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What is everyone getting for fuel mileage towing over the interstate?? I was pulling around 3500lbs this past weekend and the fuel mileage was pretty low to what I thought it would be. I drove over 700 miles on Saturday and went through two tanks of fuel!!!! I got around 11 miles a gallon on the first tank with the trailer empty and the second tank I got 10mpg!!???

Alright folks..... Is that normal for these trucks to get that kind of mileage??? I was cruising anywhere from 65-75 miles an hour on the interstate up and down hills.........I figured that it would still hover around 15 or so miles a gallon......?????

Should it be any better than that or is that normal????
What is the best things that can be done to increase this?????:confused013:

Thanks,
 

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Mopar1973Man.Com
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Something to consider is wind drag... Just the truck alone will double its wind drag from 55 to 65 MPH... Now adding a trailer... Then adding more speed... This is totally normal...

Some thing I've found that might enlighten you...
Better MPG's

I can haul load like this...




And still pull no lower than 14 MPG. Because I understand wind drag and the areodynamics of the truck. So I normally try to hold to 55-60 MPH while hauling heavy...
 

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I understand that fact, but what about my truck. I make around 18-19 cruising 65 and 20-21 cruising 75. I go home every weekend, the same way but one weekend I will cruising 65 home and 75 to college. Next weekend the opposite, next I'll do 65 both ways and next 75. Every time I make 1-2 mpg better cruising 75. But thats at 22-2300 Rpm which I believe is my "sweet" spot. I pull a 36foot 3horse slant at times and running at those RPM I still see a 1-2 mpg increase, but its just where my engine likes to run the best and most efficient at. So is running slower better for everyone?

My Dually maintains around 12-14mpg pulling the horse trailer running around 1900, but thats where it has ran its whole life.

Loaded with 2 horses both trucks are between 27-30k total weight.
 

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Mopar1973Man.Com
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I got a suggestion... Get a ScanGauge II and you can measure real time MPG values and see what speed gives the best MPG...



It worth it... Go to...
Better MPG's

and...

ScanGauge II
 

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It runs off the computer correct? Does it go by my gauge as telling it how much fuel has been used or do our trucks have a meter somewhere to be more precise? I understand you calibrate it, but the way it looks by your pictures the less Rpm you run the better your mpg, so is it just figureing it by Rpm and what you calibrate it at for fuel usage? Or does it actually watch how much fuel goes into the engine while your driving up and down hills?

It seems like a pretty Nifty tool, specially if its more accurate than our Lieometers, which my truck does not have. I'll read up on it more and see if I better understand all of its futures.

Here are some of my specs. I noticed an increase in mpg going from 3.5 Stock Straight Pipe to the 5in Straight i have now.
2001 Cummins Auto 3.55 4x4 4in lift 2 door long bed Edge/Att Setting 3/5 K&N Intake 5in Straight
 

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Mopar1973Man.Com
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It runs off the computer correct?

Yes it runs off the information given by both the PCM and ECM computers...

Does it go by my gauge as telling it how much fuel has been used or do our trucks have a meter somewhere to be more precise?

No... It doesn't use the fuel gauge at all but it does have a very accurate fuel gauge built into it that is all calculated by fuel usage. I used it for nearly 6 months since my fuel gauge was dead. I never ran out of fuel using it and every time I fill up and calibrated it it was extremely close like +/- 0.2 Gallons...

I understand you calibrate it, but the way it looks by your pictures the less Rpm you run the better your mpg, so is it just figuring it by Rpm and what you calibrate it at for fuel usage?

You got to calibrate the GPH and the speedometer on board. Other than that the calculations are way off.. Like my stock speedometer is 0.5 MPH off and the GPH is off by 9.6% with my Edge comp running.

Here is the math it uses...

Mile Per Gallon Calucation
Speed (Miles Per Hour) / Fuel Usage (Gallons Per Hour) = Miles Per Gallon

Gallons Per Hour Calculation
Speed (Miles Per Hour) / Miles Per Gallon = Fuel Usage (Gallons Per Hour)

Speed Calculation
Fuel Usage (Gallons Per Hour) x Miles Per Gallon = Speed (Miles Per Hour)

Or does it actually watch how much fuel goes into the engine while your driving up and down hills?

