E30 Aerodynamics

[kingston]

I cut out my spare tire well and made a custom diffuser out of alumalite that goes from the diff to the back roll panel and from shock to shock, sealing up the whole bottom.


I need to get a better pic of it later... just snapped this one real quick

Saw that on your other thread and posted there :)

[ncrmtrsprtsE30]

Love the exhaust. Is the bumper ever going back on?

thanks! nope bumper is staying off, too much weight. lol

fucking cool^

:up: thanks!

Really like that exhaust look, how it comes straight out of the bodywork makes it look like it was meant that way, not just improvised.

Yep, I just need to put a heat shield around where it comes out so it looks cleaner.

edit: for pics.

[e30_302]

That looks nice, should really help cut the drag back there.

[Revzillia]

New car with aero

I just bought this car. It s a proven champion winner so the previous owner has it fiquered out I'm going to be talking to him about the aero and what changed with the car. Jc

[kingston]

Nice car!!

[Fidhle007]

[Fidhle007]

[325est13psi]

thanks! nope bumper is staying off, too much weight. lol


:up: thanks!


Yep, I just need to put a heat shield around where it comes out so it looks cleaner.

edit: for pics.

dont let this thread die!
how much did you spend on that rear diffuser, alumilite is not cheap!
i made my front splitter out of it $100 later

[Eric]

Is aluminite available locally?


Sent from my iPhone using Tapatalk

[catboy]

Reading this with interest to see if there's any tweaks I could apply to my e36..

quick comment on the above - you might find you're actually creating drag with this diffuser, assuming the front edge is open?
Might be worth making some holes either side of the exhaust just above the diffuser to let any air out which is above the diffuser plane? Or you could extend it all the way through to the front splitter, but this is much more work and might cause problems with the exhaust system and diff oil temps..

[2mAn]

bumping this back up because I am trying to keep this type of discussion going...

I am interested in the rear aero stuff around the spare tire well and rear bumper. I want to fab something like that for my track car.

Those are just the standard M3 plastic filler pieces. You'd have the come up with your own pieces and a way to mount them onto the valence.

regarding the pic above, is it possible to fill those voids on a regular E30 with ABS plastic to make it more of a flat bottom. Obviously something like this would need to be paired with rear wing and some type of front diffuser.

Up front, I want to create something that will connect the iS lip to a red46 skidplate, then behind that I want to put the transmission skidplate back on.

The idea is not to make the entire bottom flat, but to eliminate as many voids under the car where air can tuck in and create lift.

Also, I had a link to those vortex generators on the first page and they were only a few bucks a pop. I want to buy 5 of them to mount to the roof. I have been trying to get my hands on a M3 C-pillar cover, but it seems like a fruitless endeavor so Im going to try a different, more modern aero approach

[e30_302]

My concern with a flat bottom is heat management. Of course we do endurance racing so it may be more of an issue for us than others. A deep air dam and side skirts are low hanging fruit with little downside.

[e30_302]

Here's my hooptie

[2mAn]

My concern with a flat bottom is heat management. Of course we do endurance racing so it may be more of an issue for us than others. A deep air dam and side skirts are low hanging fruit with little downside.

I know that RoccoB517 has a full flat bottom on he has seen a rise in diff temps, but I think I want to leave more exposed than he did. His is a complete flat bottom with a single NACA duct by the diff and a few other openings.

I added a full flat bottom and diffuser to the aero package, and let me tell you, it made a HUGE difference.

This is an amazing thread. Funny Ive been reading about aero underbody stuff and nobody has gone to the extent you've have (or at least shared it here). The only thing Im wondering about with the underbody stuff is the trans and diff temps, have you seen an increase? I noticed a NACA duct style for the diff

I do think the diff temps are getting higher than I would like. I will be installing a diff cooler during the off-season this year. I haven't had any issues with the trans. I have been keeping an eye on the fluids, and it seems like the trans fluid is doing okay and the diff has to be changed more frequently with the lower amount of airflow.

I noticed the difference in the way the car felt in the very first lap after installing the flat bottom. The aero load from the wing and splitter definitely increased, and the car feels less "floaty". Sometimes inconsistent track surfaces at speeds north of say 90 mph would cause the car to bob a little. It stays flat now.

The next time I have the under tray off I'll snap some pics of the mounts for you guys. It's really just simple 1" flat strap bent into an L shape. The bottom has a nutsert to allow the under tray to be bolted up, and the other end is a single 1/4-20 nut and bolt through the pinch weld at the bottom of the rocker. I basically created mounting points that clear all of the mess under there, and they attach at the same points as the side skirts.

I love what he's doing and I hope to adopt some of his tricks. Heres his thread

http://www.r3vlimited.com/board/showthread.php?t=341125

[TobyB]

I want to leave more exposed than he did.

It's all or nothing-
if you leave something to cause turbulence, the air will very seldom reattach.
It has to be smooth from in front of the front bumper/air dam.

And incremental gains are made from the front back, as in, if you smooth to the front doors
you gain some, if you smooth to the rear axle, you can get more,
and if you smooth all the way back, then something like a diffuser starts to become
predictable and possibly even tunable.

I read a few books a long time ago...
t