Hi guys,

I've read quite a few threads on here about aerodynamics and the consensus is that the angle of the rear spoiler should not exceed 7-8 degrees otherwise it will "stall". I'm also not clear why it should not be above the roof line.

(i) How do you know when the wing will stall ?

(ii) I wanted to put on something like the E30 M3 DTM spoiler but this seems to go against what you guys are saying, yet the E30 M3 won championships with the help of superior aerodynamics even though they were down on power compared to the Mercedes.

The E30 M3 DTM spoiler was almost 90 degrees. (sorry, not allowed to post links to pics)

Please advise.

I've read quite a few threads on here about aerodynamics and the consensus is that the angle of the rear spoiler should not exceed 7-8 degrees otherwise it will "stall". I'm also not clear why it should not be above the roof line.

The stall angle is totally dependent on the wing design. Some designs may stall at 15 degress while others can run at 45 degrees...just depends on the wing shape.

As for the roofline...rules are the only reason for not going above it. If the rules allowed, I'd run my wing higher than the roof.

(ii) I wanted to put on something like the E30 M3 DTM spoiler but this seems to go against what you guys are saying, yet the E30 M3 won championships with the help of superior aerodynamics even though they were down on power compared to the Mercedes.

Those cars ran to a VERY specific set of rules. Unless you are running under those same rules, there are much more efficient options for gaining downforce in the rear. Keep in mind that those cars were run 10+ years ago as well.

Thanks B. Watts

If you were in my position, what would you put on the car for maximum downforce front & rear ? The car will only be run on open days at tracks, there are no rules or restrictions. Lots of body parts will be replaced with carbon fiber, so the car should be very light (car has no interior). I also want to build a CF rear diffusor. The car's track is going to be widened by about 60-70mm per side and receiving a KW Variant 3 race suspension.

I've got 325mm brake discs in front with Wilwood 6-pot calipers. Tyres are 245s semi-slick all round.

In your opinion, does the E30 M3 DTM boot spoiler cause a lot of drag ?