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First aero-mod: front air dam
I decided that this was the easiest and cheapest thing I could do to start with on my beat-up old Sentra. I measured the clearance from the bottom of the plastic bumper shroud at about 8 inches, so I figured a 5 inch dam would go about 3 inches above the road. The length was 80 inches.
I had a sheet of sign plastic- Trovicel, I think it's called. It's easy to work with, but more brittle than ABS or Coroplast. I decided to wrap the plastic with aluminum flashing, to strengthen it and prevent chunks being knocked out by road collisions.
The flashing just happened to be 10 inches wide, which I took to be an omen, considering that I had already cut the plastic to five inches. I folded the aluminum down the middle, sprayed a coat of Scotch brand adhesive in it, and laminated the whole sandwich. A coat of flat black to make it less visible, and then the mountng hardware.
This hardware consists of 1 inch steel L brackets, sandwiched on the dam with a fender washer on the far side to spread stresses out a bit. Self tapping screws driven up into the bottom lip of the plastic bumper finished it off. It feels sturdy, and handled today's road trip with no apparent problems.
The aero advantage is a gain of about 5 mpg, from 42 to 47 for this trip. I drove through very strong crosswinds, about 30-45 mph directly across the roadway for the last 150 miles of the 360 mile trip. I hope to get a better idea of how it affects mileage over the course of a few hopefully calm days of driving.
Total cost- (I had everything but the mounting hardware in my shop)= $10
Money saved so far- about $3.65 (Figuring the difference at about 0.91 gallons for this trip at $4.00 per gallon) A couple more trips and it will be paid for...
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