I was looking through an old cra program from 1973, and a few cars had Turbo-Offy 270 under engine, while every one else's said Chevy or Chevy 427. Does anyone know what kind of engines were these?

They made the 110 Offy for Midgets and the big engine for Sprint cars. At Indy they started turbo charging them in the 70's and before the restricted the boost to 80" and they had unlimited boost, they were getting upwards of 1,000 HP out of them. The Ford Cosworth ended their domination in the late 70's though...