Yet another lawn edging air dam and a question regarding rear diffuser
 

Here are pictures of my new air dam.



This was made from a 3/4 inch box aluminum tube (14 gauge) bent into the shape shown. Once bent, I riveted lawn edging along the aluminum every 3 inches or so. It is screwed to the car with four screws untilizing stock holes that would normally attach the plastic belly pan to the fiber pan around 12 inches in from the nose.



It took about 2 hours to complete. This was amazing time considering it was 6 degrees F when I started and I did all the work outside. I had to stop repeatedly to warm my hands and warm the lawn edging at my heater.



The whole dam weighs very little. If I had to guess, I would say it is about 3 pounds or less.



I have not done any ABA testing. However, here is what I did for the few minutes of time I had;



I took my average mileage from yesterday (a full day of driving without the air dam), and compared it to a drive today around my area with the dam installed. Yesterday was 18 degrees and I averaged 47.1mpg. In 10 miles of driving today (after I warmed the car up), I averaged 49.3mpg. Now, bear in mind, yesterday's mileage was total mileage including the terrible MPG encountered with warm up. While todays mileage was recorded after the car was warmed up. Yesterday I drove 120 miles. So, the warm up MPG would have averaged in pretty well over those long miles. However, I would assume that I could have had maybe .5 to 1mpg better if I had warmed the car up yesterday before I reset the mileage trip odometer. So, realistically, the dam is probably giving me 1 to 1.5mpg increase (conservatively).



I will do some ABA testing sometime soon and report back. :)

The next mod I plan on doing is a rear diffuser. The rear of my car is totally open and really terrible from an aero perspective. So, I plan to make a light weight aluminum frame supporting light (maybe Coroplast) panels forming a diffuser.

Now, my question, since adding the air dam, I am limiting the amount of airflow under the car. I would assume this will minimize the affect of the diffuser. Is that correct? What I mean is, would the diffuser would do more with more air flow under the car? Since I am not after downforce, but reduced drag. Anyway, what are your thoughts?



Matt

Nice work. Look forward to more. It is possible you'll find the airdam too easily flexes at speed, or that it is too close to the wheels to be optimal. I never see these set to far back, they're always at or near the front bumper lip. Any ABA testing you can eventually manage would be useful... and if you chose to move it I think your build allows relatively easy repositioning.

I agree it may flex at highway speed. Not until summer, though. This stuff is rigid in this cold weather. Also, being slightly curved should help its strength. I do not mind reinforcing it, though.

Yes it is very easy to move. I used factory mount holes.

I have seen a number of them mounted back like this. The Volt is a couple inches further forward and my 93 saturn factory dam was nearly the same location. That being said, I only mounted it there because there were easy to access holes right there. :)

I originally wanted it at the very nose of the car. It would have taken a huge amount of work to make it look decent, though. I would have hit nearly everything too.

I am open to doing something different, though.

I cannot wait to do some ABA testing. The weather just does not permit it, though. It goes from 15 degrees and sunny to 25 degrees and windy within an hour this time of year.

Matt

Nice work, had a similar setup mounted to a home-made auxiliary bumper on my Civic for a while, but it got damaged going over a snowbank the separated my driveway from the road. Gotta avoid those road hazards! ;-)

I know there is a difference in every car. However, how important do you think it is that the dam be near the nose versus under the car as mine is?

Matt

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Nice work.
I was under my 09 MKZ last week trying to figure out how I could attach an air dam,
I see your car has the flat panels underneath which makes it a little more difficult.
I would have to build an attachment frame like you did, though I'm not so sure it would
last through the winter here in northern Ohio, have to be pretty beefy to plow
the snow. Think I'll wait till spring.

Corvettes have their air dam right in front of your tires. Even if it isn't the optimum location for aerodynamics, its a good compromise between aero and rubbing on everything.

My Fiat also has it's factory airdam just in front of the wheels. I'm not really sure it matters for aero as the idea is to deflect air away from the dirty stuff, which seems to happen whether it's mounted to the lip or further back. Mounting further back is a more practial solution as it shouldn't require any drilling. If you get 90% of the benefit and the car looks (and can be returned to) stock I'd call it a win.

Thanks for the input. I am open to moving it forward. But this was so easy and if it works relatively well, I am good with it.

Now onto the diffuser and Kammback... :)

Matt