How great are Nascar mechanics and engineers?

After watching Nascar today I have to think the mechanics and engineers that keep 7-800 hp cars going are really great. What more is required to be a Nascar mechanic? How much more is required to maintain an engine that has so many hp and take 110 octane gas?

What are the different types of engineers that work for NASCAR?

I am looking into future jobs and am not sure what kind of engineering I want to do but want to work for Nascar so I need to know the types of engineering involved in working for Nascar.