Dam, It works! (Air dam on Smart Fortwo: 3-4% MPG improvement)
 

I just made an air dam out of some lawn edging. A B A testing shows 3.16%-4.2 % (avg 3.73%) better mileage. It took a whole half hour to make and install it, I should have done this a long time ago! :D Chumly
http://i.imgur.com/DLyhmKG.jpg

Good job! :thumbup:

Thanks for posting!

What speed did you test at?

Do you have a picture showing the whole front of the car?

I was anticipating test results and procedures...please?

I drove the car about 20 miles before any testing so it was completely warmed up. A is with the dam and B is without. I reset the scangage at a set point after getting up to speed and set the cruise control at 60 to be consistent, drove 5 miles one way, turned around in a parking lot and returned to set point on all three runs. Temps were the same on all three runs with a stop of maybe 5 min. between runs to take off dam and to reinstall it. On the last run I actually had to pass a car but I didn't need to touch the throttle, I don't think it should have made much difference. A=46.1 mpg, B=44.2 mpg and A=45.6 mpg. Chumly

How did you mount the edging to your bumper? We would love to see more pictures of the installation!

I'd like to put this on the front page, if you like. Please post another pic or two showing the whole front of the car.

Thanks! The black pizza pans look good, too!

Attachment 13158

Attachment 13159 More pics

I just screwed it to the front valence with some panhead screws and put a thick wire through the tube in the edging to stiffen it up.

Sure , go ahead. I'm still computer illiterate (according to my wife and kids).

did you use lexan for the grill block? yours is much better looking than my white coroplast one on my red truck... havent gotten to painting it yet.

Tis inspirational, I feel like sticking one on "Boxy" But what could I make it out of other than Coroplast?

the air dam? or the grill block?

for the air dam I believe most people use the lawn edging, right?

I have heard that for air dams some people use conveyor belt material, due to its durability.

Yes conveyor belt would work well the stuff isn't very light FYI and its not cheap to buy new.. But if you can find someone with used stuff that would work I haven't used it for this but I might seeing as I could get it for free from a friends construction out fit.

One day I was in my garage and noticed the old bug shield I found months ago and decided to try it because it looked like it would work if I trimmed it and it did.I think it's made of plexiglas but if was to buy the material I think I would use Lexan ,it's less brittle. I wanted to still use my foglights if necessary and so far no problems. Chumly

maybe 1/8" thick polycarbonate for your grill block? Flexible enough, pretty indestrucable and virtually scratch proof. That way you can get a pretty fluid fit and finish against the body as well.

If you have any edging left over, make some rocker skirts for your fortwo.

Anything that can get the mileage up on those is a good thing. Seeing an EPA rating of just 38 blew my mind, I thought, "surely these little things can do better? On premium, no less?"

I installed a lawn edging air dam a few weeks ago as well as partial rear underbody panels to reduce the drag from the rear bumper and I have seen gains of about 2+ mpg on the highway. The lawn edging is very resillient. I accidentally left my car in neutral and walked away, it rolled forward and absolutely smushed the air dam on the curb. Backed the car up and the air dam popped right back into place.

I've got some pictures on my build thread. Like OP said, this should have been done a year ago; it was that easy.

When I bought the car EPA said 33 city and 41 highway. My 1st tank was 43 mpg. I've already gotten over 78mpg on flat ground with no wind for a couple miles . The smart does much better at 50 vs 60 mph, it seems to lose about 1 mpg per every mph above 50. I'm willing to try anything as long as it doesn't cost too much. I live in a rural area so the traffic is usually light which helps a lot. Chumly

Chumly, has anyone put a Kammback or boat tail on a Fortwo, that you know of?

Whoops! My bad
 

I misremembered; the 38 is actually in reference to the Ford Fiesta I was writing about as an alternative to the fortwo in a blog post. Yes, 41.

Still requires premium, though.

the airdam is a very good invention. IT works very good in my car. But I'm using a 45º airdam.

Not that I know of but it shouldn't be too hard to do on the coupe but I have the cabrio, it's not that I didn't think about it. I already have some vg's on the spoiler, if nothing else they help in handling on the rare times I drive faster than normal. Chumly

I think that with how short a smart is, a boat tail could net you some great gains without sacrificing drivability and parking. The extra acceleration and higher top speed doesn't hurt either. :)

:D

http://ecomodder.com/blog/wp-content...5/smartera.jpg

From: http://ecomodder.com/forum/showthrea...aybe-8293.html

(More "practical" examples of aero Smarts in that thread.)

I was referring to the air dam. I'm seriously considering putting one on the ol' "Box", Though I don't have tank-to-tank date for the car yet.

I took inspiration from this thread and made an air dam for my Jeep over the weekend. I'm planning on making one for our Sentra once my wife returns back from a trip with the car.

Pics forthcoming.

I finally got around to making the side skirts out of a vinyl gutter, it took less than an hour to do (minus paint drying time), 1 vinyl gutter, 1 can of spray paint and 12 screws. I'm still testing and it looks very promising, more stable in wind and mileage seems to improve but the weather hasn't cooperated lately (colder). I'm still getting better mileage in cold weather than I did before installation:D but I'm not done testing. Chumly

Good looking mods :thumbup: I tried an air dam - splitter. It did harm for my mpg. Maybe it was the splitter bit. However I have a full belly pan and a boat tail. So it might be that air underneath the car does not do that much damage but the increased frontal area does.

https://fbcdn-sphotos-d-a.akamaihd.n...10116470_n.jpg

Don't drop the air dam lower than your belly pan.

Remove the splitter
It so pronounced (about 5cm , 2" ?) that it causes extra downforce = extra rolling resistance = extra drag

It is long gone. I expected that the results would be negative on the mpg, but this ford rs splitter was lying around so had to try it :). The down force was somewhat noticeable and the car felt more stable though.

Did you try a full upper grill block and a partial lower grill block?

Yes. I've tried a number of combinations (cooling fan is operated by a switch by the way). This engine cools very well even without the fan so i do not need to use it, but blocking too much decreased the mpg dramatically, on some runs I even had as low as 34 (normally getting about 49). So by trial and error I ended up blocking about 50% of the bumper and hud grill. The gains seem to be under 2%.

Great inventive use of materials.

I am curious as to how you fastened your wheel covers on the wheels. Did you bolt them on, with washers holding the bolts in place?

I am not following the 45º air dam idea? Is it angled forwards at 45º to the road surface?

Curious results. I have a home-brew splitter on my truck, and it honestly seems to help. (No formal A-B-A tests, but some back to back drives to work) It protrudes about the same amount (5cm), but is mounted directly under the factory plastic air dam. I did try to extend one down about 2 inches lower before, and that was detrimental. The splitter with a set of belly panels seems to do pretty good...
So I wonder now, if your belly panels had been level with the splitter how things would have tested....

Look a few posts above which explain why the mpg dropped on my car ;). And if the belly would be as low as the splitter the car would be undriveable.