Front Air Dam ABA test results: 7.49% increase in MPG at 60 mph (2003 Honda Civic DX)

[Otto]

Originally Posted by MADMAC

Got a question. I have a 2012 Chevy sonic turbo sedan. I was wondering if a air dam is better to have than full under body panels? I'm thinking underbody based off of knowledge I have gathered from this site and others. Could some confirm this for me?

Belly pan is most critical under the nose, then under the trunk, with the mid-section least critical, per Hucho. It's reportedly a fair amount of work.

Reportedly, you get more bang for the buck with an air dam under the front bumper. It's comparatively cheap and easy to install, i.e., a few bucks at Ace Hardware or Home Depot for a roll of garden edging, which would do two or three cars. In absolute terms, the air dam may not be quite as good as a full belly pan, but the difference in aerodynamic efficiency is marginal vs. cost and work involved. And, the air dam deflects air smoothly past the front wheels, which are effectively buckets of drag, given the oblique angle of airflow hitting them. (Previously on this website is a revealing wind tunnel picture from Hucho's book, where an Opel Calibra has the front wheels impacted by airflow at an angle of about 60 degrees:

http://www.google.com/imgres?hl=en&b...7&tx=132&ty=95

Anyhow, given such flow around the nose of an unfaired vehicle, the air dam seems a cheap and effective way to shunt a lot of draggy air past the wheels, and keep it from building up under the draggy underbody of the vehicle.

It might be even better to combine air dam and undertray, and/or fairings in front of and behind each wheel, per Prius et al.

[Xist]

Originally Posted by MADMAC

Got a question. I have a 2012 Chevy sonic turbo sedan. I was wondering if a air dam is better to have than full under body panels? I'm thinking underbody based off of knowledge I have gathered from this site and others. Could some confirm this for me?

Sporty Modder described it well in http://ecomodder.com/forum/showthrea...tml#post393469

Also consider a airdam, 10% of the work of a full belly and 75% of the returns.

[MADMAC]

Thank you for the info. I'll be looking into the sporty mods form.

[Sporty Modder]

In my experiance, 6+ cars with airdams, I have gained 5%-15%. Worst is my b4000 1mpg for a 19mpg truck, best was my previous Lincoln Town Car, 3+ mpg on a 23 mpg car.
My Celica is avg with about 8%, 2mpg with a 26 mpg car. it is going to get a front belly/splitter and a better designed airdam.
Let me know if you have any questions about airdams.
http://ecomodder.com/forum/showthrea...gts-21369.html

[whatmaycome14]

Originally Posted by Xist

Yes, but will you do A-B-A with the belly pan?

I do not think that any of us will blame you if you forgo it.

Yeah, probably not! Wouldn't that be something though...

[MADMAC]

I wouldn't mind spending a little extra time and money for better results. Car currently just got 57 mpg going from Houston to San Marcos averaging 60 mph. Cars current mods are lowering springs (two inch drop), put mesh behind the grill to help protect from rocks and decrease some air going into the engine bay. So if I was to only see a 5% increase from a underbelly that would actually be very nice.

[Sean.Heihn]

I wonder how low is too low? I just put on a landscape edging air dam, and since my car is so low already, it's about 1~2" off the ground.

[MADMAC]

That's my problem. The stock air dam on my car won't even allow me to drive over a shoe.

[Sporty Modder]

Originally Posted by Sean.Heihn

I wonder how low is too low? I just put on a landscape edging air dam, and since my car is so low already, it's about 1~2" off the ground.

The one on my town car was about 3" off the ground, It would scrape the ground when I would brake, and when I travelled in the lanes with deep tire grooves.

Hot rod says scrape the ground, i think it was bamzippow did that with belting on his truck.

[whatmaycome14]

I've actually decided that scraping isn't really a bad thing (at least with garden edging). It hasn't been damaging my mounting points and thus far it looks like nothing bad has happened as a result. So... who cares, right?