In Indy 500 tradition, the final practice session before the big race -- on the Friday before race day -- is "Carb Day." The name alludes to a bygone era when teams' had "one last chance" to tune their carburetors. These days "Carb Day" is a festival, with sponsors, spectators, and even a concert (this year it's The Steve Miller Band and Barenaked Ladies). But more than that, it's the day Indy pit crews get to compete in their own "sport within a sport."

It's the "TAG Heuer Pit Stop Challenge," and race teams like Chip Ganassi Racing will compete in a single-elimination challenge in which two cars line up, drag-racing style, in a dual "pit box." From a standing start, cars race in, crews change four tires and simulate a refueling, and drivers race to a finish line 200 feet away.

The event is an acknowledgement that pit crews, like the guys from Ganassi who let us into their training space to see how they prepared not only for the pit challenge, but for the most important pit challenge of all: the Indy 500. Unlike NASCAR, whose pit crews largely comprise ex-collegiate football players, IndyCar crews must be mechanics first. That's were Ganassi team coach Chris Snyder comes in. Snyder, a former Penn State defensive end, trains the crews at an on-site gym and runs through pitting drills several times a week.

The point is consistency. While airjacks lift IndyCars up manually, unlike F1's manual jacking, the cars' refueling takes an inflexible seven seconds. Crews constantly evaluate their performances, using helmet cams and spreadsheets of data, to help them stay close to the limit as possible. Needless to say, in pitting, screwups can mean the difference between a win and second place.

Check out the video to see how they train for the big show.