Kevin, the way that I like to describe the pits in any land speed event is:
You're welcome to get as close as you want (unless thrashing is going on, of course). But watch out -- if you get too close and look like you're interested - you might hear the crew you're watching saying things to you - like "Hey, you -- would you mind grabbing that wrench and helping us loosen this nut?" I've also heard "Hey, you -- please help out. Here's a towel. Wipe the grunge off that thing over there."
I admit to having done this kind of stuff at the pits. The spectators love to help, too. Be forewarned.