Aero mods for chumps...

[Vanquizor]

Looks like my post count is high enough.... here come the pics ( pre-teardown)









From this point the entire car has been taken to a frame.

What I'm thinking for the front is something like this:



Of course with the splitter, and possibly closing up the upper grille as long as I still have sufficient airflow through the rad. Also it will actually cover the front of my tires.

[botsapper]

Love the faux-Sube WRX STI black headlights, roof hood scoop, mudflaps and even the blue & yellow livery. No big wing. The cage looks very sturdy but makes any 'open' airflow, very dirty. Still recommend a clean 'closed' sedan.

A large front dam is a good start. (Getting a cheap used SRT front clip?).

Many ecomodders here, have already done this DIY. Home Depot deep front/side skirts, with garden edging.
DIY home depot lip. - SRT Forums - SRT4, SRT6, SRT8, SRT10 & Dodge Forum

Coroplast panels (used political signs) for sealing any/all openings.

If you got any sheckels, fabrication skills & ambition left, a DIY 'fastback'.

DriftCentral Forums • View topic - Miata Fastback
http://www.period13cobras.com/jes/warhorse/DSC02551.JPG

[BamZipPow]

Another low cost and lightweight material instead of coroplast would be luan...about $10 a 4'x8' sheet.

[Vanquizor]

For the front bumper I wasen't going to anything that slick, simply cutting the stock bumper cover just above the grille opening and butting a big ole chunk of 18g aluminum to the body seam before riviting it in place.

Something like this:



P.S. the headlights are headed for the recycle bin.... if you want them cover the cost of shipping

[botsapper]

...nice and simple fab solution (trim w/ 'flower' edging). If you got extra alu, make rear wheel well covers (made removeable w/ Rivscrew speed fasteners). Now, if you got plenty, form yourself a cool (w/ lexan rear window panel) fastback !!!

[euromodder]

Originally Posted by botsapper

Love the faux-Sube WRX STI black headlights, roof hood scoop, mudflaps and even the blue & yellow livery.

The hood scoop and the mudflaps aren't helping the aero though.

It also lacks the driver's name : Colin McCrawl

The cage looks very sturdy but makes any 'open' airflow, very dirty. Still recommend a clean 'closed' sedan.

If they're allowed to keep non-safety glass installed.

If the glass has to get out, cover as much as possible of the inside of the car @ the lower roofline level with more sheets of coroplast to keep air from rushing in & down, with the shell acting as a parachute.

A large front dam is a good start.

Sideskirts, wheelfairings - essentially put on all the el cheapo aeromods !

[Vanquizor]

Originally Posted by botsapper

...nice and simple fab solution (trim w/ 'flower' edging). If you got extra alu, make rear wheel well covers (made removeable w/ Rivscrew speed fasteners). Now, if you got plenty, form yourself a cool (w/ lexan rear window panel) fastback !!!

Not sold on the wheel covers... our 4 tire change was under a minute last time we practiced, it would be tough to convince me the aero gained would make up for the time it took to peel off the covers and re-install them.

I've been eyeballing the back of the car, and I wonder what gains there would be going to a fastback. I thought I read somewhere that if you end up with an angle between 15 and 30 degrees it was worse for drag then cutting a steeper angle and letting the air seperate.

On account of safety concerns from one of our team members the roof is staying on and we'll put lexan in where the glass we need to remove was.

[dennyt]

Originally Posted by Vanquizor

I've been eyeballing the back of the car, and I wonder what gains there would be going to a fastback. I thought I read somewhere that if you end up with an angle between 15 and 30 degrees it was worse for drag then cutting a steeper angle and letting the air seperate.

Some relevant images from an aerodynamics book that Piwoslaw scanned:

[euromodder]

Originally Posted by Vanquizor

Not sold on the wheel covers... our 4 tire change was under a minute last time we practiced, it would be tough to convince me the aero gained would make up for the time it took to peel off the covers and re-install them.

You could make some holes in the wheelhubs where the bolts are.
A hinge could make the wheelskirt swing aside / up.

I've been eyeballing the back of the car, and I wonder what gains there would be going to a fastback. I thought I read somewhere that if you end up with an angle between 15 and 30 degrees it was worse for drag then cutting a steeper angle and letting the air seperate.

Yes, drag increases as the angle of the rear window increases, then drops again when the angle is steep enough (hence the Kammback).



You'll find more aerodynamic illustrations here :
Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - Piwoslaw's Album: Aero drawings

[botsapper]

Thanks Euromodder,

Recommended aero templates and fastback angles will come out from many people...

Magical numbers of 10-12 degrees.

Here are just visual concepts. (quick tire change time is valid, could use quick release 1/4 turn camlocks or just delete)

Conceptually, there are rear vertical fences that holds the new lexan rear window/fastback at the best low drag angle. Ideally a true tapered boattail is the best but this might be the easiest to fabricate & even easier to test & adjust the back angles. You could also adjust trim edges depending on your track venue.

Other aero masters could chime in...