1600 vs 2000 medusa v2

[superek4]

got a question. I raced with a 1600kv medusa 12pinion for 20min temp was 140F, with 50 slip diff.

Today I tried my 2000kv with 11pinion within 11mins the temperature was 176f I had to stop before the motor burn.

What is the advise? Run 1600 higher pinion or 2000 lower pinion?

Hope to get 35mph n above without overheating.