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Conor Daly’s car gives us a better view of the rear guards. Honda uses the rear bulkhead of the guards as bracing. The horizontal braces also have small Gurney flaps built into them, not only making them much stronger, but also increasing downforce. The spars connecting the guards to the rear crush structure also have Gurney flaps. As we will see later, the diffuser itself actually ends at the gearbox (the carbon fiber piece you see here is actually a crush structure), but Honda has used the back of the transmission and the guards to help extend the usable length of the tunnels. Conor’s car is very unique in that his Smithfield sponsored car is powered by Bacon!
The Chevy wheel guards are very barren compared to Honda’s. With only a single airfoil shaped brace in the middle and a panel up top, the rest of the wheel guard is very open. Once again, Chevy uses the wheel guards to direct flow off the diffuser.
The most curious detail of the Chevy body is this gap in the sidepod. My theory is the sidepod has a rather large volume of air running through it (as shown by the large radiator intakes). This creates a vacuum and sucks air off the side of the car, diverting it over the floor. This would also help reduce turbulence by directing air off the rear wheel. The rear wheels are nearly fully enclosed by the sidepod and wheel guard. You can see a triangular panel on the inside of the wheel guard. Some Chevy teams were running this panel, while others were not. I’m not sure what the benefit of this panel is, though it seems removing it would reduce drag.
Simon Pagenaud was running one of the cars running without that extra panel. The crush structure in the rear is a Dallara piece, so both use the same wing mounts. These low mounts are where angle of attack is adjusted. We noticed at least one Chevy had its wing laid back to the point where it looked like it was actually producing lift!
We were able to catch a peek of Jack Hawksworth’s car with its pants down i.e. with the wing and rear guards removed. Here we can see the tunnels under the car. We can also see a cutout in the inside of the fender, likely directing air over the diffuser. You can see how the rear wheel guards will add almost a foot to the length of the tunnels once installed.
