Well I have begun racing my 1/8" scale. Have you found an ESC that can handle the heat?? I have a fan on my motor and it stays WAY cooler than my esc (8XL 4s lipo 9920).
Today I could only race 5 to 6 minutes with 13/46 gearing on a hyper 7 then it would thermal. after 5 minutes the esc was 155' f. Speed is where I want but it just gets too hot.

Anyone want to buy a 9920?? I am going to get a Quark 125.