The Daq Civic aero project continues . . . slowly

[k.civic.f4i]

what did you use as mounting points? i see you used zipties. where did u attach them though? in the front to be specific

this is all i have aero-wise
http://i183.photobucket.com/albums/x97/imokrs/2.jpg
flush
http://i183.photobucket.com/albums/x97/imokrs/1.jpg

[daqcivic]

The front edge of the undertray is attached with screws to the front bumper. There are also several places where it's screwed into the factory belly pan to keep it from sagging. I don't remember exactly where all the zipties are attached. I had to get creative as I didn't want to drill any holes. Basically I found holes in the chassis wherever I could and looped the zipties through them. Between the axles most of the support for the undertray comes from having the outer edge stuffed under the plastic rocker panel covers.

BTW, I updated the first post to include newer pics.

[Jyden]

Some nice moods, a good inspiration for me - thanks for posting all those pictures

[daqcivic]

So I finished my new front deflector design and took a few pics. I didn't get a good reading on my last HWY trip so I don't know if they measurably improved FE, but I've finally got the design right I think, as far as theory goes.

From the front:


From the angle at which I imagine the airflow will approach the deflectors (notice the inner side strakes bordering the wheel wells):


From the side:


Another angle:


This shows the little center section of the front undertray I covered up, and further back, the center engine bay vent which I removed the lip from:


Next up for mods are a smaller engine bay vent, revised grill block flush with the bumper, revised rear suspension arm covers, revised rear tire deflectors, revised mirror mod, and a trunk lid extension.

[123456]

i would definitely say look into vacuum forming, your deflector prototype looks great! if you vacuum formed some abs plastic to those contours it would be impeccably smooth

[Cd]

Very very nice !

The angle in the first picture seems to show a large area of the tire that is still exposed to oncoming air. Is this just because of the angle of the camera when you took the shot ?

[Cd]

One other thing that I wanted to mention was that I noticed that you were trying some aero mods with the mirrors.
You are of course aware that our mirrors fold back right ?

[daqcivic]

Yes, you're right, from directly in front the outer portion of the tire is exposed. That's intentional, and in line with what you see on OE deflectors. The underbody, especially the front, is a high-pressure zone, so that as air approaches it will want to escape out the sides, hence the direction of the airflow coming at the front tires is more like what you see in the second picture. Deflectors that extended to the outer edge of the tire profile would be diverting air further out than necessary, effectively increasing the frontal area of the car as a whole.

On production cars with deflectors you see a variation in how far to the sides the deflectors extend. This is almost certainly because every car will be different as far as the precise direction and pressure of the airflow as it approaches the front tires. It's pretty hard to tell w/o a windtunnel, though tuft testing might reveal something, but in my estimation my car will create more than average pressure in the front underbody, and therefore a greater angle at which air comes at the tires (say 35-40˚). My reason for suspecting this is that the lower edge of the bumper is quite high in comparison to the ground clearance, so the angle of my front undertray is quite steep. I wish there was an easy way to remedy this, but it would be challenging and impractical for a number of reasons, not least of which is the steep approach to many of the driveways I frequently use and my soft suspension--I need that ground clearance.

[daqcivic]

On the mirrors, yes, I know they fold back. I'm not sure it would help reduce drag. Yes, it reduces front area, but it might cause even more flow separation along the sides of the body. You'll see mirrors on newer (especially high-priced) cars that have a larger gap between the car body and the mirror housing, as well as a smaller mounting arm, I think because it disrupts flow along the length of the car less. Ideally, mirror housings would be as small and slippery as possible and mounted at least several inches from the car.

Now that I think of it, perhaps I should try some sort of extender, barring replacing the mirror with something a lot smaller.

[Cd]

I tufted my car with the mirror folded back. It seemed to help, but you can still see some effects from the mirror on the sides of the window.