I’m late with this month’s column for the racer’s bible, NSSN, but I have a good excuse. The month of May has proven to be very busy again thanks to the recent IndyCar/Champ Car merger. The added teams have not only increased competition, but also the need to go that extra step to ensure a starting spot for the 92nd Indy 500.
Companies like C&R benefit from times like these by building components to make the cars faster. There’s more energy at Indy than I’ve seen in several years. The fact that all teams are together is a tremendous steppingstone for open-wheel racing.
When every car is a Dallara with a Honda engine, what do the teams do to gain advantage, especially considering this spec has been the same for about six years? The answer is: tune on the given aero package.
Aerodynamics provide the biggest speed gains. The engineers have to dig very deep for these gains and most of it comes from testing in the scale-model wind tunnel.

Aerodynamics provide the biggest speed gains. The engineers have to dig very deep for these gains and most of it comes from testing in the scale-model wind tunnel.

For instance, on the ovals, teams are allowed to build their own suspension. The standard package is a 122-inch wheelbase. Through lots of time in the wind tunnel, some teams have found that a shorter wheelbase creates less drag and develops more downforce.
This is accomplished by pulling the front suspension back, which alters the airflow over the car. At Indy and the other high-speed ovals, teams build 120-inch wheelbase packages. The angles of the aero tubing, which these wishbones are made of, are also very critical for aerodynamics. The 122-inch wheelbase gives the car more stability so some teams will qualify with the 120 inch and switch to the 122 inch for the race.
In 2006, Penske Racing developed a new mirror package that was highly publicized. Instead of the stock Dallara mirrors, they built mirrors that were larger and had a different shape. This mirror shape helped deflect the turbulent air that comes off the top of the front tire away from the rear wing, thus making the rear wing much more efficient. Now, every team uses a version of this mirror, thus taking advantage of a gray area in the rules.
On the tunnel diffusers, which is the air exit of the underside of the car, there are many block-off plates, wickers, etc. that can be used. These plates and wickers alter the speed and direction of the exit air and have a big effect on drag and downforce.
All of these alterations help give the car downforce, in addition to what the rear wing produces. Because of this added downforce, the rear wing can be run at a negative angle, which greatly reduces aero drag. The rear wing is the object sticking in the air and by running the negative angle up to five degrees, the car is much more slippery aerodynamically.
The car still sticks in the corner because of the “free” downforce created by the other aero modifications made to the car.
Because of the added competition this year, qualifying with negative rear-wing angle is an absolute requirement to make the race. In the race, the speeds are slower and the air is turbulent from traffic. Some of that rear-wing angle will be put back for the added downforce in these conditions.
These are just a few noticeable things done to the Dallara cars to make them more aerodynamic. There are hundreds of other “aero tweeks” made by the engineers to reduce drag and make downforce.
At the end of the day, the teams with the most wind-tunnel time have the advantage. Money will always win, no matter what the rulebook says.