My quest for 30 MPG - Ford Explorer Gas Mileage Tips

[aldive]

Spoiled?

After further pondering Jeff Draper’s comments on the spoiler that I have ( Lund Windjammer ), I am wondering if the spoiler is not “so bad” for mileage after all.

If the spoiler were a solid wing ( such as found on NASCAR Nextel Cup cars, Jeff’s comments would definitely apply. However, since the spoiler has slots ( see pictures ) that according to the manufacturer, are used to downward deflect air to keep the rear glass clean. This downward air flow would theoretically reduce the low pressure area behind the truck and possibly enhance gas mileage,

A road test with and without the spoiler will provide us some information.

 

[BOLT]

the time...

 

[aldive]

So you are the guy that comes to a crawl on a grade forcing everyone to pass cause you don't wanna add gas and mess up your mileage...? My grandpa used to clip coupons... Talked about it aaaaaall the time...

Whats a grade? Remember I live in Florida.

 

[JDraper]

Spoiled?

After further pondering Jeff Draper’s comments on the spoiler that I have ( Lund Windjammer ), I am wondering if the spoiler is not “so bad” for mileage after all.

If the spoiler were a solid wing ( such as found on NASCAR Nextel Cup cars, Jeff’s comments would definitely apply. However, since the spoiler has slots ( see pictures ) that according to the manufacturer, are used to downward deflect air to keep the rear glass clean. This downward air flow would theoretically reduce the low pressure area behind the truck and possibly enhance gas mileage,

A road test with and without the spoiler will provide us some information.

I hadn't seen any closeups of the windjammer, so I didn't know it had the slots. My assumption was that it was a solid piece, and that would definitely create more drag. It would still be interesting to see what effect it is having on your mileage.

The type of spoiler that I'm thinking would do the best for mileage is like one off an old Plymouth Gran Fury/Dodge Coronet wagon. Back in the early 70's, they had a curved spoiler on the car that was designed specifically to pull air down the rear of the car, not to increase downforce. I'm having a heckuva time finding a good pix of one though....here's what I could find.

 

[JoeDirt]

Holy effects, Batman!

Hmm...either the plate is being intentionally covered, or they are some crazy looking spoiler effects

By the way...my stock explorer (just back from new t-case and rebuilt rear driveshaft) averaged a record 25.6 mpg last night on a 100+ mile trip from philly. The air was about 78 degrees last night with periodic rain on the turnpike...

drove with cruise control between 65-70 mph w/o rain and 50-55 mph w/ rain. (say avg speed=65). No as good as Al's model of efficiency, but not bad for completely stock (roof racks and all).

 

[4X402]

My personal best was at 21.1mpg ona 70 mi. roundtrip from my normal house to my lake and back, thats going by that little display in the console of my X. But i've got the 5.0, city is in the 13 range.

 

[aldive]

I recently replaced the throttle body on my truck. ( http://www.explorerforum.com/forums/showthread.php?t=139454 ).

My hopes are that the larger TB will let the motor be more efficient and a more efficient motor often means better mileage,

We shall soon see .....

 

[aldive]

I wonder if a rather dirty throttle body inside has been costing me mileage? ( http://www.explorerforum.com/forums/showthread.php?t=139457 )

Thoughts .......

 

[Anime]

I would have to say the windjammer spoiler probably IS costing mileage, since even though it does have slots, the fast moving air going over the roof gets "spoiled" not just by going smoothly over it or through the slots, but likely gets caught in the hollow inside and is then forced out when more air displaces it. It's just a guess and I have nothing to prove my aerodynamic theory, but I've installed a few of these things and they just don't appear to be anything more than a cosmetic item. Sure, they probably disturb the air enough to keep the back glass from picking up as much dust as a vehicle without it, but it definitely appears to have a parachute effect going on. It would be interesting to see how the air would flow in a wind tunnel over/through such a thing. Taking it off to find out would be a hassle though, and leaving it off would show the holes.

 

[aldive]

Spoiled, again?

I really like the look of my Lund Windjammer, but I like my gas mileage even better.

After coming to the conclusion that the spoiler might not be bad for mileage and might even augment it, I decided to do a road test to see the significance of the spoiler.

