MPG Experiment

[Gren71]

Day 4
Trip 2 - RULED OUT
22.6mpg
-Trip ruled out due to 10+ mph sustained head wind combined with inclement weather.
-Interesting to me that, despite the weather factor, I still had a MPG average in the same range as one of the days in the data pool.
-AF 1 present. In addition to fewer steering inputs, I noticed the JT tracked straighter with a head wind. And even while following behind a large tanker truck where the turbulent draft would ordinarily cause me to wiggle a little.
-AF 2 present, but at a different incline. This time it held 8th longer on an on ramp. Not a lot longer, but definitely held the gear farther and then shifted back into 8th sooner than normal. This one may have more to do with the weather though.
- AF 3 present

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[Gren71]

So far looks like you gained a mile and a half per gallon!

Yea im seeing more positive results than I anticipated. Time will tell if they continue, but so far the data is promising and interesting.

 

[KWin]

Based on your finding I'm thinking about adding the air dams, I have a sport s max tow, and am stock stock stock, and struggle to maintain 18mpg driving like a granny. Getting an extra mile per gallon would save me roughly $200 per year.
Any Rubicon owners (with 4.10 axels) want to share their mpg? I'm wondering if bigger wheels actually helps mpg... <totally not me justifying buying bigger tires ?
And if I'm stuck at 18mpg thats okay, I get a ton of smiles per mile with this truck!

 

[Gren71]

Day 5
Trip 1 - RULED OUT
20.5Mpg @ average 60mph with nasty cross wind and gusts. 29d ambient tempt
-Ruled out due to inclement weather impacting the road conditions, and not being able to safely maintain the test speed of 65mph.
-I continue to be impressed with the Bridgestone Dueler ATs. They handled the snowy roads wonderfully. Not entirely sure where all the hate on these tires comes from since ive had nothing but positive experience with them. Enough that I may end up getting another set of bronco take offs if I see them at a good price.
-AF 1 Present
-AF 2 did not occur
-AF 3 Present

 

[BaliMawr]

Based on your finding I'm thinking about adding the air dams, I have a sport s max tow, and am stock stock stock, and struggle to maintain 18mpg driving like a granny. Getting an extra mile per gallon would save me roughly $200 per year.
Any Rubicon owners (with 4.10 axels) want to share their mpg? I'm wondering if bigger wheels actually helps mpg... <totally not me justifying buying bigger tires ?
And if I'm stuck at 18mpg thats okay, I get a ton of smiles per mile with this truck!

I'm thinking the same thing. I've got a JTMT on order, and even if I bolted the ugly things on just for long trips, it might be worth it.

 

[ShadowsPapa]

I've done a bunch of reading and observing as far as drag coefficients on trucks, what things factor in, how they change it and so on.
For example, note that modern pickups have a seal between the front of the bed and the back of the cab? Yeah, testing showed that gap increased drag as air wanted to move in there instead of flowing nicely down the side. I can't recall if it was GM or Dodge (RAM trucks) that specifically mentioned that.
Running boards that integrate nicely into the shape of the vehicle can help - GM found some help with the round tubular ones but the best ones were similar to what the Overland comes with (makes sense - it's also the model sold for the best economy and highway driving)
Now get this - tonneau covers - tests show real world improvements and a GM engineer commented that in his observations the soft tonneau covers were slightly better than the hard ones....... Another test I have a copy of showed that the tonneau cover effect also varied by truck, not just by length and type of cover. The same type cover on a Ram may have a different impact on drag than that cover would have on a Ford of the same bed length.
So all one can say is "you may see an improvement of between 3 and 6%" just as an example.
What I've found in my studies is that the actual effect varied with the TRUCK and the bed length. Now that makes total sense as the drag of each truck model and bed length is going to vary. a 5.5' bed will have different characteristics than a 6' bed would. The shape of the cab matters.

The top edge of modern truck tailgates - that's not for style and looks. That top edge with the flat top and sort of a wing or protrusion to the back - reduces drag.

There's a whole lot of semi traffic where I live - near where I80 and I35 meet and cross. You see a lot of trucks with fillers in the wheels, bumpers and other items that shield the front edges of the front tires (like Jeep did with the bumper and those bumper-to-fender filler panels) among other tricks to reduce drag and at the same time reduce fuel costs.

Gotta run........... have some more stuff but processes in the shop call me LOL

 

[Gren71]

I'm thinking the same thing. I've got a JTMT on order, and even if I bolted the ugly things on just for long trips, it might be worth it.

Not sure of the JTmt comes with this bumper any more or not. I feel like ive seen a couple folks posting them as a new buy on the fourm and they had a standard bumper.

I was fortunate enough to get the bumper off of a forum member for $50, with made this a VERY cost effective experiment to perform. The real cost of adding these is something Ill have to put together. As in the cost to buy the bumper and the airdams if your JT didnt come with them.

That being said, if some one has the bumper and cut their air dams already...let me know. I had purchased the air dams separately before making the deal with the forum member. So i have a set sitting in the garage I can send to who ever needs/wants them for what they cost me. Save you a couple bucks that way.

 

[BaliMawr]

Not sure of the JTmt comes with this bumper any more or not. I feel like ive seen a couple folks posting them as a new buy on the fourm and they had a standard bumper.

