Downforce needed - battle of the craptastic eBay wings

[Jaxx_]

A pro-stock style spoiler would be pretty easy to make with sheet metal, though I don't know if it would have any real benefits. It would, at least look pretty bad ass.

http://www.thesouthernoutlawshop.com...d0b1fbed0d.jpg

those spoilers only reduce drag, they don't produce downforce.

[OniKyan]

A pro-stock style spoiler would be pretty easy to make with sheet metal, though I don't know if it would have any real benefits. It would, at least look pretty bad ass.

[Lurker27]

I'm totally on board with those VGs - I don't think they'd look half bad on the E30, either.

M30 + 4.10 is always gonna be hairy in a light car. That's what I had before I was boosted, and I have 225 star specs (450/500, cabrio front sway, no rear sway). Definitely could step the rear end out at will, especially in the midrange where that mountain of tq lives.

[NigelStu]

by "right" what would you suggest?

height, angle, shape, size and location in the correct place to delay the flow separation that normally happens at the back end of the roof. Testing (like the strings or yarn or smoke) would need to happen to determine these parameters.

This paper from Mitsubishi explaining the little shark-fin vortex generators is one of the best descriptions I've seen on how and why they work.

Mitsu VGs


The roof 'spoilers' (like some BMWs and Subarus have used) work under similar principles, with a similar outcome. Basically, the longer you can keep the air flow next to the body/glass, the smaller the wake and less negative pressure in the back-glass / trunk lid area, reducing drag and lift.

Or in the case of Mistu/Subaru, more clean-flow air hitting the wing element of their clothes-line spoilers.

[irish44j]

both of those things would be good for a 2300lb e30 sitting on tall springs with a total lack of power. Because I do want to do some trackdays in the rally-mobile :)

by "right" what would you suggest?

[NigelStu]

quick related question: is there any advantage to having a diffuser/small spoiler at the top of the back glass/back of the roof WITHOUT a trunk spoiler/wing?

just curious.

If it is done right, it should reduce drag and potentially reduce high-speed lift.

[irish44j]

quick related question: is there any advantage to having a diffuser/small spoiler at the top of the back glass/back of the roof WITHOUT a trunk spoiler/wing?

just curious.

[dinanm3atl]

Yah. Well that is part of the problem. No weight in the back. More torque. Little rubber. Add in a wet track and asking for traction issues out of the corners.

[CorvallisBMW]

195/60r14 on bottlecaps

[dinanm3atl]

Also consider 205s is the widest 15... assuming you are running 15s with the star specs.

[CorvallisBMW]

About 50F and raining. Remember though that we've added weight to the front and taken out a ton of weight from the rear. Couple that with bad geometry from lowering and, well....

[e30bulldog]

thats crazy! I have personally used those tires and its nothing like you described. This is very unlikely but I got a bad set of hankook rs-2's from Tire Rack one time...and they where useless. My e30 probably puts down similar power as that old m30 and I have never had that problem and I figured it would be less on an open road coarse.

What was the temp outside...I know my rs3's are useless at near freezing

[CorvallisBMW]

Actually that is only partially correct.

Spoilers like those in NASCAR do create downforce. They just go about it differently than a wing. Wing creates the downforce with a pressure differential between the bottom side and top side of the wing element. Spoilers create downforce by creating a high-pressure zone on the body in front of the spoiler. This downforce that a spoiler creates is what provides the stability you mentioned. Drag reduction (or increase) depends on size, angle and shape of the spoiler.


There are efficiency, max down-force and drag differences between wings and spoilers, with properly designed wings (airfoil shape) generally providing more downforce with a greater increase in drag.


The important aspect of both is that then need good (laminar) airflow to work properly. Hence the first step would be getting some rear windows in the car.



Corvallis - Do you guys have any extra body panels (from donor cars, or stuff you removed from the car) that you can re-purpose as a spoiler? Re-using parts like that is free per the rules, no impact on AIV. Trunk lid, hood, whatever you cut out of the trunk floor, inner door metal, etc.

Excellent info!

We have plenty of old sheet metal around we could work in to a usable spoiler. Wings would be a bit harder but still doable.

How much tread do u have left on your star specs, those tires are bad about heat cycling out before the wear mark. I have had many sets on my e30, having back tires like this makes the car undrivable.

Also.... How old are your tires???

The tires were brand new in our last race.

[e30bulldog]

How much tread do u have left on your star specs, those tires are bad about heat cycling out before the wear mark. I have had many sets on my e30, having back tires like this makes the car undrivable.

Also.... How old are your tires???

[NigelStu]

hey just saw this thread and I figured I would give my 2 cents. The so called "ricer" wings are actually wings (not saying if they work or not) and the "NASCAR" style wings are not wings at all and they DO NOT add downforce what so ever. They are spoilers, spoilers actually reduce drag and add stability under breaking or transitions. They can be very helpful in a high speed slalom where the rear of the car keeps walking around.

Actually that is only partially correct.

Spoilers like those in NASCAR do create downforce. They just go about it differently than a wing. Wing creates the downforce with a pressure differential between the bottom side and top side of the wing element. Spoilers create downforce by creating a high-pressure zone on the body in front of the spoiler. This downforce that a spoiler creates is what provides the stability you mentioned. Drag reduction (or increase) depends on size, angle and shape of the spoiler.


There are efficiency, max down-force and drag differences between wings and spoilers, with properly designed wings (airfoil shape) generally providing more downforce with a greater increase in drag.


The important aspect of both is that then need good (laminar) airflow to work properly. Hence the first step would be getting some rear windows in the car.



Corvallis - Do you guys have any extra body panels (from donor cars, or stuff you removed from the car) that you can re-purpose as a spoiler? Re-using parts like that is free per the rules, no impact on AIV. Trunk lid, hood, whatever you cut out of the trunk floor, inner door metal, etc.