You can find info and a campground map
here. Click on the map to enlarge.
Best bet is one of the Speedway campgrounds. We started out dry camping on the grounds 20+ years ago (area no longer exists) and finished up the last 8 or ten years in the Dragstrip Campground. We had full hook-up spaces above the dragstrip. Last race we went to was Aug 2011.
Many places will require a minimum stay. All of the Speedway campgrounds as well as All American, Red Barn, and Earhart have walkable connections to the track without crossing main roads, but those three can get a bit rowdy.
A few of the church operated campgrounds do not allow alcohol, good or bad depending. There are buses running to the remote parking lots and many of the off site campgrounds.
Almost anywhere you will be walking a mile or more unless you ride a shuttle bus.
Have fun! The August race is a real happening!