Ideas on improving Festiva aerodynamics

[Safety Guy]

Thanks for the article, Deems.

From the article:

To improve Cd, designers may make the following changes:

1. Round the edges of the front end
2. Tune the grille and fascia openings
3. Tune the wheel openings
4. Place spats (small spoilers) in front of the tires to reduce turbulence
5. Tune the size and shape of the outside mirrors and their attachment arms
6. Reshape the water channel on the A-pillars
7. Adjust the front fascia and air dam to reduce drag under the vehicle
8. Add side skirts
9. Tune the deck height, length and edge radius
10. Install a rear spoiler
11. Adjust the angle of the rear window
12. Tuck up the exhaust system
13. Use a diffuser to tune air coming off the underside
14. Install "belly pans," underbody panels that cover components and smooth airflow

Here are the main things I will do:

2. Tune grille and front fascia openings
7. Adjust front fascia and air dam to reduce underbody drag
10. Install the rear spoiler

Here's what I will consider doing:

4. Spats in front of tires to smooth air flow
8. Side skirts
14. Maybe some partial belly pans

One interesting thing in the article mentioned the vortex generators used on the Mitsu Lancer Evo MR. However, the Festiva hatch drops off much more sharply than the Lancer's so the stock rear spoiler may be a better choice--to abruptly cut off the boundary layer at the roof end.

Anyone with an Aspire might want to consider the vortex generators, however. They are supposed to keep the boundary layer adhering to the roofline/hatchback. The Aspire's hatchback angle seems similar to the Lancer's. There is the question of how much good vortex generators would do on a car spending most of its life under 70mph, however.

Here's a page describing them for airplanes:

http://microaero.com/pages/v_howvgswrk.html

They are supposed to give small planes greater STOL capability, which would probably be at open highway speeds (60mph and up).

My main plan will be:

A. lowering the car about an inch and crafting a lightweight air dam that does a really good job of cutting off airflow underneath the car. It will probably have a rubber bottom skirt to help prevent curb ouchies.

B. Modifying the grille, possibly covering it totally. I may extend it slightly forward over the bumper to see if I can smooth the airflow over the hood.

C. Investigating whether or not the factory rear spoiler does anything.

Wheels and tires will probably be 195/45-14s on 14 X 6" wheels. I may try to work with the wheel wells to see if "spats" will help.

Anyone ever read any articles on homemade anemometers for coastdown measurements?

Karl

[4cylDreadnaught]

mmm... think I might try mvg's


placed where? edge of hood and/or edge of the roof?

[EVOGUN]

Teflon paint!

Thanks :wink:

[Taylor_cook]

i hate bird crap, why do they always poo on my car and not my neighbors? our driveways are under the same tree!

[FestYboy]

go with the flat floor pan!!!! yes it will increase weight but the reduction in drag will more than make up for that and you can reduce weight elsewhere ABOVE the roll center and CG where it's more important. the stock spoiler works the way it's supposed to but it's added weight above the CG. also I'd stay away from the FMS hood and look into a stock fiberglass replacement as the FMS hood adds a second low pressure area to the front of the car. block off any area that isn't directly in front of the radiator. the worst offender for our little cars is that HUGE low pressure area in front of the wipers, it's got to go. my solution: chop the top and lay the windshield back, easy peasy :wink: Drag is what makes the Festy slow, not so much the weight.

if you can do some of these things, you'll probably see a good increase in highway MPG.

[4cylDreadnaught]

the worst offender for our little cars is that HUGE low pressure area in front of the wipers, it's got to go. my solution: chop the top and lay the windshield back, easy peasy :wink: Drag is what makes the Festy slow, not so much the weight.

if you can do some of these things, you'll probably see a good increase in highway MPG.

what if I stuck MVG's towards the back of the hood? Anyone have an accurate map of the boundary layer for a Fes?