I already have a mazdaspeed rear wing, and was wondering if anyone knows how much downforce/drag it provides at speed? also, I was looking at alternatives besides mazdaspeeds and was wondering if anyone knows how much downforce/drag other wings such as RE amemiya's wings make, and what other options there are for downforce on the front of the car as well.

 

are you actually doing any track driving?

 

I'm with ZZh - what are your plans for the car? Street driving, auto-x, HPDE/track schools?

I'm not really aware of RX-8's having rear downforce issues. For daily driving, including highway speeds, your average rear spoiler does little to nothing to influence the driving experience.

At track speeds, things can change a bit, but not just any wing will provide a real stability/downforce benefit. The majority of wings available are simply for style and provide no practical benefit, especially for street driving. If you are looking for a style piece, go for a wing, but don't expect it to really do much.

Search the forums for any pics of SCCA T2 RX-8s and see what aero aids they're running, if any. These cars see 120mph plus on the track routinely.

 

None of those stylish wings are going to help much.
If you want a real wing, that offers real performance, you can look here:
http://www.crawfordcomposites.com/products.htm

 

The Mazdaspeed wing generates about 200 lbs of downforce at 100 mph in the steepest position. A front splitter will be a big improvement, as is a rear diffuser. Its crucial to get the splitter low to the ground, which can be difficult on a street-driven car. Other things that will help are retaining underbody tray or adding new ones to keep the bottom of the car as smooth as possible. Side-skirts can help some. Biggest improvements will come from a large front splitter and a very large, high rear wing.

 

I have a hard time believing that 200 lbs figure. Though, I don't know what the steepest position looks like. Where did you get that information from?

If it is the case, how much drag is it creating?

 

I believe its from the MS wing instructions. I think the figure was for the MS front bumper, rear diffuser, side-skirts, and wing altogether.

The steepest position of the MS wing is 15 degrees. I suppose you could calculate it if you knew the dimensions of the wing with this equation:

F = 1/2 * span * cord * angle * coeff * ro * v^2

ro is air density, 1.225 at 15 degrees C. V is the speed of the car in m/s.

 

As a reality check, the wing on the 2004 STi is said to generate 90 kg of downforce at 100 kph, that would be nearly 200 lbs at 62 mph.

I tend to leave my MS wing at about 5 degrees or so, because it looks good like that, and produces less drag and better visibility. I've increased the angle at the track and noticed a slight difference on the straight. It was slightly slower to accelerate at high speeds, but I could also feel the rear suspension gradually compress, as if someone had jumped in the back seat.

Also, remember any amount of net downforce is a good thing as most cars will generate several hundred pounds of LIFT at high speeds, so even a net downforce of 50 lbs is beneficial. Anyone remember seeing that FC get airborne at the salt flats in a high-speed run? Or that LMP car get flipped around at Le Mans?

 

I track only a little at the moment, but will be doing much more road coarse type tracking in the future, and when I buy parts I keep this in mind, so I was trying to find some solid info on wings and downforce to find a good combination of donforce/drag for track use