowing what the right gearing would be.

I am running 17/88 at present and at the end of the run the 4200 was warm (could leave my finger on for good 5 secs). I was pulling 37 amp peak using my 'watts up meter'

Whilst I am running 6 cells, I will mainly be using 7 cells (GP 3300), so will I need to go up or down in pinion size?

Is using a temp gun a good way of checking the right gearing?