Belly pan for trucks
 

How do you deal with air flow under a truck? No matter how you smooth the air out from the front to the rear axle you still have the rear axle in the way. Do you deflect air out from under the truck with trailer skirts?

Truck underbelly
 

First you turn the truck over........:D:D:D:D:D

With a solid rear axle, I would build the underbelly rearward to the axle, leave space for the suspension travel & axle then start behind the axle and continue to the bumper.
That's my starting point and I'm stickin' to it. :):)

I just got mine done today...

My belly pan thread over at ToyotaNation.com... ;)

I lowered my belly pan about 4½" below the frame so it's pretty close to the bottom of the rear differential.

This is what it looks like from the front going to the back... :D
http://i164.photobucket.com/albums/u...0/IMG_7507.jpg

From the back going to the front...
http://i164.photobucket.com/albums/u...0/IMG_7524.jpg

I just got my second best ever gas mileage with a 26.58 mpg at 65mph. Previous run last year fer the same time period and same drive was 20.49 at 70mph. :D

looks pretty good bamzipow, but might I make a suggestion and overlap the panels from the rear to the front so there is no chance of an edge flapping and parachuting.

They actually butt up against each other and I've taped some seams down. Thanks fer the suggestion. ;)

The engine bay panel still needs to be revamped since I put in the cross members. It's short about 2½"... :(

at least you have a bellypan, Im still trying to find materials to make one for my ranger, along with how Im going to go about it in the first place.
unfortunately, there wasnt many (if any) coroplast signs around me during the elections, so I could grab any up. but even then, Im not real comfortable using that type of material, so I think Im just going to stick with my original plan of using lightweight aluminum.

I initially used 1x2 wood and luan to build a test belly pan before I moved on to my current choice of materials. I wanted to learn what was going to be my best method to approach my goals fer my belly pan. One of them was fer minimal fasteners to be removed fer access. Another was adjustability...I can raise or lower the belly pan with some PVC pipe and longer/shorter bolts. :D

I would say give some thoughts to some "test" materials before you move on to sheets of aluminum. You don't want to find out yer design wasn't optimal fer yer material choice... ;)

good point
I think I will see if I can hit a recycle center and see if they have some coro.

That does look great bamzippow, do you have your own thread about building it here?

Not on here yet but I do at ToyotaNation.com and Gassavers.org.

if possible, Id be interested in seeing a post with all your mods, Im looking at your profile avatar and am interested to see that front air dam and how you connected it all.

My belly pan build... ;)
My modified air dam build... ;)

awesome, thanks for the links !

reading through your worklog on the air dam, I wonder why you didnt just make the entire thing a continual smooth front section ?
that center area is a bad catchall for air, if smoothed out Im betting you would net a decent percentage gain in mpg. unless there is a reason for it that Im not understanding of ?

liking the bellypan, I really need to get to building one myself, but of course life has something else in mind for me, such as both my son and I being very sick at the moment... just in time to force me to not be able to drive down and spend thanksgiving with my mother and the rest of my family... :(

This user did a complete smooth pan but I really wanted to reuse the old air dam as much as possible. At the time, I didn't want to invest a whole lot of money into the project as this was one of my first attempts at a new/different air dam. Also, I installed a transmission cooler that I wanted to git air to and a completely flat one didn't seem like a good choice at the time. Who knows...I might eventually go in that direction but I'm pretty happy with the abuse my current setup can take. :D

Also...with my current setup, I can experiment with different configurations without a whole lot of new materials or designs. ;)

Sorry to hear about you being sick and not being able to spend time with yer family. Hope you git well soon!! :D

have you considered perforated sheet metal ?

when I do both my grill blocks and my airdam I plan on using perforated aluminum that allows a 38% air to surface. this way I'll still be letting in enough air to keep things cool (I hope) while giving most of the advantages of a full block off.
my truck came stock with a trans cooler, which sits right below the grill opening, so taking that into consideration as well. I posted a mockup of what Im planning on my grill to give you an idea of what it will look like. in this post:
grill mockup

Well...this is what the front of my T-100 looked like before I started. I had just finished polishing my headlights. Yers are in need of some polishing, too! ;)
http://i164.photobucket.com/albums/u...0/IMG_4657.jpg

As you can tell...it's not much of a front end to work with. The frame has some extensions that will always notch out the front air dam if you bump into something...as you can see on the left side of the truck. So my first thought were to drop it down so it wouldn't do that...thus my modified air dam started the whole business of my aerodynamic research on my truck. Also, the filler panels can easily be removed to git access behind them. If it was a solid piece...I'd have to remove the whole air dam just to do some work. :(

I believe my MPG numbers should validate a belly pan fer trucks if yer road use allows you to drop it down some. The big difference was the rear pan/diffuser in the back.

Yer Ford Ranger has more to work with. I would try some sort of inexpensive covering that you can form fit over yer bumper (like aluminum flashing) at first to git a basic form shape and validate some numbers fer you. Start out cheap and then move to the more expensive stuff. Then you can move on to the belly pan... :D

WOW, nice build thread on toyotanation, shame they killed your ecomodder.com link. :thumbup:

Can you explain the reason you skinned the top of the belly pan? Where is that air flowing from?

