Rustler speed attempt...

[What's_nitro?]

Well, in the "real world" it's rated for 6s. I can't understand why you would try to run it 33% over the rated voltage. I take it you will run the same motor? Same gearing? If one of those doesn't change it's gonna be toast. If not when you accelerate, then when you brake. Sorry to sound so "glass half empty" but you're basically testing to see whether you can waste $220. $150 for the ESC and $70 for the replacement. Plus shipping.