On towing with 31's and not regeared (yet)

[lfhoward]

I just thought I'd share my experience. I also want to document some numbers for after I eventually go to 4.10 gearing.

I have:
30.5" KO2's, 3.73 stock gearing, automatic, aux ****** cooler, tow package

I towed my camping trailer (2500# approx) to Michigan from Pennsylvania and back.

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More info on the trailer: http://tnttt.com/viewtopic.php?f=50&t=62581

Going West:
I kept it in tow/haul mode to lock out overdrive and went 65 mph on the way there. The Jeep was fine except when it would lose speed on hills and kick down to 2nd gear, sending the RPM's up to 4500 or so. I would take the cruise control off and adjust my foot to lose a little speed but keep it in 3rd if possible. The RPM's averaged about 2800 at 65 mph on the flat. MPG: 10 (calculated at the pump, gallons / miles driven). Going 70 mph in 3rd gear meant rpm's at the 3200 range, which was even less fuel efficient, so I didn't do that.

Going East, part 1:
The first part of the trip I caravanned with trucks at 65 mph, taking advantage of their slipstream. With tow/haul engaged, I got 11.2 MPG on the flat in Ohio. I tried to follow trucks that had side skirts on the trailers, to maximize aerodynamic efficiency. Hey, that got me a 12% improvement in MPG!

Going East, part 2:
The second part of the trip, through the mountains of Pennsylvania, I tried a different strategy. I used tow/haul up hills, but manually turned it off going down hill so the transmission could shift into 4th and reach 70 mph. (Overdrive was not strong enough to maintain highway speed on the flat while towing the trailer.) This strategy netted me a whopping 12 MPG. You would think this still *****, but it's 20% better than leaving it in tow/haul mode constantly! That adds up on a long trip.

Using my Scangauge I was able to watch that both coolant and transmission temperatures stayed happy the whole trip. (Coolant ~200 and Trans ~145)

Anyone running 31's who has regeared and willing to share MPG stats for towing a comparable weight trailer?

 

[tommudd]

Trying to think what size tires I had on the 04 when I moved my wife to Boston from To-le-do
I think at the time I was on 265-70-16s , and 4.10s with my loaded 6 X 10 trailer , very loaded with books, clothes, furniture etc
Through Pa etc I got 16-almost 17 running 65, 70-75 when possible
I never used Cruise Control
When I moved her back , she acquired more books, more " stuff with trailer full, inside of KJ full and three suitcases on the rack I got about 15- 16 If I remember right
When she moved down to Winston Salem I had the 03 towing the same trailer down 77 through WVA, VA and into NC
As anyone knows that is a crooked, hilly road for sure
I got 17.5 running 70 most of the way with 4.10s and 265-70-16s
Coming back, trailer empty averaged almost 19.5 running 75-80
again never running cruise control
I never follow trucks close enough to get in their slipstream, being a professional driver for a few years disliked anyone doing that , if for some reason I needed to avoid anything, they would be up my butt in two seconds . Plus most couldn't keep up with my Pete

 

[tommudd]

Oh and on the 04 I had fabbed up a deflector on the rear part of the roof rack to help air flow over the trailer better

 

[JeepJeepster]

You can see the trans temp with the scan gauge on a KK?

Wild that your trans temp stays that low, mine will quickly go over 200F when towing. Even with O/D off and cruising along. I wonder where the temp youre seeing is coming from?

What sortve trans cooler setup does the KK have? Only the aux cooler?

Im planning a trip to the smokies this summer with a ~2500lb popup and Im curious how the KJ will do. It has 4.10's and 30" tires. I've not towed with it since regearing, but she always struggled before. Felt like I always had the go pedal buried and would always slow way down on the hills. I try not to let it downshift into 2nd though.

The 3.7 only has 235 lb/ft of torque, so I guess we shouldnt expect much. Its wild how different towing with a 5.7 WK is when compared to the KJ. It will maintain 70 in O/D 1 no problem.

 

[lfhoward]

Mine has the stock ****** cooler as part of the radiator, and then it also has an external aux ****** cooler that I installed in front of everything. That aux cooler gets air blasted directly on it at highway speeds. Now in the city, the ****** temp edges up closer to 200 or more because there is less air movement past the aux cooler.

 

[Cardhu]

I used to run a similar weight boat on 245 75 16 duratracs on stock gears and auto.

ran 90 km/h at 2400 rpm and got 15 mpg.

Just for another data point. If i was going to keep the jeep 4.56 in a jba diff was the next step.