Sorry for missing it but, what was your before and after MPG for the skirts/belly pan?

I am working on a proposal for my boss, our bricks do ~40K miles a year but need to look "normal" so this may go over better than my Kamm back idea.

My fuel log... ;) I think I was just barely breaking 20mpg before I started the aero mods. The first thing was the air dam and then the belly pan/side skirts. I just started with the rear pan/diffuser this past trip. :D

Reason fer skinning the top of the belly pan was to make sure I had belly pan structural strength and smoother air flow fer between the body and belly pan. I also needed a radiant barrier fer the bottom coroplast skin so skinning the top fit the bill. ;)

The air flow will eventually be tunneled from the front (radiator)/lower grill openings to the rear along the exhaust system. I still have to button up the sides of the frame so the wheels git their own air tunnel.

I might try out a side skirt setup where it's just flush to the bottom of the belly pan. We'll see... ;)

what engine is in your truck ?
Im sort of surprised that my ranger gets better mpg ?
I havent taken the time to do a full figure, but at the moment I just got 280miles from my last tank, all in town driving. I believe I have an 18g tank but not entirely sure (will find out and repost) but 280 miles all in town is my personal best at this time by using hyper-miling techniques.

Im hoping to make a couple of hwy trips here soon to see how far I can push a tank on the hwy, my best so far is 320, Im hoping to be able to reach 350 by just hyper-miling.

My T-100 has a 3.4L V6 engine in it with an automatic transmission. I have a 24 gallon fuel tank. It weighs about 2 tons after I load my gear/tools in the truck.

I can usually git about 300 miles with just in town driving before I see the low fuel light come on. I'll probably unload the back of the truck of my tools and gear to keep the weight down during the winter. ;)

unloading made a HUGE difference for me, I easily gained 20-30 mpt by taking out the random junk that gathered in the back. I actually had 5 large sized boxes of tile that I had forgotten about, that was sitting under a tarp I had thrown in the back without folding. they have probably been in the back for close to 4 mos....

BZP, did you attach the skirts to the body lip or just to the side supports and let it float top and bottom?

Nice build thread.

Which skirts are you referring to? The side skirts have their own support beam and are only attached to the cross members. The top edge just rests against the body lip (fer now). I was thinking about taping it later to see what it would do. :D

The rear skirts (front edge) "were" attached to the frame via a zip tie and screwed to a 2x4 piece that was
screwed to my rear hitch frame. I'm in the process of reworking a better support setup on the front edge of the rear skirts as soon as I trace out the pattern to make new ones. ;)

The rear skirts won't float up and down but will wiggle side to side. The diffuser/rear pan does move (a little) up and down as the rear axle goes up and down.

Very cool pan BZP! I would love something like that for my Ranger. Do you have any problems with engine temps with the engine bay so sealed? Ireally need to check out your build links next.

Hey d0sitmatr. What year Ranger do you have? I am averaging 30mpg (80% highway). No real mods yet other than an upper grill block and moving my front license plate up to cover some of the lower opening. Just went to synth. trans. fluid and diff. fluid so I'll have to see if that gives me any improvements.

Hi HM
I have a 99 XLT, that has the 3.0L Vulcan engine.
Im averaging about 25hwy, and am trying to push that up to 30hwy.
I have a proposed mod thread here that might give you some ideas:
going for 30+mpg 3.0L ranger
look for posts by the user cons, he has an 04 with a 2.0L 4 cyl he is claiming to get over 40mpg with. he has heavily aero-modded his truck though.

I've enjoyed reading all your threads, BamZipPow, wherever found. Nice work, nicely done! Did you find that Democrat or Republican coroplast gave as good results as Libertarian? I was also wondering about loading the truck to GVWR (and/or rear GAWR) to see about road clearance issues.

Same for certified scale results: how heavy is the truck in normal use, and what is remaining factory payload? There comes a point where the FF/RR rake changes to "nose high" [relatively] -- even with the RM overloads. Call it questions about truck utility if you want. So I hope to see more as you learn more, and I know I'm not alone in following your experiments.

Interstate 45 is easy money for fuel mileage between Dallas/Houston . . nothing like the pain of I-35 from SA to Dallas!!

Didn't make a note of which party gave me a better performance. ;)

I didn't have any road clearance issues with standard driveway slopes. It's the extreme ones that I avoid. :D

I just took out everything from the bed of the truck...including the topper. It raised the back end about 3"...so the clearance on the rear skirts went from 5" to 8". This removal of the topper is in preparation fer working on a simple aero cap. I lowered the diffuser to bring the angle back close to 4°.

I wonder if the belly pan and diffuser will have any effect on the tailgate being up or down now. Guess I'll have to experiment to find out. ;)

Headed up I-45 fer a bedliner so I'll be able to test the tailgate down combined with the belly pan and rear diffuser. I know it's only one run but it will be interesting... ;)

http://i164.photobucket.com/albums/u...0/IMG_7649.jpg

Going up North I got just under 23mpg with the tailgate down and the "ducktail" on the roof. Got 25.53mpg coming back with the tailgate up. This is just as good if not better than with the camper top on. ;)