Aerodynamic Mods?

[Regnar75]

ive been looking around on here and havent really seen any aero mods like rear diffusers, or underbody flat panels, ive seen some lips act as front splitters, and sideskirts being put on, but has anyone experimented with these for economic/handling/top speed gains? im wondering how well these would actually work (while trying not to obviously look like a modded civic :nice:) and if they would be worth the effort/price.

a little basic knowledge of rear diffusers (cause i had no idea what they did when i saw them on some STI's)
http://en.wikipedia.org/wiki/Diffuser_(automotive)

these guys seem to have some interesting thoughts on techniques of building your own.

http://ecomodder.com/forum/showthread.php/rear-diffuser-build-thread-8313.html

i know what your thinking, but we drive e30s! yes. im looking at the application, not the actual vehicle










has anyone done any of these and had results. my worries would involve possibly hitting a bump at high speeds and catching wind like a kite (unlikely considering i drive an ES ) making the rear diffuser too visible and appearing to look like a punk whos trying to make his car into a super car (im more thinking MPG's and control) front splitter and side skirts seem kind of cool actually. also i wonder about proper cooling, and ability to remove flat panel underbody to work on the car or to use a jack. thoughts comments and concerns?

[Regnar75]

also found this

this is the "new air curtains" for BMW's 1series M

"
Innovative Aerodynamics: Air Curtains
Consistency between form and function is crucial to engineers at BMW who seek perfect balance of various aerodynamic factors in the wind tunnel. As a result, the new Air Curtain is BMW's latest aerodynamic innovation. Introduced first on the BMW 1-Series M Coupe, the Air Curtain will now be a standard feature on the 128i Coupe. The Air Curtain improves air flow around the front wheel arches with the benefit of significantly reduced turbulence. The 128i Coupe can also be equipped with special Aero Wheels to further enhance the performance of the Air Curtain system.
This innovative feature consists of openings in the outer section of the lower front fascia that route high-pressure air through ducts at each front corner. The ducts are approximately 10 x 3 centimeters wide and are designed to channel air to openings at the front of each wheel arch, where it is discharged through a very narrow opening at high speed. The escaping air stream covers the side of the front wheels like a curtain, thereby reducing aerodynamically unfavorable turbulence around the rotating wheels.
Air Curtain has a key role to play in the development of future aerodynamic innovations. An example of the air curtain principle was first presented in the concept study BMW Vision EfficientDynamics at the International Motor Show (IAA) in Frankfurt in 2009, and the developers of the BMW 1-Series M Coupe took on the pioneering task of applying this element to a production vehicle. To do so, they utilized the unique capabilities of the new full-scale "rolling road" Aerolab wind tunnel at the BMW Group's new Aerodynamic Testing Center. Now it has been added to the 128i Coupe."

[Nsquared97]

^This is pretty interesting, what was it that caused them to develop this? Better aero for better fuel efficiency?

[A_Whelan]

....i know what your thinking, but we drive e30s! yes. im looking at the application, not the actual vehicle

You said it yourself. We are driving e30's and we have bigger things to worry about. There may be a tiny percentage on the forums that worry about that and that would be the auto x'ers. The only other people would be those owning other types of cars.

The rest of us dream about an up coming swap, trying to fix that damn leaky steering rack or figuring out why the car is sputtering.

But your post was legitimate so someone might have something.

[Nsquared97]

You said it yourself. We are driving e30's and we have bigger things to worry about. There may be a tiny percentage on the forums that worry about that and that would be the auto x'ers. The only other people would be those owning other types of cars.

As a fairly avid autoXer I would be more interested in this for the fuel economy aspect for my 10 hour drives home from school. Even for a very serious AutoX build, this would be one of the last things I would be worried about.

That said, I'm interested in seeing where this goes.

[ohthejosh]

I know dtmfiberwerkz has a rear diffuser. idk if it has any actual aero dynamic advantages tho.

http://dtmfiberwerkz.com/access/style-rear-bumper-p-56.html

[NigelStu]

I have a bunch of stuff in the works for my racer / chumpcar. All the aero work will be with the intent to reduce drag and increase top speed - With the boxy style, the E30 is at a disadvantage, any reduction will help. We have 3 high-speed tracks events on the Chump schedule for 2012 - 2x Road America and Michigan International Speedway (roval). Front air dam, improved underbody paneling, side skirts, wheel dams and possibly rear diffuser and roof mounted vortex generators. If I could figure out a way to do the front wheel air curtains like shown above, I will. Goal is to minimize the wake behind the car, which creates drag and can induce rear lift.



Take a look under your E30 - BMW has implemented a few aero tweaks, most likely for fuel efficiency (it IS a street car, after all...). The plastic panels in front of the rear subframe, which cover the holes in front of the fuel tank / where pump/filter sit is one - the metal panel running under the drive-shaft. Both of these make the bottom of the car smoother, less turbulence in a very turbulent area. Front bumper on 'is' models have the raised area in the center, lower on the outer edges - this directs some air around/over the car, and some right down the center of the (flat-ish) underbody where is can do the most work.


