E30 Aerodynamics

[pmachan]

I got a couple things brewing, more pics to follow once I finish the rear set up.

What lower valance/splitter is that? Looks like an M3 one, I need something similar for my non-m e30.
I have a decent wing, but nothing up front, and I need some help there for sure.

[stealthbeam]

What Over fenders are those?

[Wolfman]

What lower valance/splitter is that? Looks like an M3 one, I need something similar for my non-m e30.
I have a decent wing, but nothing up front, and I need some help there for sure.

Factory "is" front lip with "Ryan G" splitter

[TobyB]

The flares look like the IE version of the 2002 turbo flares...

t

[SOneThreeCoupe]

Bump.

Anyone have any updates to share? This thread was great.

A piece of formed lexan spanning from bumper to leading edge of the hood would help reduce some of the pressure build-up- the M3 Evo bumper seal probably helps this a little without looking like a bag of smashed arseholes.

Venting the front fenders (by cutting at about halfway between body line and trim and bending inward) would be a plus, controlling airflow into and out of the radiator (and the engine compartment as a whole) would be a plus, fences on a larger (as big as the rules and aero balance allow), flatter (depends on whether or not the car sees puddles on track or is soft enough to bottom) splitter would be a plus, spats to keep the leading edge of the tires out of airflow would be a plus, smaller mirrors would be a plus, no wipers or single wiper conversion would be a plus, smooth trim with no indicators or plate depression would be a plus, skirts, partial undertray and fences to the "frame rails" would be a plus, welding the fog light holes closed would be a plus, a modified Hartge H35 front airdam would be a plus, headlight covers mounted flush with the grille would be a plus, bigger wing end plates would increase efficiency of the wing allowing less angle, etc.

You can always just add horsepower but a lot of the above is fairly cheap. Even the 1/16" alloy sunroof delete panel with rivets is draggy and reducing the efficiency of the rear wing.

No matter what you do, never, ever use wire in airflow to brace a wing or a splitter. It's silly draggy.

[TobyB]

Personally, I love the airfoil- shaped strapping and tubing
that experimental planes now use instead of wire and pipe...

t

[haaken675]

So I am finally getting to the point in my build where I can actually think about aero. I plan on doing a front splitter, rear diffuser as I no longer have a spare tire well, and a gt wing. Does anyone know if it makes a big enough difference in wing height? I was looking at an APR GT-250 or an APR GTC-300, but it looks like total height is somewhere around 13 inches. Roofline is somewhere around 17-18 inches. This height is achieved with their standard 11 inch pedestals. Apparently that being said, they offer a 14 inch pedestal that I could custom order that would likely bring the total height to around 16.5 inches.

Would that work better, especially if I went with the 2d shape of the GT-250 wing?

[FRODADDY]

Driven on track is there a noticable difference between no spoiler and the OEM spoilers?

[ak-]

Driven on track is there a noticable difference between no spoiler and the OEM spoilers?

The OEM 'is' spoiler? There will be a difference, but you'd probably have to be acquainted with the feeling of driving the car at its limit all the time to notice (probably still won't lol).
Spoilers redirect air that causes unfavorable behaviors like rear-end lift at high speed. So I'd rather have it on and not feel anything, than have it off knowing it's not doing anything.

[ForcedFirebird]

Driven on track is there a noticable difference between no spoiler and the OEM spoilers?

No. I have driven e30's to terminal velocity (~134mph with no draft, ~160whp) and there's many other things that cause the car to feel "light" than an OEM spoiler. Funny thing is, though, if your car was NOT equipped with one, you get points deducted for them in Time Trials, which makes no sense to me.

[Digitalwave]

The spoiler doesn't produce downforce, it reduces drag on the rear end. It wouldn't make the car feel light if you took it off, but perhaps it would lower your top speed by a couple mph. That said, it is probably a very small difference.

[nando]

I saw somewhere that BMW claimed a 5% reduction in drag. It's probably worth a few MPH easily, but yeah, it doesn't have anything to do with downforce.

[ForcedFirebird]

The spoiler doesn't produce downforce, it reduces drag on the rear end. It wouldn't make the car feel light if you took it off, but perhaps it would lower your top speed by a couple mph. That said, it is probably a very small difference.

Sorry, I was getting at it feeling "light" without an OEM trunk lip.

I saw somewhere that BMW claimed a 5% reduction in drag. It's probably worth a few MPH easily, but yeah, it doesn't have anything to do with downforce.

Would be fun to do back to back experiments. We do Daytona pretty much every year. Unfortunately keeping the cars fueled and full of drivers are more important. I can say a 4.10 vs 3.73 doesn't matter much, the cars are aero limited in stock form. I've driven identically built cars, with and without the OEM the lip and didn't notice, but am also a mid pack driver. :/

[Motheye99]

I'm sure it's very minor on E30's but isn't a rear lip also designed to keep a car stable at high speed, not in the way of down force. But increasing the drag on the car in a predictable way. I'm not very knowledgeable on car areo but we use devices very similar on rockets to increase "base drag".

Sent from my SM-G950U using Tapatalk

[ak-]

Hope you guys didn't think I was talking about downforce when I said an absent spoiler can create rear-end lift. Spoilers aren't for downforce, correct.