Fuel Economy

[Tithy242]

This may be a topic for one of the many diesel truck forums but since a large number of you drive heavy duty diesel trucks and pull 5th Wheel RVs, I thought this to be the best target audience.

On a 540 mile round trip last weekend, I averaged 8.8mpg on the way out and 9.9mpg on the way back while towing. My truck and trailer specs should be detailed at the bottom of this post. Diesel is anywhere between $3.54 and $3.89 where I live and work. Ouch!

I'd like to learn what others have done or are doing to increase fuel economy while towing / not towing. Hear are some of my initial ideas:

1] Lose Weight - (Not me but from my truck and trailer.) Last night I removed the Ranch Hand front guard which weighs in around 140lbs. I also removed my 5th wheel hitch which I had been toting around before. Mine has got to weigh 250lbs. which is why I have left it in the truck and why I must also get it out. I think I've figured out a way to give myself some help.

2] Wind Drag - I've been reading about wind deflectors but am not convinced yet the ones I've seen really help.

3] Diesel Fuel Additives - Anyone?

4] Diesel Tuners / Programmers - I have the Banks Ram-Air CAI so would likely look hard at the Banks Six Gun w/ BanksIQ. My '08 Power Stroke has a DPF which might make the EPA happy but makes me sad during a regen cycle.

On item #4, I thought this group might have real world experience / input doing some of the same kinds of things I do with my truck.

Lastly, I'm all eyes/ears regarding options not mentioned above.

Thank you in advance.

[pineranch]

TC,
Weight reduction is a good start. Just traded my 6.4 for a 6.7 and the fuel milage difference is significant. The 6.4 is a fuel hog and you can spend a fortune getting lets say 2 more miles per gallon.
Mike

[mlh]

You cant get much better fuel mileage but still get a tuner, a Spartan tuner not a Banks. You are ruining your engine with the DPF installed. When it goes in regen it washes the cylinders clean and contaminates your oil with fuel which wears out your engine. When Cummings put a DPF on the Dodge trucks they reduced the service life of the engine by 100,000 miles. First go to the Blackstone Labs web site and get a oil report kit to see what is happening to your engine. Its blackstone-labs.com.

[H. John Kohl]

I just finished a 1060 miles and averaged 10.6 mpg. There was probably 50 miles not towing during that trip.
That calculation is tank fill ups to the top of the neck, not by the generous computer.
I have the Banks tuner. I like it for the extra power and use it. I do not feel it is cost effective for fuel economy.
I did find driving at 55 mph does increase the fuel mileage for my 03. On this trip I drove the speed limit off the interstate and held it between 63 and 65 on the interstate even when the speed was 70. On one trip a few years back I got 8.8 mph running 75 on a 600 mile speed run with a 35 mph head wind.
Cummings has done a study on big trucks and found 55 was the transition from rolling resistance to wind resistance. Every mph over 55 they claimed .1 mpg loss.
Best of luck

[gitrdun]

I drove from San Diego, Ca to Eastern Ky. and back with my 05 Duramx pulling a 2980 running speed limit anywheres from 55 to 75 and averaged 10 mpg I was happy. I have the Banks Ottomind and Banks air filter.

[snfexpress]

We average 50 mph on US highways as we try to stay off the Interstates(we enjoy the scenery and are not in a hurry). Our fuel mileage is usually about 11 mpg. We are heavy with our '09 Big Sky.

One of the ways you can remove your hitch it to hookup to your fifth wheel and then pull the pins holding the hitch to the truck. Raise your 5er which results in raising your hitch as well - now, just drive away leaving your hitch to hang from your king pin.

[richfaa]

We have the 08 F-350,Dually,LB,CC 4:10,6.4. Completly stock. pulling a 06 3400 heavy.Last weigh in was 14,000s. We run 62/65 mph and at the end of any given day will get at least 10MPG. I figure that is not bad pulling all that weight.

[TLightning]

I run just fast enough to get the Allison in 6th gear, which is around 62/63.

[Art-n-Marge]

Me too, like Lightning... my sweet spot when towing is about 61-63 because RPMs are 1800 to 2000, while at 52-55mph they are at 2100 to 2400. Long hauls at the higher speed can get me 12-13 mpg, while the slower speeds will get me from 9-11mpgs.

Other factors are hills, wind or heavy traffic. Getting "stuck" behind a caravan of semis going 45 to 60 will really mess up my mpgs. I typically find a place to pull off for 1/2 hour to 1 hour and hope for a better traffic window. I have been known to catch back up to them once again. You just try to do the best you can.

The wind deflectors don't help as much because at some speeds or wind direction they are sails. It's mostly 50/50 and hence they are not on my list. Let us know how they do for you.

Weight is as low as it's going to get since the rig has already been stripped. I don't travel with what I don't need anyway and don't want to leave home what I just might.

I liked the tuner (Banks six pack) when I had one on another truck, but because of the tuner I drove more aggressive and capable so the mpgs didn't improve that much.