Are you looking into this more for fuel efficiency gains? If so, there are a bunch of things you can do that will either be invisible to normal people or very subtle. Upgrades over what is currently on the car - Fit a basic air dam, even an inch lower than current, will help keep air from under the car. Small air dams in front of each wheel - just a bit wider than the wheel - will keep air away from the very turbulent spinning wheel area (take a look at most new cars, they will have something in front of the rear wheels). Make sure the front undertray and all other panels under the car are actually on the car. Add side skirts - even just something simple off of the pinch weld. Cover/fill the holes under the car behind the axle. You can also add some rake to the car, or at least make sure the bottom of the car isn't higher in the front than the rear; you want a cone shape under the car, not a funnel.

Improving flow speed under the car can actually help with cooling - faster air moving under the car will draw more air from the engine bay. This is why the front undertray is important.



You have to get sort of crazy for aero to work and have an effect in autoX, since speeds are generally low. Road course, on the other hand, can see benefits in speed and grip. Benefit can be see in fuel efficiency on a road car at highway speeds.



FWIW - I f'n love aero - one of the most interesting and intriguing topics for me. And now, my little brother is working for an aero company; he shows me cool shit all the time. Latest projects for him are working with big semi rigs.

[pacmanE30]

I know dtmfiberwerkz has a rear diffuser. idk if it has any actual aero dynamic advantages tho.

http://dtmfiberwerkz.com/access/styl...mper-p-56.html

that is a pretty good concept, not sure about the function of this diffuser, but the principal is there. This definitely helps reduce drag that is built up in between the tank and the rear bumper. some go as far as "swagging" the rear bumper itself to prevent build up.

[Regnar75]

sweet

some good replies and to think i was worried id be looked at like a crazy. i know the e30 has other things to worry about but i also like to take long trips, and i have always been one to try and squeeze miles out of each gallon. and with my upcoming 1200 mile roadtrip, id like to see what type of effects things like underbody panelling, diffusers (hardest for me to commit to) and splitters will do. plus, if you could squeeze extra miles out of a gallon for some mods under your car, wouldnt you? my current ES valance is low but has no splitter so i might look around for one (which also might look better).

but since im thinking more underside...


i found this interesting article
part 1

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

part 2

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

but to summarize for the lazy folk...

• In a modern aero car, a low front spoiler doesn’t guarantee a reduction in drag.
• About one-third of all drag in current cars results from underside flows.
• Most of that undercar drag is created by the front wheels, followed by the rear wheels and floor.
• Lift is caused mostly by the exterior surfaces, although any positive pressure on flat undercar surfaces will also generate lift.
• A front spoiler positioned back from the leading edge of the bumper is likely to cause lift.

part 2 is all about the tire deflectors in the front, and a custom panel is made that covers the deflectors due to the deflectors at certain sizes creating drag/lift. (while one figure in the graph shows improvement, the actual panel covering the flat deflectors was greater)
these were shown to (at different sizes) be positive or negative to the cars performance.
this was an older prius were aero mods were slightly made to improve MPG
this was the custom build shown actual increases in MPG over the factory mods. (could show why bmw 1m series seems to have done away with tire deflectors in favor for their "air curtain" system. while this custom build seems like a mix between air curtain and the deflectors)

questions comments concerns?

[petrolhead]

Well, aerodynamics are sensitive to pitch, roll , change in ground clearance & so on.. So unless you have a track car with VERY stiff suspension, I'd say forget it.
Another thing is (street-)tyres. Do they generate any more grip with the small increase in load (from the supposed dowforce).

On a different note, I am thinking of making an air dam + splitter and cutting my new rear valance to make room for a diffusor :D

[Holland]

I know one simple areo mod would be the door mirrors. I don't know exactly how much drag they create but they do generate a lot of wind noise.

[Shangsta]

If you are honestly if you are going this far to get better mpg you need to A: Get a better paying job or B: buy a more fuel efficient car

[Sagaris]

If you are honestly if you are going this far to get better mpg you need to A: Get a better paying job or B: buy a more fuel efficient car

I can appreciate where this thread aims to go. Paying attention to the small things can really add up.

[Regnar75]

If you are honestly if you are going this far to get better mpg you need to A: Get a better paying job or B: buy a more fuel efficient car

its not the fact that i cant afford a better car, its the idea of doing something to a car in order to improve MPG or reduce drag. if i wanted great gas mileage i would have bought a prius, but this is about making the car i want, my e30, a little better.
and while i agree downforce will be hard to attain im thinking more along the lines of reducing drag (as stated with the mirrors) to increase fuel economy. this isnt about me trying to turn my ETA into a race car. this is about turning my ETA into an ETA+. if i have a car with a performance limited engine in order to get better MPG why not aid in its ability to get better MPG by doing things such as adding a panel underneath or modified tire diffusers? if i can squeeze another 1 mile out of my car i will feel accomplished and between reducing drag and having different driving habits i think i can accomplish more than 1mpg.:D

am i sharing this dream alone?

[Regnar75]

I can appreciate where this thread aims to go. Paying attention to the small things can really add up.

exactly, thank you