I have the current mileage data ( highway ) with the spoiler in place, therefore, I had to remove the spoiler and do another road test. My spoiler is attacked only with the 3M tape and it was a ***** to get it off; that tape is tough stuff.

The test consisted of a 140 mile run on I75 ( 70 miles S to Ft Myers, short visit with a friend, and back ). The fuel used was Amoco 93; computer tune used – Doug’s dyno tuned 93 tune. The speed was GPS determined.

Previous best mileage with this tune was 31.7 MPG ( see http://www.explorerforum.com/forums/showthread.php?p=1248267#post1248267 post #44 ).

This trial was 147 miles; average speed 69.6 MPH; mileage was 30.4 MPG. Ambient temperature 92 F.

Based on this one test, the mileage was better with the spoiler.

Further, I like the look and I am keeping it.

 

[aldive]

Sure, they probably disturb the air enough to keep the back glass from picking up as much dust as a vehicle without it

Taking it off to find out would be a hassle though, and leaving it off would show the holes.

Actually it doesn't do much if anything to help keep the hatch glass clean.

Taking it off is just a matter of removing the 3M tape. There are no holes; held on only by the 3M tape.

 

[JDraper]

Ah, was worth a try. I'm kinda surprised at the results considering it's construction. Would have been interesting to see what a back to back test (trip down without, trip back with) would have produced.

 

[aldive]

. Would have been interesting to see what a back to back test (trip down without, trip back with) would have produced.

Yes, it would have been. Its just too damn hot to install the spoiler on the side of the road/parking lot.

Maybe another time ( like winter ).

 

[Runnin'OnEmpty]

Aldive, by the looks of that slotted spoiler, it looks more like a 'turbulator' than a spoiler. It apparently causes turbulence behind the hatch, thereby breaking up the low pressure area there. The designers must have figured that out when they added the slots.

I agree that it looks good, and I'd keep it too......

 

[Anime]

I don't think one run is really enough to say one way or the other on the spoiler's effect on mileage, or even any mileage in general. The effect of disturbing the air that I think might increase drag might actually be breaking up the low pressure area as mentioned though. After thinking more about it, it probably doesn't contribute much drag if it's just held on with 3M tape, since as strong as the tape is, driving at 80+m.ph. would probably rip it off if the air flowing over the roof was really getting trapped in the hollow part. I do agree it looks pretty nice, at least from the back, but still feel theres probably a better design option that would do more for your mileage. Lund only advertises the windjammer as a air deflector that keeps the back glass clean though, so it would be something if it improves aerodynamics but doesn't do that. It might be interesting to test the factory type spoilers vs. the windjammer vs. no spoiler over time and see the results.

 

[Rhett]

I wonder if a rather dirty throttle body inside has been costing me mileage? ( http://www.explorerforum.com/forums/showthread.php?t=139457 )

Thoughts .......

I am very surprised that you were running a stock size throttle body.
I thought that you had changed that long ago...

I do not have data to support the claim that a larger TB, or a dirty one, will affect gas mileage. I can say that my mileage data from 4 years ago (with a stock TB) is inferior to the mileage I get today (with a larger TB). But then again, I have done many other modifications in addition to the TB.

Again, I am surprised that you of all people were running a stock TB. (!!!!)

 

[aldive]

Again, I am surprised that you of all people were running a stock TB. (!!!!)

Why? There are no aftermarket TBs for the SOHC? I had to use a Mustang TB

 

[CDW6212R]

I didn't know that the spoiler had a pocket inside of it. That is extra drag, I thought that they smoothly deflected air down. The Ford spoilers just divert air down, with the simple plate style that someone already referred to.

I wonder if it could be helped by filling the pockets with a curved section, to divert air down onto the window. Regards,

 

[MtDew]

Spoiled, again?

My spoiler is attacked only with the 3M tape and it was a ***** to get it off; that tape is tough stuff.


Further, I like the look and I am keeping it.

I agree Al! I have Lund Window air deflectors on my X. That tape is almost bullet proof. Once it's on it wants to stay on!!

 

[davidmmm69]

what about the visors for the windsheild I had one on a old blazer i had years and years ago..