6.7 68RFE MPG pulling

[DaleBryant]

Okay I want a 07. 5 or 08 6. 7, 68RFE . Can any one get me an idea of the MPG towing around 12k 5th wheel ? I do a lot of my trips in the west through the rockies and my 03 is around 11. 2 overall by paper figures. I don't waste any time as when on any freeways I'm around 70 to 75 most of the time.

 

[AKaiser]

I don't know, but I speculate that it will be about the same, but better than a gasser by any means. Pulling 12K and pushing all that air at 70+ you're just going to use fuel.

 

[CUMMINZ]

You can look for 8-11 till it is broke in.

 

[Doughboy21kd]

You can look for 8-11 till it is broke in.

Thats about what i'm getting and thats turnin 35" tires too... ... Any idea when i will see my biggest increase?



On my 06 i seen my biggest increase at 10k but i also only had the truck til i had 15k on it, then traded for this 6. 7 i have now

 

[CUMMINZ]

What gears go you have and what are you towing?

 

[Doughboy21kd]

What gears go you have and what are you towing?

I am towing a Hydraulic dump trailer (4k to 14k) plus whatever truck weighs... . And a 32' travel trailer haven't weighed it yet with everything in it... .



Gears are 3:73

 

[Jeepstang]

I pull about 10k and average 9-11 towing but I have a heavy right foot

I get 14-18 empty I have 3. 73 Ratio

 

[trqmnstr]

What rpm's do you guys run at 70mph with 3. 73 and 4. 10 using the 68RFE?

 

[CUMMINZ]

1900 with 4. 10s.



CUMMINZ

 

[trqmnstr]

Nice, so the best of both worlds. Low gear for heavy loads and also pulls low rpm with the double O/D. Doesn't get much better than that. I don't see a need for the 3. 73. Seems like they'd be running way too low of rpm's on the highway.

 

[Wolfy]

What rpm's do you guys run at 70mph with 3. 73 and 4. 10 using the 68RFE?

68RFE/3. 73



1750 rpm @ 70mph (1500/60, 2000/80) right on the money.

 

[klenger]

Answers here: http://www.klenger.net/dodge/general-reference/gear-speed-calculator.pdf

 

[trqmnstr]

I can't seem to open up that calculator for some reason. What would 5th gear bring at 70mph with 3. 73? Would be nice to cruise 80 empty in 6th and just drop to 5th when towing. Hmmmm.

 

[Wolfy]

I don't see a need for the 3. 73. Seems like they'd be running way too low of rpm's on the highway.

The torque curve on this engine is very flat. 1500-1600 rpm is getting into the peak. You can get lower top gears by using the gear-limiting setting, if your load or incline requires more horsepower. You can use whatever gear you like as "high".



Some posters have commented just the opposite; "... don't see the need for the 4. 10. "

 

[Wolfy]

I can't seem to open up that calculator for some reason. What would 5th gear bring at 70mph with 3. 73? Would be nice to cruise 80 empty in 6th and just drop to 5th when towing. Hmmmm.

3. 73 in 5th:



68mph=2200rpm



71mph=2300rpm



(i. e. , 70mph=2267rpm)

 

[klenger]

Complete Excel Worksheet

Complete PDF File



Here's the 68RE only part of the gear calculator as a quick loading image file.

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[Texas Ted]

10 mpg towing 14k. Some mountain driving included. I only have 2k miles on the truck. Ted

 

[Sky]

My total truck weight was 8850 yesterday, I drove 250 miles and got right at 14 MPG. When I tow about 3-6k I average 10. 5 mpg. Disappointing.