Darby, how's the air tabs?

boilermaker2 · **Posted:** Tue Dec 11, 2007 12:03 pm

I must say that your commitment to the air tabs has peaked my interest and seems like a much less invasive method of saving an mpg or two. Do you have any recent pics? Your pic on another site just has them on top and you've indicated you have some on the side.

Have you put some more on? Have you tried the back side of the gas tank (black color of course)

Have you seen a bona fide increase or has your hypermiler techniques blurred your results?

Sorry for all of the questions, but I think they are cool...especially if they work. I'd like to know your findings (i.e. guinea pig) before I go putting a bunch of little winglets on my rig and get grilled by the family for the insanity. :shock:

Boiler

DarbyWalters · **Posted:** Tue Dec 11, 2007 2:17 pm

I first had only the roof mounted (5) tabs and really couldn't measure any difference...but that does not mean there was not one. Then I finally added 3 to each side. Driveability on the highway (stability in cross winds) feels better and they have added a bit of highway mpg...probably closer to .5mpg or so. I don't think they do any harm and the rear window does stay cleaner when driving in the rain/wet. For the price (about $2.50) a tab...if was cheap to try and seems to give some benefit. I think 11 is plenty...I don't want to look like an Armadillo :shock:

The Air Duct and Grill Block seems to have helped even more:

It is a WIP (Work in Porgress) but definitely helps mileage city and highway. Hard to see the grey air ducting on the passenger side but you can see the grill blocks on the driver side. I will probably block the two open ones this week and rely on the air from under the bumper to cool the radiator/intercooler. The CRD comes up to temp faster and the aero advantage helps a bit. If you put grill blockers on the outside it might be more aero, but it looks better this way. I found the sheet of hard plastic in my dumpster, so the mod is basically free! The stuff is called Glassteel and I just finished cutting the last two so all the sections will be blocked (5) and two left for air ducting.

DarbyWalters · **Posted:** Tue Dec 11, 2007 2:22 pm

I did not put any on the gas tank skid because you are not getting undisturbed air at that point. The rear axle ect. has already taken care of that :wink:

I also dodn't put any on the hood like some do or in front of the wheel wells. They just didn't look right.

The thing is you need to catch the air before it separates from the skin of your vehicle...that is why they are not mounted at the far edge of body panels. You need to catch the air while it is still near the surface and then try to keep it there with the "vortex" effect of the tabs.

BiodieselJeep.com · **Posted:** Tue Dec 11, 2007 6:28 pm

Darby:

With the EHM, do you worry that you'll suck exhaust backup into the engine compartment and potentially into the ventilation system? As it is, I think I'm gettting some into my Jetta and CRD now at stop-lights. *cough* *cough*

DarbyWalters · **Posted:** Tue Dec 11, 2007 6:30 pm

Mine run out the bottom on the drivers side...with the window down at a stop I sometimes see it rising up...lol. I am going to run it all the way to the back 1/4 of the exhaust very soon.

MOSFET · **Joined:** Sat Feb 25, 2006 11:40 pm **Posts:** 295

Darby:

I am not trying to be a wise guy, but are the ones mounted on the sides installed backwards? Shouldn't they be turned around 180 degrees?

boilermaker2 · **Posted:** Wed Dec 12, 2007 10:08 am

MOSFET they are not backwards http://www.airtab.com/how.htm

boilermaker2 · **Posted:** Wed Dec 12, 2007 10:17 am

I like the look of the Air Dam. You solution is much cheaper than what is being discussed on another thread.

You say you are covering all of them. Has this affected temps engine temps with you living in San Antonio? I've noticed how the bottom air dam scoops an incredible amount of ground air into the engine area (including the non-modified air intake) but was wondering if five blocked grill slots in an area with a high of 52 deg today or 60 deg tomorrow was a bit much.

boilermaker2 · **Posted:** Wed Dec 12, 2007 10:19 am

Great pics and many thanks. I think that I am looking at my after Christmas project

On more thing, did you place them between the ridges on the roof or did you space them in line with the ridges on the roof?

Thanks Darby,
Scott

flash7210 · **Posted:** Wed Dec 12, 2007 10:23 am

I like 'em!

I want to try them too. i think the black tabs will blend in nicely with my black CRD.

DarbyWalters · **Posted:** Wed Dec 12, 2007 11:03 am

Placed them between the ridges...made it easy to decide how many and I wanted them at a certain distance from the end.

