Thinking of building a bl Revo

[maxxdude1234]

For racing you might not get 45minutes out of the 8000's, would probably be closer to 30minutes. Have you considered going with 6s lipo? This way you could run a higher turn motor (10XL), and a 10XL will draw less current than a 7/8XL - hence more runtime, and you can then get 4000-6000mah packs and still make the 20minute mains. This will also put less of a strain on the ESC, motor and also batts - 72amps is fine for a 10XL, but would be pushing it on a 7/8XL.