E30 Aerodynamics

[BlackbirdM3]

i thought a gurney flap was just to improve stability at speed.

Think about that... Downforce weights the rear of the car improving stability. The front splitter does a similar thing, but up front. If you increase one, you need to increase the other to balance the car.

I admit to this, I've done 140 mph in my M3 (a very long straight road, that wasn't smooth) and I have to say the car was rock solid despite the road being pretty rough.

Will

[jalopi]

I think 1980s BMW didn't go too crazy with the aero on the m3's cuz they knew the cokebinge everyone was on would only go too far with purchases... normal people don't go for cars with massive wings and shit... that was a niche market reserved for lamborghini ;)

[kamotors]

[rwh11385]

rwh11385, what wing is that on the red car? I like the mounting. The uprights look very well done.

I think Brooks Motorsports Composites: http://brooksmotorsport.com/products/

His mentions:

http://forums.bimmerforums.com/forum/showthread.php?1938821-Source-for-wing-uprights-stanchions&p=25714380#post25714380

http://forums.bimmerforums.com/forum/showthread.php?1944088-Brooks-Motorsport-Composites-FOR-SALE&p=25795058#post25795058

http://forums.bimmerforums.com/forum/showthread.php?1693847-Introduction-Brooks-Motorsport-Composites

This cheap stupid stuff was worth 1-1.5 seconds per lap at Gingerman (South Haven Michigan).

splitter is just 3/8 plywood. Wing has a proper airfoil shape (wood ribs with foam core)

Yesssss.

[Eric]

DSCN4019 by ericandshovin, on Flickr

Found another one

[Ether-D]

There's some running them. And IIRC, don't have to spend too much (i.e. ebay) as long as they are structurally sound.

I built that splitter on the yellow car (Treehouse Racing). Worked on Akard's car too. About 9 years ago… Time flies.

[Northern]

Best aero mods for an E30? Pretty simple, look at an M3, all done by the factory,tested, and race approved. The rear window and trunk lid made a huge difference in reducing drag. That alone lowered the CoD from 0.39 to 0.33, front splitter and airdam? Evo 2 airdam with Evo3 splitter. Seal up all the gaps around the hood and grill, (all stock evo parts that can be ordered with little trouble.)

Will

It might be worth some time looking into if you could find a way to mimic that, as well as the m3's under panels around the spare tire well (or cut it out for a diffuser)

I think the gurney flap spoilers would be less effective than an actual wing if we're taking drag into account. I obviously don't have any numbers, but the gurney flap does not seem very aerodynamic, plus it is in the wake of the car and not very wide. A full blown wing will be up higher, wider, with more surface area, and much less drag. On the downside, it will be heavier. Not just the weight of the wing, but the mounts you will need to hold it in place.

[rwh11385]

I built that splitter on the yellow car (Treehouse Racing). Worked on Akard's car too. About 9 years ago… Time flies.

Sweet. I met Jon about that era with the ugly but awesome yellow/green racecar. Bluegrass race weekend 2005, and the sticker was the best part:



I forgot who ran an off the shelf / ebay ricer wing but thought it was someone in e30 world.

It might be worth some time looking into if you could find a way to mimic that

http://www.airtab.com/how.html

E30 are brick-like so could benefit with a few of these near the rear of the roof to reduce drag. Someone should run CFD on this topic. Anyone have an E30 made in CAD already?

[BlackbirdM3]

Vortex generators, yes those might be helpful. The bump above the rear window on the M3 serves much the same purpose causing the boundary layer to trip and spill onto the spoiler. I've sort of wondered what would happen if one were to add some to the existing setup on the M3.

I have to admit it would be fun to stick an E30 in both normal and M3 form in a windtunnel and see what the airflow differences are. Then add things like the EVO front splitter and a set of extra vortex generators and that sort of thing to see just what does actually make a difference and what doesn't.

Will

[Jaxx_]

Thought you might enjoy looking at these autospeed articles:

http://www.autospeed.com/A_111110/hDg34uLtp_1/cms/article.html

http://www.autospeed.com/cms/A_111111/article.html

http://www.autospeed.com/cms/article.html?&A=108656

http://www.autospeed.com/cms/A_2455/article.html

http://www.autospeed.com/cms/A_2456/article.html

http://www.autospeed.com/cms/A_112609/article.html

larger here: https://fbcdn-sphotos-g-a.akamaihd.n...57241711_o.jpg

It was good enough to make a noticeable difference at the top of 2nd gear (max speed for autox territory), but in order to make a real difference you need some fresh air (above the roof line). This was in accordance to the Street Prepared rules(10" spoiler in any direction)

edit: also, minimizing turbulence does not necessarily mean that you are creating downforce. Some of you guys are on the right track with creating laminar flow and removing turbulence. getting rid of(or minimizing) low pressure zones on top of the car will be worth your time. VGs have their limit of effectiveness, and they reach a point of diminishing returns. I think that's outlined in one of the articles I link.

[rwh11385]

http://forums.bimmerforums.com/forum/showthread.php?1251356-Vortex-generators

Since it might not be practical or feasible to change out the rear window and C pillars, a few bucks for VGs might help. Ebay big wing and whatever splitter-like things you can stick on the front.

Im gonna have to have fun and experiment when I get a LeMons of my own.

[Ether-D]

@RWH, I was there that weekend. It was hotter than the devils anus and I was changing tires the whole time I think...

[TobyB]

The stock E30 is drag limited at an absurdly low speed, so keeping drag down may actually
be more beneficial than trying to add download for corners- any gain in the corners can
be more than eaten up in a straight line by drag.
That said, aero download that doesn't cost you much in drag,
especially something like a big front splitter,
will let you readjust suspension settings (in particular, reducing static front camber)
to gain in other areas, particularly braking.

Racing isn't always the best guide, though, as the M3 in DTM was aero- restricted-
sure, they did the best the factory could, but they were restrained by rules that may
not apply to you. Likewise, there is "no" aero development in Pro3 because we can't.
Not because we don't want to.

And Mythbusters proved that you want to dimple it just like the golf ball, didn't they?

t

(ps, a Gurney flap is a way to increase wing download a LOT at the cost of relatively
minimum drag, and since it's easy to change, it's very useful for tuning)

[RoccoB517]

A pretty good explanation of gurney flaps.

http://www.youtube.com/watch?v=TK8-VuwPqq4

[SA E30]