My mpg increased from about 20mpg to about 23.5mpg from the El Paso to Phoenix run. Had a small minor problem with the ignition (one wire popped off the standoff and was grounding out on the EGR valve) fer the first 100 miles out. Refueled shortly there after, reset my trip meter and went on my way. I think some of the increase was from driving during the day (I drive mostly at night). I've had to pull the extended air dam off since I'm coming across more dips/bumps in the road while I'm in the LA area. I'm thinking of putting on some front blocks instead to minimize the frontal area on my run up north. Will update more as I git more data.
Since I got a newer T-100...I just had to transfer the extended air dam setup to it and make it better...
Dropped it down 6.5" from the stock bumper, beefed up the extended supports with some 1/2" Sch 40 pipe, pushed the bottom lip out about 3.5", looking to make a partial front pan from the lip to the engine support beam. Pushing the bottom lip out should make it more rounded like the modern truck air dams instead of the flat wall that it originally was.
Finally got my air dam pan brace and panel in place...
Took it out fer a quick 60 mile trip...not too bad. Not sure I can tell a difference. Scangauge II registered a little better...but not ready to call it a success yet. The air dam pan is held in place by 4 screws to the body. The rest of the screws are to hold the coroplast to the brace. Temps didn't increase or go down. Still have to enclose the front slot so my air intake can use that air efficiently.
Hood and grill gaps taped. Middle grill block in place. Ended up pulling the middle grill block because the mechanical fan was coming on from the higher under the hood temps. Got a high of of 23.45mpg at 60mph loaded with 300lbs of gear.
Added in a meat thermometer to measure the under hood temps with and without the grill blocks in place. Temps didn't change at all with the middle grill block in...so ithe middle block is going to stay fer now. I've changed out the zip tie fasteners with velcro wraps now. Makes it easier to change out as needed.
Added in some side skirts made from some R-Matte along with a belly pan made from a 4'x8' luan panel. The engine bay between the front air dam belly pan and the front cross member is enclosed with some R-Matte as well. That stuff is so easy to work with. Don't have to worry about too much damage if I have an accident as that stuff is just aluminum foil covered foam panel and will disintegrate on impact.
My under hood temps have topped out around 140?F...just sitting still. Thinking about enclosing the battery in R-Matte and venting some air into that enclosure from the front to keep the heat from affecting the battery life down the road.
Just got my best MPG (23.7mpg) on the last tank...driving at 70mph!