[Trailer Trash 2]

I have added all my last 10 fills and did an average, it came to 12.45 MPG towing and some non towing which was only two times at 14 MPG and 16.2 MPG all the rest were 10, 11,and 12 MPG and those were all towing numbers, I am comfortable with a 12.4 MPG towing average.
Now that was our trip to Colorado from California and towing a 2980RL with all that junk that our wifes can seem to put in them for a trip.LOLOh and going as a few others said 62 to 64 MPH that sweet spot that Art has.

[DQDick]

Mine is stock and will get around 18mph running 55-60 on the interstate. Put the Monty on and it changes drastically. Council Grove to OK, City last night was 11.7mph. OK city to Albuquerque today was only 8.8. Of course it mostly uphill for OK City to Albuquerque and the wind was blowing some.

[Tom S.]

quote:Originally posted by DQDick

Mine is stock and will get around 18mph running 55-60 on the interstate. Put the Monty on and it changes drastically. Council Grove to OK, City last night was 11.7mph. OK city to Albuquerque today was only 8.8. Of course it mostly uphill for OK City to Albuquerque and the wind was blowing some.

You might want to change those MPH's to MPG's!

[RickW]

Your 2 biggest factors on mileage are your driving habits and terrain. In addition some areas of the country sell a winter blend of Diesel fuel in the winter months that will also lower fuel mileage.

You driving habits can have one of the biggest effects. Driving in fairly flat terrain with the cruise set at 57 I can see my mileage climb to 10mpg. But it can fall to the upper 7s if I try to run the speed limit (70~75) when running the hills out west. Because of my driving habits I routinely see a average of 8.5.

[c214dick]

http://www.airtab.com/gallery/rv.html

We installed airtabs about three years ago and have never regretted the decision. Cost was a little over $200 and very easy to install. Mileage increased about 1 mpg and the back end stays much cleaner as mentioned in the above link. My engine was still under warranty and I didn't want to take a chance with a chip. Now that I have 120,000 miles I am looking at a chip as we will be going through the mountains this fall.

[richfaa]

Strange thing about the MPG going down when we hang a anchor of the rear of the truck..Wonder why that happens???

[mlh]

A 3000 pound Toyota Pris will get you 50 MPG a 23,000 pound truck and camper will get you 10 and we complain.
Lynwood

[sreigle]

About 1100 miles recently and averaged 11.2 overall. That's mostly with winterized diesel, which reduces our mileage a little.

TC, the 6.4 is a strong towing engine but it's downside is truly lousy mpg, even when not towing. This is a very common complaint with that engine. And I've been a Ford guy for many years, at least up until we bought this Dodge. Prior two trucks were Ford 6.0L diesels. I honestly don't think you can do much to improve the mileage of that engine very significantly. The best shot would be to slow down. We notice a significant improvement in mileage when towing 60mph as opposed to 68 mph. See if you can find that "sweet spot" where it tows well with minimal downshifting on hills and gets the best mpg. Good luck. I know how frustrating that can be.

[denandannie]

Unlike most, I have a gas engine, Chevy 2001 with an 8.1 liter and a 4.10 final drive 4WD. I get about 8 while towing and 13 w/o the big white monster on the rear. Performance is awesome. I can pass any diesel on the planet. Gas mileage isn't great, but, from what I read here, its not too far off the diesel guys. I'd insert a photo if I could figure out how.

[mlh]

My brother and I have pulled my 2955 with my 7.3, 6. 6.4 tuned and not tuned and his 6.6, 2006 D max. I see no difference in fuel mileage in any of them. The D max is a better pulling machine than the 7.3 or 6. about the same as the stock 6.4 and of course not as good as my tuned 6.4. We also pulled my camper to Wyoming with his gas 454 Chevy DRW. It pulled about like my 7.3 but used a lot more fuel, and ran out of power at high elevations. I don't think there is much difference in fuel mileage in any of the brands. If you run slow enough you get good mileage and if you run the speed limit +5 like I do fuel mileage goes way down. My brothers Dmax is a DRW and mine 6.4 is a SRW with 20 inch wheels. We see no difference in the stability between either truck.
Lynwood

[sreigle]

Well, I really don't want to offend anyone but do want to point out what might not be too obvious from the mpg numbers being tossed around in this thread. So please forgive if anyone is offended by my comments.

I know the difference between 8 and 11.5 mpg doesn't sound like much but when you translate that to the actual fuel costs it's a bit different story. 1000 miles at 8 mpg requires 125 gallons of gasoline. With gas at 3.40 per gallon, that's $425.00. That same 1000 miles at 11.5 mpg (my average towing mileage) requires 87 gallons of diesel. At 3.85 per gallon of diesel, that's $334.95. Gas - 425.00. Diesel - $334.95. Difference - $90.05 less for diesel. Of course, when the price differential or the mpg changes, so do my numbers.

I just wanted to point out that 8 and 11.5 aren't very close unless maybe we're talking two engines using the same type of fuel.