Air dam shapes vs air dam delete
 

seeing more and more cars with air dams positioned well behind the front of the bumper almost in line with the front wheels. is there any research about different designs? u can see in pic belowAttachment 16846

below is my car with current air dam
[ATTACH]Attachment 16848[/ATTACH]

option 1Attachment 16849
option 2Attachment 16850
option 3Attachment 16851
I like option 1 and option 3

however with hatch backs space in the car needs to be utilised so more often than not you and up with a very flat bottom with no real air pockets or gaps. im considering deleting the air dam entirely and just improve the airflow under the car. I have seen posts where air dams were removed in favour of flat under trays but no results of that change?

Cant hurt to test the difference between a belly pan and air dam. When you go belly pan, you will still want to use tire spats to block the air hitting the tires. Harder core still would be tire boat tails front and rear (look up Arcosine's Saturn project for what I'm poorly describing).

I think OEM is using recessed air dams for multiple reasons. It's more hidden so it doesn't affect the looks of the car as much. Closer to the tires means you can go lower without scraping and it is less likely to get stuck on parking blocks. Also, some cars are set up as "bottom breathers" where the dam is actually integral to the cooling systems (C5 Corvette) and needs to be placed directly under the radiator.

Airdams need to be as far forward as possible. Sometimes removing them can reduce drag, but if the front goes light at 80 MPH, then you're endangering the people in the other cars around yours.

I think an air dam of a given height works better at the front edge, than set back, because they have a stronger affect on the stagnation point, keeping more air out from under the car. I think the air dams set back more (but not bottom breathers) are like that because manufacturers are tring to protect them. My front overhang is longer than most newer cars, but the 2" air dam I added out at the front edge would be long gone by now if it wasn't made out of paver edging, which is stronger than the bumper material, and held on by about 15 1/4" bolts.