Those winglets don't look super complicated. I'm sure I could fab something up out of aluminum to fill that gap. Might even look better. Or heavy plastic sheet. I was assuming there would be piles of the damned things lying around like so many stock bumpers..

 

[ShadowsPapa]

Those winglets don't look super complicated. I'm sure I could fab something up out of aluminum to fill that gap. Might even look better. Or heavy plastic sheet. I was assuming there would be piles of the damned things lying around like so many stock bumpers..

Here's another reason I'd like those gap-fillers (aside from MPG) -
A lot of the stuff that comes at my windshield is from my own front tires. I have watched as spray on a dirty road is thrown forward over the bumper by the tires and the air flow turns it and blows it right back at me! It's weird and cool to watch the spray being shot forward from the tires stop, and almost in slow motion, change direction and come up over the hood and fenders at me.

The top of the bumper ends is always loaded with sand and mud and slush.

 

[danimal2000]

How are you consistently in the 20+ MPG? I never come close! Recent trip from Chicago to New Jersey, long stretches of highway in between. I never got more than 19 MPG and that is almost completely highway driving. I have a fully stock Willys, only thing I added after the dealer was a tonneau cover. City driving (my daily commute) i get 15ish. i know i need to work on the lead foot a bit, but i would love to get closer to 18 or so

 

[Gren71]

How are you consistently in the 20+ MPG? I never come close! Recent trip from Chicago to New Jersey, long stretches of highway in between. I never got more than 19 MPG and that is almost completely highway driving. I have a fully stock Willys, only thing I added after the dealer was a tonneau cover. City driving (my daily commute) i get 15ish. i know i need to work on the lead foot a bit, but i would love to get closer to 18 or so

Not sure what I do differently than you specifically haha but the lead foot is certainly a factor.

i do use cruise control as often as i can, and do my best to gradually accelerate instead of gunning it. It definitely had a LOT to do with tires. If you have the willys Mt tires thats probably the culprit for your missing mpg. I doubt it makes a huge difference but I religiously use this stuff called fuelOx, dang near every tank.

I also do primarily highway driving, which increases my average MPG since I get the best mpg during long distance highway driving.

 

[Gren71]

~*~*~*~*~*~*~*~*~
The experiment is on hold for now.
~*~*~*~*~*~*~*~*~
I dropped my JT off for a routine oil change and to have some JL rims installed. The service tech called and asked if I wanted some scheduled maintenance done that is up due to mileage, to include a 4x4 service where they change my dif fluid. I agreed, thankfully.

The service tech called me a little later and said that when they pulled the rear plug they found "a huge chunk of metal on the magnet" and "think something may have exploded". (I have a good relationship with the service tech so I know the exploded was a bit of hyperbole, was actually pretty funny. to my sense of humor at least)

I havent heard back yet so im sure its something that will have the JT down for a couple days. Which will make work interesting...But this means that the experiment is at a pause. It may even be deferred for a little if they have to replace my rear gears since Ill have to follow a break in period for them and, im assuming, new gears could negatively impact my MPG.

 

[Kevin_D]

-I continue to be impressed with the Bridgestone Dueler ATs. They handled the snowy roads wonderfully. Not entirely sure where all the hate on these tires comes from since ive had nothing but positive experience with them. Enough that I may end up getting another set of bronco take offs if I see them at a good price.

I bought a set of the Dueler A/Ts after being thoroughly disgusted with the H/Ts. I’ve been very pleased with the performance of the A/Ts. I’ve got about 35k miles on them, and they’re about 1/2 used up.

That being said, if some one has the bumper and cut their air dams already...let me know. I had purchased the air dams separately before making the deal with the forum member. So i have a set sitting in the garage I can send to who ever needs/wants them for what they cost me. Save you a couple bucks that way.

Do you know if the air dams will fit the, “Premium,” Sport S bumper?

And keep up the reports when you can…

Kevin

 

[ShadowsPapa]

Hypoid gears - higher friction when new, then the burnish and smooth and "break in" - I hope nothing exploded and that chunk isn't like 1/2" diameter or anything - but honestly, even on my 193,000 mile differential a while back, the only thing that came out was old fluid, maybe a bit of sparkle to it if you looked REALLY close (and that was with a B-B size piece out of one of the carrier bearings!)
So you should see nothing coming out, no flecks, no flakes, no sparkles, and definitely nothing chunky. Dark is ok, chunky, not so ok.
Good luck and really am looking forward to what you come up with. Few would be so brave as to, in public, no less, try for mpg instead of how tall you can lift it and still get in and see the road.

 

[Gren71]

I bought a set of the Dueler A/Ts after being thoroughly disgusted with the H/Ts. I’ve been very pleased with the performance of the A/Ts. I’ve got about 35k miles on them, and they’re about 1/2 used up.
Do you know if the air dams will fit the, “Premium,” Sport S bumper?

And keep up the reports!

Kevin

happy to see another dueler at fan! I think they get a bad rapport being oem...I certainly balked at them initially. Which cost me when I swapped back haha

If the premium bumper is the same pumper in the pic below then they will not. They only fit the standard bumper in the picture in the first post.

Now another fella, I think in this thread, said he would make something that would work. May be worth a collaboration between the two of you that if he is able to make something worth it you share the cost of his R&D. Just food for thought.

The bumper on the right, which is the same as the one i have on the gladiator now, is the only one I’m aware of that can take the Euro air dams. If the bumper on the left is the “premium “bumper then it cannot take them.

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