Spycraft's chase rules have some considerations for air chases, which I assume would work just fine for an air race with some changes. I don't know if you have seen the rules, but here's a quick step-by-step synopsis.
1: Choose Maneuver.
There's a list of moves you can make, and each vehicle chooses a maneuver. The maneuvers have names like Redline, Force Down, Roll Out, Afterburn, all sorts of goodness.
2: Maneuver checks
Opposed skill checks from all pilots.
3: Spend Action Dice
Spend action dice if you got 'em.
4: Resolve maneuvers and adjust lead
The winner of the role resolves the chosen maneuver.
5: Leads and Obstacles
Add in obstacles, intended as spice. This would represent the pylons in a race, and getting around them is determined by a Reflex save. I think in a race those who miss the save would get a speed penalty, or have those who make it extend their lead.
6: Other Actions
This would be the pilot's other actions, more important in a game where you are firing out a window/etc.
7: Crashes
Apply damage to the vehicle if needed and crash if needed.
In an Aircraft chase, Crash DC's are drastically reduced. I would also re-work the rules for a race so that some of the Maneuvers didn't automatically end the chase if successful, but gave a lead or speed penalty instead. You could also use Critical Failure rules; if you push the plane hard or roll 1's on your checks, the plane risks damage. Add in some ejection seat rules, and you are ready to rock.
