mountainbiker2

I have no pictures of it, but it was originally on a very fast autocrossed BMW. He bought a new one from Dauntless racing. He's selling his used one pretty cheap. Most of our autocross tracks are between 30-75 mph. My car is well balanced right now in those speeds. My thinking is that with no splitter I might get a little more understeer. If I raise up the back or put on a bigger rear sway bar to compensate for the wing I would gain grip back in the front and the wing would give me grip in the back that I lost from the bigger sway bar. Net grip more all the way around. What do you guys think?

thanks,

Steve A.

John Shiels

I think at those speeds you will see little difference with a wing. What is your average speed around the course, divy length & time?

steponc

In most of the faster classes a clear lexan spoiler can be seen. It is attached at the trunk with a hinge and turnbuckled to the top for angle adjustment. Most of them are at a steep angle to put down force on the rear. I'll see if I can find some photos.

RacePro Engineering

Steve,

Essentially agreeing with John here, unless you spend a significant time above 60 MPH IN TURNS, a wing will be of negligible value for a car weighing as much as most 'Vettes. The additional grip generated by downforce comes at the cost of added drag. If you are attaining 60++ miles per hour only on the straights, the device will probably slow you down!

Ed LoPresti

mountainbiker2

All the top TIME guys seem to run them. I don't know if one just copies the other, and before you know it, everyone has one. I believe most average speed is between 50-60 mph. I've seen the dual element, and spoiler ones split about even. I just have the opportunity to buy the dual element one. I definitely don't need to waste time or money on something that doesn't work. Thanks.

John Shiels

Take the time and the length of the course for you speed average. How many turns? As said above it is drag on the straights and little value. They have wings but they may be fast for other reasons. I would think you could spend the money better elsewhere.

RacePro Engineering

Hi Steve,

While still agreeing with John,

GENERALLY SPEAKING - At autocross speeds, the cars benefiting most from aero devices are the light-weight modified classes. They usually have plenty of power to overcome the added drag, and their light weight and big slicks allow them to carry lots of speed through the turns, thereby making their aero effective.

From the other perspective, IF one is looking for an effective aerodynamic device, one that will start to "come in" at slower speeds, and is capable of generating high downforce, then your dual-element wing is a good choice. Angle of attack of the main element, and the "hand-off" to the flap, will be important aspects to get right.

GENERALLY SPEAKING - A true wing will slow a car on the straights, allow more secure braking (on its end of the car), and add grip in turns (again, on its end). The rear spoiler, to which steponc refers, CAN improve straight line speed by reducing turbulance immediately behind the car, but it has to be set at an optimal angle. These usually generate very little actual downforce, but do stabilize the rear in the turns, again by helping to manage the turbulance.

In the scheme of things, grip, weight, power, and stiffness are the pieces to optimize before aero. That is the way we think of it.

Ed

RX7 KLR

That is because the Street Prepared Solo classes don't allow a wing, only a spoiler.

Most of the people running wings (Street Mod, Mod, XP classes) are doing so for high speed stability during slaloms and fast lane change maneuvers.

I have seen data from one cars SSM solo wing showing 300lbs of down force at 60mph. The data also showed a very minimal HP number to overcome the drag, something along the lines of less than 30hp. *this was all years ago when I was on the SEB and the total wing size/area rules were still being worked out.

Do they work, are they needed to win? Lots of cars have won without them... But if it makes you more comfortable chances are you will go quicker with one.

Hey Steve, skip the splitter. Go all the way.

Solofast

Downforce devices absolutely work, even at autocross speeds. It isn't that it will transform the car but as speeds increase rear drive cars oversteer more. This is because you are using more power to drive the car through a corner as speed increases, and that power increases the amount of oversteer.

A good wing can calm the car down a lot in fast transients and places where you lift, and that can make a big difference. With an autocross car you are setting the car up to avoid too much push and as you go faster, having the rear tied down can calm things down a lot.

We absoutely noticed the difference with a Street Prepared legal spoiler on our BSP car and a wing will help even more.

RacePro Engineering

Wow! Do the Formula 1 teams know about this? Maybe a quick verification of the instrumentation would have been in order . . . . .

Ed

RX7 KLR

With the lay down wings they have been using I doubt they are interested in that much down force.

Foilsim was used for a lot of data, at the time there was not a wing area limit. With the current SM max allowed (8sq'), and a lot of rake, 200lbs at 45mph was achieved with a multi-element wing - with no max area a lot of models that were proposed produced even more.

Certainly in the real world these numbers will vary, but most solo guys will have to rely on sim numbers until wind tunnel time gets a lot cheaper.

John Shiels

http://badboyvettes.com/main/display...C5&p=01_sm.jpg

autoX car

RX7 KLR

You call that a wing. How about dual element full carbon.

Actually, taking a page from the good Dr.s' car, I think Steve needs to find a way to make the vette skinny. This is 476hp/403tq, and a 315 rear tire neatly tucked within the fender. Steve's car should be light enough now to use a smaller tire, and with a stockish engine it can't be making that much power. The smaller tire will heat up quicker, weigh less, and give more gearing advantage off the corner.

John Shiels

Still think money on suspension is better spent if it fits in the class.

TLGunman

I always found the UofMissouri-Rolla's research interesting:

http://legacy.ensight.com/images/sto...ories/fsae.pdf