Yes.. It can see the VP44 turn on and off... It can see exactly how much fuel is flowing out of it...

It seems like a pretty Nifty tool, specially if its more accurate than our Lieometers, which my truck does not have. I'll read up on it more and see if I better understand all of its futures.

Here are some of my specs. I noticed an increase in mpg going from 3.5 Stock Straight Pipe to the 5in Straight i have now.
2001 Cummins Auto 3.55 4x4 4in lift 2 door long bed Edge/Att Setting 3/5 K&N Intake 5in Straight
Comments in blue...

Ok here is a video for ya...

My last summer trip...
YouTube - Kellogg, ID to Missoula, MT to New Meadows, ID

Here is the write up...
Better MPG's

Then here is the SG II write up...
ScanGauge II
 

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i towed a 4200lb car on 2150ish lb trailer from WI threw chicago to kalamzoo, mi and got almost 15 going 65 with 3.54 gears
 

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Hey Joe Howard

Another thought 3.54 or 4.10 Rearend? I think its as Mopar1973Man says it, it varies on driving and wind but also the truck. Some trucks like mine will have better milage at higher speeds due to their "sweet" spot being there but others will vary by driving style and daily usage.

Another question I have, how much of a difference will a Auto vs. Manual make? Will having an aftermarket Auto increase my milage considerably or moderatly? Will a Manual not be capable of better milage if you have a clutch that will not slip like stock?
 

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I tow a 39' toyhauler weighing about 13K through NV. At 55 mph at 2200 rpm I get 9. At 85 mph at 2000ish rpm I get 8. At 70 mph I get 8.5. I have tried running 32" tires with my 3.55 gears and I've run 35" tires. Both give me the same MPG, but the smaller tires give me more power in the hills.

For a comparison, my friend has a Volvo semi, pulling 80K lbs in the same weather, same roads, same speeds, he gets 9 mpg loaded.

WTF is up with these engines? I'm pretty sure he has me by at least 100 horsepower, and I know he pushes more wind than I do.
 

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WILLD420:

I pull my 34' and get between 9-11. I don't know tried lots of different things, wish I did know.
 

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most of the OTR engines done turn past 3k RPM and they have multispeed trannies. the new trucks dont get as good as the older ones either due to emissions compents
 

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Towing our 8400 lb camper i average 14-14.5 at 60. Pulling into a good head wind i might lose 5 mpg or more depending on terain and wind speed. Some tips i have learned are. 1. check your tire pressure and adust it to fit your towing load. 2. Let your truck come up to speed gradualy. 3. Keep your boot out of the throttle your gonna lose speed pulling hills anyway why burn more fuel, so plan on the four ways and enjoy the scenery.
 

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2900 mile round trip from Wisconsin to Ft Stockton, Tx and back loaded 21000 gross(pulling goose) down - empty(goose) back. 15.7 for the round. Off of receipts and recorded GPS miles.
 

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i averaged around 12mpg doing average of 75mph towing a 24 foot box with a 3000lb car in it going from ct to nh and back.
 

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Cummins has a site somewhere that talks about the fuel mileage drops after 55mph. It a pretty dramatic drop. Keeping it around 55 seems to be the best balance between mileage and trip time.
 

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Pulling a 3000lb car on a 20' open steel trailer with the a/c on and cc set at 75mph I averaged 18mpg... I run the edge on level 3X1 and let her roll..
 

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9-11 mpg flat ground or mountain pass GCVW 26000. Driving 55 is not easy for me, I get bored.
Now with the 3.55 rear end and 265s not sure what my fianl gear ratio is but 55mph is somewhere around 1900rpm in 3rd gear or are you guys lugging around in 4th at 55?
My truck stays cooler when between 18-23 hundred rpm anywhere outside and it starts to heat up a bit. not hot enough to burn things up i'd hope but I have never kept it there long enough to find out.

Thanks for the great articles mopar man
I dont have the scangauge but next time I tow will be tucson to albuquerque and I will watch my egts and compare them to my mileage from gals added to top off and miles driven on that tank
 
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