Tested: Airtabs on a mini van, A-B-A - no measurable effect

[sid]

Agree: All ideas should be tested. Even ideas initially thought as "dumb" could give an unexpected result leading in a new direction, even if not useful itself.

[hendan]

Originally Posted by PaleMelanesian

You might want to look at Ferrari, Lamborghini, McLaren, Bugatti, Saleen, Corvette, etc to see what works and doesn't. Guess what? They're all built on a teardrop streamlined shape, because that IS what works.

Not all of those have impressivly low Cd's either. But I guess there are reasons for that (you got to keep it on the road some how.)
Anyways, thanks for debunking a theory!

[aerohead]

Originally Posted by Tundra Boy

This is by now a dead thread I guess, based on the last posting date. However, I have a couple comments.........

While the test methodology was decent, why only test at 55 mph? Is that the speed you regular thread contributers drive? How about at say... 75 mph.

Secondly, you tested a vehicle that already was good for 33 mpg. Obviously not to many aerodynamic issues to begin with.

I wandered in here looking to improve the lousy mileage that I get with my Tundra; which is currently getting around 14 mpg.

I have read quite a bit of another thread regarding the streamlined toppers that several have made. I have seen some mention of approaches such as Kamm back but little or no mention of the Coanda effect for example.

Most of your efforts seem like a throwback to the 1930's and the streamlining teardrop efforts of that era.

You have not done anything to convince me that the Airtab approach is without merit. I guess that I may actually risk some of my own precious resources to find out for myself.

I think that many of you are close to engaging in pack mentality at this point, having so much time and effort invested in one particular approach that incidentally seems to greatly detract from the functionality that led to the purchase of a pick-up truck in the first place.

There. How was that for my first introductory post? Kind of like a fart in church I suppose.

Cheers!

The turbulators are intended for notch-back type cars which have a trunklid for separated flow to reattach to,and at a faster angle.
If you run a tonneau on the Tundra,the tabs might help you cheat a bit on wake area downstream.

[pnambic]

Hey, I'm new (obviously) but I have a question:

33mpg in a minivan as your starting point?
Seriously?

The gubment says 23 mpg highway.
( Since I don't have 5 posts, you'll have to cut and paste to verify or take my word for it:
w w w.fueleconomy.gov/feg/bymodel/2005_Pontiac_Montana.shtml]Gas Mileage of 2005 Pontiac Montana )

Forget the airtabs, what have you done to get that van to 33mpg?

In my bone stock '08 Dodge Grand Caravan (3.8), I once got 25mpg on a tank with the cruise set to about 60 going up a relatively flat state road between Indianapolis and South Bend (SR 31) last winter. But I generally avg between 22 and 23 mpg highway (loaded for vacations with me, the wife and our 4 kids).

I'm looking to improve the mileage of the van via (low visual impact due to my wife's lack of tolerance for anything radical looking) aero mods but am looking to start with proven ones. I made an undertray for the front end of our old '99 Grand Voyager from sheet aluminum that was mildly successful. On the interstate, it made a noticeable improvement in handling (around large trucks) and might have improved highway mileage by about a half mpg, but the aluminum would make annoying noises over bumps as it resonated. I'd like to get my hands on some of the rubber side skirting that I see on semi's, but thus far they have eluded my searches.

But back to my question. What did you do to get that Montana to go 33 mpg?


Thanks!

- Dan

[Joenavy85]

Originally Posted by pnambic

But back to my question. What did you do to get that Montana to go 33 mpg?


Thanks!

- Dan

he adjusted the nut behind the wheel. No, i'm not calling you a nut, that's just the expression. by changing my driving techniques i went from getting 15-16 MPG average in my jeep, to getting 16-17 MPG while towing a fully loaded (volumetrically at least) 5'x8' UHaul trailer (along with the Jeep being full), to getting 23-24 MPG on the highway.

[MetroMPG]

Hi pnambic -

Note the conditions where 33 mpg was obtained:

- reading was taken at 55 mph, (ie. does not include the MPG hit of getting up to speed)
- with a fully warmed up drivetrain & tires,
- on a nearly perfectly flat stretch of road,
- in zero ambient wind,
- mild conditions (no AC or heater use)
- roof racks removed,
- tires aired up to spec.


The van wouldn't have returned 33 MPG over the entire round trip it took to conduct those tests. Not sure what this vehicle is capable of getting in regular driving, because it's my brother's . I don't drive it very often.

[sid]

Just another data point:

I tried Airtabs on the back of the topper for my pickup. 18 were mounted, 10 across the top and 4 on each side. I left them on for about four weeks. I didn't do any formal A-B-A testing, just my normal driving.

The result: If anything, they seemed to hurt fuel economy by about 1 mpg. The fill ups that were closest to identical driving conditions in my fuel log (Grayranger) were 3-15-11 with Airtabs and 4-6-11 without. The tanks between when the log says the back was changed and when the back was returned to original are with Airtabs (2-24-11 to 3-23-11).

But everyone who saw them said they looked cool. Unfortunately, that doesn't mean much to me. So they have been removed.