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

[chumly]

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 but I'm not done testing. Chumly

[CitroX]

Good looking mods 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.

[euromodder]

Originally Posted by CitroX

Good looking mods 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.

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

[CitroX]

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.

[NeilBlanchard]

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

[CitroX]

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%.

[geo1991]

Great inventive use of materials.

[ECONORAM]

Originally Posted by chumly

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! Chumly

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?

Originally Posted by ausias

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

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

[ECONORAM]

Originally Posted by CitroX

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.

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....

[CitroX]

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.