aftermarket aero for B8

B8 S4
#1

For about $1500, you can buy an adjustable wing for your trunk. I’m unclear on whether you’d do a 61" or 67" application on a B8. The main idea would be to achieve downforce on the rear end of the Audi, which is a bit light with 58.6% over the nose in my car. I’m assuming that the BMW E90 application would bolt onto our cars nicely at a body shop.

http://aprperformance.com/racing-product/gtc-300-adjustable-wings/

http://www.evasivemotorsports.com/mm5/merchant.mvc?Screen=PROD&Store_Code=EM&Product_Code=APR-AS-206757&Category_Code=APR-GT-250

http://www.hpashop.com/images/aHR0cDovL2Zhcm04LnN0YXRpY2ZsaWNrci5jb20vNzA5Ny83MjQ1MTUzNTQ0XzE1ZmM4YzlmMWFfYi5qcGc.jpg

The 67" looks a bit wide.

http://i17.photobucket.com/albums/b79/mlab601/RearWing02.jpg

http://static1.squarespace.com/static/5313f888e4b0d43f6e108742/53c8a72fe4b0cb805d36dc06/53d331d5e4b02e9f4fd416ce/1406349783780/DSC_9176.JPG?format=2500w

#2

A real wing doesn’t bolt to the trunk. Or to be more clear, it goes through the trunk and secures to an actual hard mounting point. The wing needs to bolt to the chassis. Also, I do not subscribe to the idea that weight distribution has anything to do with aero. So the back end of the car being light won’t affect this much. Want cheap aero? Set your car lower with more rake. The windshield angle is a tuning component of overall downforce. The front to rear rake will affect this. Also, being awd, not sure there are any traction issues at our levels of power. The wing will just slow you down. It’s not like the car is real tail happy to warrant it. If you do true aero. Your entire suspension setup and driving style will need to change. The car needs to be setup very loose if you are running a wing like that. Thus the toe out in the back of the TT race car you mentioned in the other thread.

#3

This is an awesome post. I didnt know any of that and good point on the wing actually slowing you down. It would be causing drag all the time not just in the corners. If you set the suspension in the fashion you mentioned will the rake also effect the cars acceleration due to more drag or is this only something where the suspension gets loaded in the corners. Thanks I learn a ton of suspension stuff from you guys

#4

Nah, rake won’t affect accel–unless you’re talking a really, really long straight and even then, it’s not going to be a very big margin.

BTW windshield thing. I didn’t illustrate this, it’s from another site:
http://www.gmecca.com/byorc/images/liftdownforce.gif

FWIW not the same application, but scale hobby rc cars (lol yes, i went there) have been aero testing bodies with different windshield locations (ie: cab forward vs cab rearward), and the difference in downforce + how it is applied to the car is yielding a big difference. But anyway, my note on lowering the car had to do with reducing the air going under the car. Less air under there, less lift. Also, if less air is going under, it means more air has to travel over the car - this is where i went into the whole windshield thing.

#5

Continuing to pave new ground on this platform, I like it.

#6

So if one were to do this, they’d really want to build a brace in the trunk like this. And then bolt the wing to the brace, rendering the trunk lid closed permanently and inoperable. That’s do-able.

http://i72.photobucket.com/albums/i167/nocab72/E46%20M3%20Build%20-%20Black/WingMountBrackets.jpg

#7

^yup, that’d be exactly right.
Though people who go this route (see trackhq.com boards) are struggling with crazy understeer problems–even with a proper alignment. You really need front aero too if you go with a proper rear wing.
Front aero as in, a legit front splitter that you can stand on.

#8

So let’s say the range of adjustment is 0 degrees to 15 degrees. At 15 degrees perhaps it makes an absurd 400 pounds of downforce at 120 MPH. What if you just wanted to make 100 pounds of downforce at 120 MPH? Could you just set it to like 3-4 degrees?

#9

It’s very messy to manage because a wing’s angle of attack not only determines downforce, but when it is actually effective. A wing with less AOE may provide less maximum downforce, but would also be effective at a much greater range of speeds (read: it still works at lower speeds, whereas a high AOE would not work at low speeds). So you are now going to deal with juggling aero induced understeer over a wider speed range.

#10

Yeah this looks like a can of worms I don’t want to open. Now I know why Porsche charges $5000 for the aero kit, as a factory option on non-GT cars.

#11

Yeah, Aero is a whole new can of worms.

Great discussion on this thread though. Love reading this kind of stuff.

#12

There are some great articles about the new Viper ACR. Dodge did a press day where they had journalists go around the track with two different aero setups. The top speeds (lower) and cornering grip (faster) varied hugely lap over lap.

#13

This is on sale for $399 now. I wonder if I can stack two of them together to create a lower hanging lip.

http://www.modbargains.com/DTM-Style-Carbon-Fiber-Front-Lip-B8-S4-A4-S-Line.htm

http://www.modbargains.com/images/Products/JL%20Motoring/DTM-Style-Front-Lip-Audi-S4-B8-Black%20(3).JPG

#14

West, consider buying the one from jl motoring instead. Someone local to me bought the mod bargains one and while they are supposed to be the same type of lip, his looks like a cheap knockoff… The jl piece is a bit more but they are made to order and I was impressed with the fitment and quality of my piece. Here are a couple pics on my car to show fitment. Idk if it truly does anything in terms of aero…
http://images.tapatalk-cdn.com/15/09/02/5563b206e4914ded79a83ef214eef353.jpg

http://images.tapatalk-cdn.com/15/09/02/71fe7a44a5bf210044dcbb428e8f41ad.jpg

#15

Interesting conversation. I like reading about all of this. Especially because in a few years i want to do this with a TT.

#16

Are you seriously considering gluing two of those together? I’m sorry west, but that sounds ridiculous :smiley: (unless that is straight troll bait and I fell for it…)

You should just track down these guys

http://fourtitude.com/wp-content/uploads/2014/11/2014-SEMA-Show-week-audi-817-600x375.jpg

#17

Thats not a bad price. would this actually be functional or more cosmetic.

#18

That modbargains splitter would do almost nothing for downforce, but potentially further damming air from flowing underneath could be useful if the car was fully sealed underneath and raked for downforce, with a functional diffuser at the back. I know of an NSX with a lot of functional underbody aero/flat bottoms, even out of necessity to avoid the rear bumper generating drag and even lift.

That show car had the right looking splitter and wing, but that guy can’t be serious - looks like a tuner show car. The flip-ups for the tire poke even…lol! Wonder if there’s anything structurally functional there or if it’s just someones DTM dream.

#19

That car was a sema show pony lol 355mm r888’s

#20

Holy crap 355s lol. Can’t see those wheel bearings lasting more than 5k miles :-). Il bet it would get its ass handed to it by a stock car with an alignment and 245 R6s. Or maybe even a plain ass stock car…