I added a grill block behind the grill with some coroplast. I cant seem to get photobucket to upload the pictures. Anyway, I managed 13.61 mpg on the last fill up with the grill block/air dam combo. My mpg is a lot more consistent now, my 4 fills with the air dam average to 13.3125 mpg. My average before the air dam was 12.2 mpg. My next aero additions will probably be a small belly pan coming from the bottom of the air dam, and some small fender skirts. Also I think WAI helps on this truck so I might add some ducting when I install my new shorty headers. A 1.1 mpg gain isn't what I was hoping for, but its the best consistent gain I've ever had on this truck.. and ill take it.
It does seem to be helping the air dam. My last tank almost hit 15 mpg, but I also ran the gas gauge a little past "E" more than i usually do. So Ill have to see how the next tank turns out. I also had to open up a bit more than what the pics show to keep it from getting hot.
That's true, and it is the most consistent gain I've had so far. Now I just wish I wasn't out of town for weeks at a time so I could put finishing touches on it. I will be taking the air damn off for a couple weeks to have an alignment and new tires done. Should be interesting to see if mpg goes back down.