[Big Dave]

Re: Post #40

My air dam is 3/8 inch rip-stop belting. You can only get it from industrial rubber supply houses. I'd think in a port area like Sea-Tac somebody is selling this stuff.

My air dam sits 10 inches above grade inboard of the wheels and tapers to 7" above grade in front of the wheels. That's about as low as i could go without dragging hitting parking curbs. This setup works. In A-B-A tests it was good for a 1.0 MPG improvement over no air dam.

The conveyor belt is nearly indestructible. I hit road kill, debris, tire strips, and even wooden boxes - not even a hint of a problem. It bulldozes snow just fine.

Rip-stop does have its downsides. It isn't easy to find even when you know where to source it. It is EXPENSIVE. Figure $75 for enough for a full-sized pickup air dam. It is maddeningly difficult to fabricate if you don't have the tools. If I were doing it again, I'd make a paper pattern and pay the $50/hr shop rate to have it professionally fabricated. Rubber-supply houses have the 15 ton punch and shear presses needed to fab the stuff.

The stuff is fairly heavy and you'll have to modify your bumper to hold it.

I tried making the air dam to one and a half inches above grade. that only yielded another 0.25 MPG. Going lower increases net frontal area. It dragged every time I hit the brakes. The dragging didn't hurt the air dam but drove me crazy.

I also tried a pair of belting skirts between the wheels but a rail crossing tore one off. I didn't notice anty difference in the short time I had the side skirts.