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Discussion Starter #221
At altitude:
Less air = less fuel mix = better MPG..... also = less power

Better MPG's is assuming you don't floor it everywhere to compensate for the lower power available
I'm picking up what you're putting down... but work is work. Our vehicle didn't get lighter... I suppose less air means lower drags, but I would think most other frictions would stay the same. The bottom line is HP is a measure of work and it should take the same (or similar) amount of work to move us. Obviously it didn't but I'm not sure why. :) :laugh:
 

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I'm picking up what you're putting down... but work is work. Our vehicle didn't get lighter... I suppose less air means lower drags, but I would think most other frictions would stay the same. The bottom line is HP is a measure of work and it should take the same (or similar) amount of work to move us. Obviously it didn't but I'm not sure why. :)
That is my take on it, too!

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My point is that HP is actually work per time. And as long as you don't push the pedal down harder, the lower available HP means you are actually driving slower (or more critically - accelerating slower).... which means better fuel economy.
 

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I'm picking up what you're putting down... but work is work. Our vehicle didn't get lighter... I suppose less air means lower drags, but I would think most other frictions would stay the same. The bottom line is HP is a measure of work and it should take the same (or similar) amount of work to move us. Obviously it didn't but I'm not sure why. :) :laugh:
My point is that HP is actually work per time. And as long as you don't push the pedal down harder, the lower available HP means you are actually driving slower (or more critically - accelerating slower).... which means better fuel economy.

I would expect that air drag is substantially greater with that trailer setup. Air drag has substantial effect on fuel economy at highway speeds.

As to 'accelerating slower ... means better fuel economy': not necessarily so if what you are accelerating is heavier.
 

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Discussion Starter #225
I would expect that air drag is substantially greater with that trailer setup. Air drag has substantial effect on fuel economy at highway speeds.

As to 'accelerating slower ... means better fuel economy': not necessarily so if what you are accelerating is heavier.
We were never unhooked from the trailer... All my numbers are WITH it. I'm not arguing the trailer adds drag at all.... Honestly, I'm not even arguing at all.. just chatting. :)
 

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I just finished a week camping, during which I towed a 2000lb popup coleman camper in a fully, and I mean absolutely packed, 2015 TH 3.2L. The trip was mostly highway, during which I averaged 70-75 mph. There were also large stretches of significant uphill, climbing several thousand feet in a few miles. On the going trip, I averaged 21.7 mpg over 107 miles. On the return trip, I managed to get 24 mpg over 84 miles (the return trip had fairly significant downhills, obviously!). I gotta say, I think aerodynamics play a big role in this situation. My camper rides much lower than the TH, and is only a few inches wider to either side. Worth some consideration for those with towing concerns.

I would like to add that the KL towed this camper with absolutely no problem. Even at those speeds, there was no noticeable change in control or handling. I had three passengers, once of which was my father, who commented several times how it pulled the camper like it wasn't even there. He has been towing this thing with a 12 passenger Ford van since he bought it in '87.
 

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Morning everyone...

I'm curious what you see fuel consumption wise when towing. I'm mostly interested in insight from the 3.2L TH owners, but feel free to comment for others that may search out or be interested.

I have never been satisfied with our KLs economic performance, but this weekend was our first time out with it while pulling our ~1600lb overland trailer. I averaged 10.1 MPG on a largely interstate trip where my speed was kept between 70-72 MPH. It seemed our little KL just didn't have enough grunt and spent large amounts of time in 4th and 5th gear (3000-4000 RPM). I know our trailer is by no means aerodynamic, but this is absolutely absurd. We purchased our KL TH to be a forestry road light overlanding rig, but with a 200 mile range there is no way I can use it for this.

On the way home I did everything I could get the best fuel economy; no cruise control, easy on hills, lots of coasting... Still I only improved the return trip's economy to 12.8 MPG.

If this is what I can expect on fuel usage I fear both Jeep and we made an EPIC mistake on vehicle selection.
This was a good write up I had the same questions.
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29429FBD-01B5-49A7-BAFF-02658470F241.jpeg
 

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At altitude:
Less air = less fuel mix = better MPG..... also = less power

Better MPG's is assuming you don't floor it everywhere to compensate for the lower power available
I think most importantly, higher altitude= less air density= less aerodynamic resistance for the same velocity.

Highway mpg is pretty much always limited by aerodynamic drag as opposed to gearing, especially in our cherokees, it would make sense that especially when towing, altitude would have a significant advantage.

The less fuel mix argument works, but only so far as you use the same throttle input. Per the same throttle input, you'd get less power, equal to less acceleration, which in turn would give you a bit better effifiency.

The last thing that would yield better mpg at altitude is that usually, when you're going over a mountain, the road is twisty, and as a result the speed limit is lower than on the interstate, so again, lower velcoity=less drag=better mpg.

I'm about to tow a light utility trailer (aluminum hf clone weighing 250lb empty, will probably have ~100-200lb of cargo in it) with wood 2x4 sides going up 3ft from sea level (SF bay area) up to a bit over 5000ft in the Sierra Nevada mountains and back this coming weekend ~140mi each way and I"m interested to see what kind of mpg I get with my 2.4L Cherokee.
It's not aerodynamic, but it does tuck in completely behind the cherokee.

I will probably be sticking to 60-70mph at most.
 

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I ended up taking more cargo than I anticipated. There were 450lb worth of people, ~200lb in the back of the Jeep, and ~300lb in the trailer with a tarp on the front and top.
I ended up averaging 22.1mpg on the round trip (310mi sea level up to 5000ft and back) going 65mph.

I noticed that this time, the coolant temp stayed around 220F while chugging along the highway with the AC on. Whenever it would get up to 234, it would rapidly go down to 190 with the fan kicking in.
I also noticed that the oil temp would rise from dead center, to almost 2/3 whenever coolant temp was around 220 and above, and would go back down to halfway whenever I had a downhill stretch.

I wonder if this is due to the active grill shutters staying closed at highway speed. The oil cooler is right in front of them, so when they are closed, I would imagine reduced airflow through the oil cooler.

Transmission temp stayed at 165-170 except when I was stuck in traffic climbing over the Altamont. It went up to 189 there and back down to 165 as soon as traffic cleared up.

I could definitely feel the trailer's weight climbing up the Sonora pass. There were parts where the tigershark had to crank it up to ~5000rpm in order to not lose velocity.
 
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