Any ideas for an airdam? - Fuel Economy, Hypermiling, EcoModding News and Forum

fairdinkumfrankies · 07-27-2009, 12:14 AM

What would be an example of a good airdam for a Geo Prizm? The lower engine bay has a sort of fairing but the car is dirty underneath. Would adding a 1" or 2" airdam make a difference?

IsaacCarlson · 07-27-2009, 12:31 AM

they reduce the amount of air going under your car (which is a 'dirty' place) but I also think they create a higher pressure in front of the lower bumper. What if we made V-shaped air dams. they would have a point at the very front edge of the bumper and wedge off to either side and stop at the outside edge of the wheels. it might be better or it may have more drag than regular air dam because of friction with the iar rubbing on it. i don't know, just a thought. let me know what you think.

cfg83 · 07-27-2009, 01:33 AM

IsaacCarlson -

Quote:

Originally Posted by IsaacCarlson

they reduce the amount of air going under your car (which is a 'dirty' place) but I also think they create a higher pressure in front of the lower bumper. What if we made V-shaped air dams. they would have a point at the very front edge of the bumper and wedge off to either side and stop at the outside edge of the wheels. it might be better or it may have more drag than regular air dam because of friction with the iar rubbing on it. i don't know, just a thought. let me know what you think.

+1 idea. I don't know if it will work, but I'd like to hear what the aero-experts have to say.

CarloSW2

fairdinkumfrankies · 07-27-2009, 01:36 AM

I was hoping to do something to improve the air flow. I know that if I lowered the car I could reduce some of the air flow and improve my cd/reduce drag. I would be guessing as to whether the "V" would be better. My thought was to add 1-2" of rubber or plastic to the chin of the bumper which would simulate lowering the car with a $400 suspension kit. The frontal area would increase slightly but the dirty underside would gain from the reduced air flow. Side skirts at 1-2" would be planned also. I don't have the time or tools required to do a belly pan which sounds like it would be best.

Tygen1 · 07-28-2009, 12:42 PM

A fairly popluar method is the to use some Garden Edging from Home Depot. $12 buys enough for two cars and it is extremely durable. I used it on my car. Did the HD lip, mud flap removal and grill block and it was all good for around 3mpg. Because the HD stuff is so cheap, it make for easy expirementation. If it doesn't work, then your out $12 and you can make it happen tonight, vs. waiting and planning and dreaming...

wagonman76 · 07-28-2009, 12:54 PM

I agree on the lawn edging. I got a bunch of it in roadside piles during spring cleanup (some new stuff too), but $12 still isn't bad. Very durable for when you bottom out on steep driveway transitions or potholes or anything else. Am thinking about replacing the aluminum airdam on the Celebrity with this too.

fairdinkumfrankies · 07-29-2009, 07:37 PM

Wagonman76,

Did you notice an improvement with the airdam?

wagonman76 · 07-30-2009, 12:50 PM

I noticed about a 2 mpg improvement with the Celebrity after adding the airdam, and a similar loss when I took it off for awhile. Hard to say with the wagon, I haven't driven it much since adding the airdam. But since it is almost the same car and both undercarriages are the same (very dirty), I would think it should give a similar improvement with all else equal. I hardly drive it now, but will be driving it full time when winter starts.

outsidethebox · 07-30-2009, 05:58 PM

That's a great idea I was thinking of using some conveyor belt. But I like this a lot better you don't have to trim it, and it's a lot lighter. I am doing the front end and this would work well. That is a very good MPG gain percentage wise. I will build it up before I put it on so it will wrap the front wheels.

instarx · 07-30-2009, 08:51 PM

Go to the Home Depot and by one length of vinyl gutter (the good architectural kind, not the cheaper "U" kind, it's still only about $4). Cut it lengthwise so you are left with an "L" shape. The back part of the gutter becomes the air dam and an inch or so of the bottom of the gutter becomes the forward-facing "L" mounting tab. Use the short L-tab part to attach it to the car with screws, velcro, or rivets. If you make a few straight cuts in the L part in strategic places the airdam part will curve nicely where it needs to (see my pics). The air dam is about two inches deep - just about the perfect height for my car. Any lower and it would be a pain at curbs and entrance dips.

I did this with my Volvo, attached it with industrial velcro and double-sided tape, and it looks great - almost factory. It can be painted if you use a vinyl paint.