Title pretty much explains it - do vertical side skirt extensions help with aerodynamics? What are the advantages/disadvantages of having them? Is it possible to keep TOO much air out from under the car??

In autocross, some of the AMod cars have thick rubber spring loaded side skirt sweepers that basically drag on the ground, sealing off the airflow. The spring mechanism keeps them in contact with the ground as the suspension moves, while minimizing the friction drag losses. . .

If you are allowed to use them, is there any reason NOT to use them?? I saw them on the Cyber EVO - that's what made me think about using them on my car.

EVOlutionary

 

The downside would be inducing an aero imbalance due to not having the design and testing capabilities to properly sort out what is a very complex system. The upside is that if you can and do get it right there is real tangible improvement in grip even at moderate autocross speeds (and above, huge improvements).

 

The design of the car plays a vital role in the effectiveness of skirts. Ideally, one wants to obtain lower pressure under the car by either speeding up the flow or simply removing the air. Skirts are used to block flow from entering or leaving the sides with the purpose to retain low pressure by sealing to the ground or aid flow speed by minimizing flow through the sides.

Without testing a particular vehicle, I would guess that skirts would make minimal difference at low speeds without use in conjunction with other aero devices under the car such as splitters or diffusers. As speeds increase, however, they may have greater effect by themselves.

And as with any aero device, airspeed would need to sufficient to provide the force required to make a relative difference on something as massive as a typical sports car. I would really question effectiveness at improving low speed handling (such as during an autocross). Of course there are also high speed autocrosses.

So...reasons not to use them? Well, unless they can be proven to significantly improve things for autocross on a particular car model, it's probably a *much* better idea to spend the time/effort/money on improving driver skill.

High speed aero as is common in road racing is another matter. And especially in time attack where it's flat out and the best drivers need every hundredth they can get. But in most cases it's even still likely a better choice to first improve driver skill after the basic safety mods are in place.

Cheers!
Ethan

 

Dont know how much of a difference they would make for autocross. Heres my friends 944 turbo with them.

 

now that's a wing, worthy of a 747

wouldn't he fair better with a trip right at the rear window edge? along with the wing.

 

Nice. Something like that is what I'm thinking of.

 

same thing with nascar, it prevents lift at high speeds. it prevents air getting trapped under the car where it doesnt pass smoothly because of all the stuff under there where the air creates turbulence and lift.

 

Seems like it could help but one would seriously need to consider a splitter, undertray and diffuser to get the full effect.

Speaking of which, I'm sure someone is doing these things but who and lets see some pics. I know several guys in the 240 crowd who are doing it for time attack with some interest in less aggressive systems for street/track day use.

 

Splitter - check
Diffuser - check
undertray - only 1/3 of the underpart will be covered - check


The only EVO I have seen using them is the newest Cyber EVO. They are white.

EVOlutionary