Gas mileage and air deflectors for vans

[Glenn Baglo]

Just trying to help.

[Rob in Santa Cruz]

Came with my first TT, three TT,s later I’m still using it.

Must be located as far back on the TV as possible and if it’s to far from the back of the TV to the TT can actually cause a small reduction in MPG due to created suction between TV and TT. (I’m told)

I use it because it seems to reduce buffeting, as I have High Lift axel and 15” tires so TT sits pretty high above my Highlander. It definitely keeps bugs off the Casita.

Sometimes I think it helps with MPG and sometimes not. If so not much.

I adjust it to deflect the airflow just enough to not have bugs on the TT.

[thrifty bill]

I put the success of these deflectors for reducing mileage right up there with the magnets people put on fuel lines.....

But as a way to keep debris off the front of your trailer? Probably a good idea.

[Carl V]

Trying a deflector is on my list.
I see some go by in the used market for just a few bucks. If it's not worth the hassle I'll just sell it back.

I'm not expecting a huge improvement in fuel mileage. Some people say they are saving fuel, some say it's useless. I think most people have no idea how to install and adjust them properly.
My plan would be to try it on a level stretch of highway for some distance, round trip (headwind then tailwind) and drive the same run again without the deflector. My Scanguage should be accurate enough to measure any fuel mileage difference. Could be an interesting experiment.

One thing most people agree on, it really helps with the bugs. It fuel mileage doesn't improve much, I think it will be worth keeping it just for the bugs.

[Thomcat316]

EcoModder.com is a great resource for design and implementation of stuff like this. You can use their regular search or use the Google "site:ecomodder.com search-terms-here" syntax for more targeted searches.

There's a whole aerodynamics subforum, and you're not the first person to want to do this.

[Thomcat316]

Also, too, I've seen folks talking wind tunnels - yeah, if you have infinite cash...

If you want to see turbulence and airflow on the cheap, look to "yarn tufts", taped all over the back half of the van and the whole trailer, then videotaped on a calm day (no crosswinds) from two lanes away to reduce Bernoulli flow effects.

You'd have to do this both with and without the deflector.

[Conch]

If towing on interstate highways for long trips at or above 65mph, I expect you’d be well served by a properly designed deflector/spoiler, with perhaps as much as a 10% gain. Sixty & below not noticable.

[Doctor Harold]

Originally Posted by thrifty bill

I put the success of these deflectors for reducing mileage right up there with the magnets people put on fuel lines...

And putting clothespins on the fuel line for vehicles with carburetors to cure vapor lock. Lots and lots of clothespins...

https://itstillruns.com/use-clothesp...k-7971011.html

I guess 5 is the magic number. or try wrapping the fuel lines in foil if the clothes pins don't work.

FYI: If you have "vapor lock" your fuel pump pressure is weak and you need a new pump, not clothespins.

YCMV (your clothespins may vary).

Harold

[CompactJR-Sailor]

We have used an adjustable deflector for years. First behind a old Chrysler Town and country pulling a compact Jr. Milage went from 14 to 19. In Florida we have lovebugs about once a year. I adjusted it as low as possible so no bugs hit the trailer

[CompactJR-Sailor]

We have used an adjustable deflector for years. First behind a old Chrysler Town and country pulling a compact Jr. Milage went from 14 to 19. In Florida we have lovebugs about once a year. I adjusted it as low as possible so no bugs hit the trailer

[Ice-breaker]

Originally Posted by CompactJR-Sailor

We have used an adjustable deflector for years. First behind a old Chrysler Town and country pulling a compact Jr. Milage went from 14 to 19. In Florida we have lovebugs about once a year. I adjusted it as low as possible so no bugs hit the trailer

I hate scrubbing the bugs off of the front of my Escape. I have often thought about constructing a wind deflector for the roof of my FJ just for the purpose of reducing the numbers of bugs that I have to scrub. If there is a concurrent improvement in gas mileage while towing while using the deflector, well that would be a bonus!

[Raspy]

I'd like to believe it, and I'd run right out and install one myself if true, but to claim a 30% improvement in mileage from nothing more than that wing in the photo, is really a stretch.

Maybe you should put one on each side of the car too, for a total or three, and get a 90% improvement in mileage! Don't put too many of them on, or the gas tank will start overflowing as you drive!

[Alex Adams]

Originally Posted by Raspy

Maybe you should put one on each side of the car too, for a total or three, and get a 90% improvement in mileage! Don't put too many of them on, or the gas tank will start overflowing as you drive!

Don't forget to put the tapering cone on the back of the trailer to eliminate the drag causing eddies as well!

[FRED SMAILES]

Originally Posted by nor1492

I tow my 14' camper with a 2000 Dodge Grand Caravan. I am considering attaching a panel set at a 40 degree angle to the roof of my van at the back to deflect air over my camper, which is about 2-3 feet higher than my van roof. Will this improve my gas mileage, and is it worth the effort? I have the materials to make something with a deflector panel about 4 feet wide and about 20 inches tall. This would attach to the stock roof rack.

I breezed over the posts and never noticed any indication of how many miles you tow the trailer,, say per year or at what speed so there isn't an answer to your 2 questions.
fred

[Thomcat316]

Originally Posted by Alex Adams

Don't forget to put the tapering cone on the back of the trailer to eliminate the drag causing eddies as well!

Interestingly enough, that would create a large savings in fuel, especially if it were an increasing taper that had a smooth transition from the maximum section.

We're designing this into the fiberglass fiver we're going to build.