Why do v8 racecars, fire a flame from underneath on braking?

Question

i know its the exshaust, but cant they build a bigger exshaust or something

Answer 1

nascar does the same thing. its from the compression in the transmission

Answer 2

It's fuel in the exhaust. They can't build a bigger exhaust for a multitude of reasons.

Answer 3

It's excess fuel getting burned off when they lift off the throttle. You see it because the exhaust headers are short and dump out under the car