Free is always good:

I figured since I was trying to increase fuel mileage that free was good...but the quilted covers looks pretty nice too. This pic shows the Air Duct a bit better and the complete grill block. I am going to recut two of the inserts since I found my Dremmel.

retmil46 · **Posted:** Wed Dec 12, 2007 12:37 pm

Have you considered filling in the open areas between the skid plates, essentially an underpan for the chassis?

On the '87 MB I have, most of the underside is covered over by 3 plastic panels, 2 up front for the engine bay and transmission. MB says they're there for 2 reasons - noise reduction for that diesel engine, and aerodynamics. And from what I've seen so far, there is a noticeable difference in fuel mileage when you have at least the engine bay and tranny panels installed.

Might want to try doing a little digging in the hobbyist electric vehicle websites as well. When you're only carrying around the equivalent of 1/2 a gallon of gas, but have a motor that is close to 90% efficient, any useful aero improvements are welcome and usually immediately apparent in extended range the first time you drive the vehicle.

What's your take on using one of the rear window air deflectors vs the air tabs? I know their primary purpose is supposed to be redirecting air flow down over the rear window to keep it clean, but it seems they could accomplish close to the same task - help reduce the vacuum behind the vehicle and thus reduce drag. Myself, I'd go for whatever gave me the biggest MPG gain, but some people might prefer a more "stock" look with the deflector if it did give some of the benefits of the air tabs.

Jeger · **Posted:** Wed Dec 12, 2007 12:48 pm

Do you suppose these would help reduce the effect of crosswinds for a motorcycle? Maybe put them on the saddlebags....hmm or one on top of my helmet? :lol:

I like the idea of the underbelly coverage, seems like it could work!

retmil46 · **Posted:** Wed Dec 12, 2007 2:48 pm

Looking at your pics, and after looking thru their website, going by their spacing criteria looks like you'd have room to add even more on each side - 2 more above the taillight, perhaps 2 just in front of the taillight and above the level of the wheel well, and at least 2 on the rear door above and below the trim strip in front of the wheel well - about 9 total on each side.

Yep, definite armadillo! :lol:

But seriously, they do have something of a "cool" factor to them, and if you end up getting an extra mile per gallon for $2.50 each of the buggers, I say stick away macduff!

I mentioned two in front of the rear wheel well because they mentioned on their website that they work well in that location also - I'm guessing the effect would be similar to installing wheel well skirts.

Was there room on the roof for any more than 5, or is that the practical roof limit as far as spacing and air flow?

In case you couldn't already tell, yes I'm interested and trying to calculate how many I'd need to take it to the maximum effect.

DarbyWalters · **Posted:** Wed Dec 12, 2007 3:05 pm

I have considered some underbelly coverage...but the engine/tranny/transfercase skids do a pretty good job. I do think a lower front air dam would be a big benefit, especially if you covered more of the front tires. You could make it very easy to remove for offroad...I will be looking more at this very soon.

You can of course add many more air tabs...in fact the shape of the rear lights are like an air tab if you look closely. The AIRTAB site likes to tell you to locate the tabs much closer together...maybe to sell more. The thing is you don't want to over do it IMHO.

The problem mounting them by the wheel wells is the shape of the fender flairs...it makes it difficult to mount them properly and they a bit bigger than the flair is wide.

I am just trying to beat the 19city/21combined/23highway with a lifted CRD with armor. So far so good! I am actually beating the OLD EPA Estimates...including better than the 26 highway.

I think (I used 11) that you could order 20 and have a few to test with. Another way to attach them is using business card magnets cut to shape/size. Another guy has done this and they have stayed on at 65mpg or so. You have to figure that the air passing over them will keep them attached.

durangotang · **Posted:** Wed Dec 12, 2007 3:05 pm

I just started wearing one of these....

DarbyWalters · **Posted:** Wed Dec 12, 2007 3:14 pm

That would make anyone mad :twisted:

chrispitude · **Posted:** Wed Dec 12, 2007 4:14 pm

Every time I read this thread and look at the pictures (especially the pictures!), the theme song from the late 70s TB show "Buck Rogers in the 25th Century" show pops into my head...

- Chris

DarbyWalters · **Posted:** Wed Dec 12, 2007 6:49 pm

Time Trial Gear is always Kewl...

ATXKJ · **Posted:** Wed Dec 12, 2007 8:40 pm

Please note - armadillos are perfectly at home in Austin.
http://www.armadilloworldheadquarters.com/awhq.htm

Darby, how's the air tabs?

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