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Planning custom front air dam

10K views 21 replies 7 participants last post by  Jestes 
#1 ·
I've got a 99 SC LB 7.3 4x4 f250. Unloaded and empty hwy cruising I'm getting 18-19MPGs I'm looking to get that up as high as possible. So reading some stickys in this section air getting under the truck creates a bit of drag. I don't know a thing about aerodynamics other than it can make a truck look goofy. So I was thinking about making an air dam that's removable or get real fancy and do retractable with hydraulic arm or just a hinge fold up. I'm thinking maybe two or three inches off the ground and only use it on the highway. Does any body have any suggestions for material? Maybe just thick rubber pad or plastic? Or a steel/aluminum frame wrapped in vinyl.
 
#2 ·
for reference and out of memory

the 08's first came out with a small lower valance
then they went to a massive one and at the same time the MPG was supposed to have gained 1-2 mpg

but I have no clue if there is a limit to how far you can go and still see any benefits

guess a wind tunnel would be the only way to see
 
#3 ·
Lol I have zero access to a wind tunnel. And the price I'd pay to use one would probably out weight any possible savings on MPG I'd get with this truck. Unless I make this and people are like wow that's cool make me one then I start a production plant and do research and buy my own wind tunnel but that won't happen.
 
#5 ·
Or, if you're like most of us, you just enjoy the tinkering aspect and your satisfaction comes from knowing you did it, not from the gained MPG.
 
#7 ·
That's why I'm talking about a hydraulic or something rather. I like making things like that. I mean wouldn't it be cool to hit a button and have a big old valance come down?

BTW what's a zoodad?
 
#8 ·
"cool air" intake mod. Do a quick google and you'll see. No verifiable data that it does anything for your truck other than make it a little more noisy. lol
 
#9 ·
2wd conversion I'd guess, and a gear swap. First option is ridiculous, but the gear swap would help. My regular cab 2wd bone stock gets 19 and change hand calculated, mixed in town driving.
 
#14 ·
I second that. In need my 4x4. Sometimes to get out of the "driveway" in the morning. I use it so often that I rarley unlock my hubs. I don't want to go any lower than the 3.73s they do what I need to when towing, if I wanted an MPG cruiser it definitely wouldnt be what I have. I'd just like to help out what I have. I'm working on a diamond plate aluminum bed cover right now. I'll put a thread up when it's done. I just figured an air dam will help according to one of the stickeys in this section
 
#11 ·
I've had my lifted super dutys, and was ready for something different. Besides, my wife always tells everybody how massive my dong is, so I don't have to lift another truck to prove it! ;)
 
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#13 ·
Didn't Dave have some pics of air dams he's tried? Nothing fancy but effective and give you ideas... Used conveyor belt material I believe and had an optimal distance from the ground that was effective and didn't get ripped off at every dip in the road...
 
#15 ·
I saw some of his posts.. But can't find any pics
 
#16 ·
Search this forum for "dam", or go to one of Dave's posts, click on "member's galleries". Lots of pics on page 3.

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#17 ·
Re: Post #16

This is indeed a picture of my first effort at an air dam. It may be aethetically egregious but it was within my limited bodywork capabilities.

The material is 3/8" ripstop conveyor belt. This version clears grade by 1.5 inches.

I have stayed with the same material. It is virtually indestructible. No road debris, snow or ice fazes it. A little brake fluid and it turns coal black and looks good as it ever did (such as it is).

An inch and a half was too close to the road. it dragged every time I hit the brakes. After much experimentation, I found the best height was 7 inches above grade in front of the wheels and 10 inches above grade in the center. This clears all parking curbs. Make sure the air dam "covers" all the steering rods.


The material ain't cheap. In the picture you are looking at $75 worth of rubber. Forget the cost and embrace the value. Barring some stupid driving, it will probably outlast much of the truck.

Word of advice about this material. It is a 24 karat bear to fabricate. Being indestructible comes at a price. If I were doing it again, I'd make a paper template and pay the conveyor belt shop's rate and have them cut it to shape and punch the holes. Punching a hole requires a 15 ton press.


The original (1.5 inches above grade) gained me 3.5 MPG versus no air dam. The more practical 10"/7" dam gains me 2 MPG versus no air dam. I drive 25,000-35,000 miles a year so anything that gets me 2 MPG pays for itself quickly.

Surely, somebody in the Nation can make an air dam that looks better than this.
 
#20 ·
Dave, this is some great advice thanks a ton. I think I will make a cardboard mockup. And if 1.5" from the ground gave you 3.5 mpg, that's awesome. I'm going to try making it easily removable for just highway use so it can be maybe 2 or 3" from the ground. Or if its flexible enough, attach a magnet to the bottom so it can fold up and stick up somewhere out of the way.
Couldn't the holes be drilled instead of punched?
 
#18 ·
Dave, I always wondered at what speed it would fold back under the bumper. Or have you just never gone fast enough to experience it?
 
#19 ·
I have a couple of metal stiffening plates in front of the wheel where the dam gets with 7" of grade. The stiffeners go 12" above grade.

At 90 MPH it pretty much holds its shape.

I left it on last winter and even bulldozing snow, it more or less held its shape.


I'm sure somebody more talented can make it look better, but functionally it is nearly optimal.
 
#22 ·
[QUOTE=Dave Whitmer;4well the conveyor belt stuff sounds like my material then. Now I just have to find it in st Louis area.
 
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