Looking at a 2012 F350 DRW 3.73 limited slip CC FX4. I'm averaging 9.3 mpg towing a 13K 5er with a 6.4. How much better mpg could I expect with the '12.

 

A friend of mine has a 2011 6.7L that is getting around 13-14 pulling his very large travel trailer. He has the SRW though.

 

I moved your post - hopefully it should help you get some good answers

 

I have a SRW so I'm speaking in general terms and not specific to a dually truck.

I have owned a 7.3L two 6.0L and now a 2011 6.7L
I a not seeing any better fuel mileage when I tow. I do see MUCH better mileage running empty.

I tow a 4H GN horse trailer that weighs around 13,000lbs, a 7'x'14' dump trailer that is often 12,000-14,000lbs with gravel or broken concrete, an enquipment trailer with a skid loader mini excavator loaded on it which is probably in the 11,000 to 12,000lbs range. And I get 11-12 mpg around town and 12.5-13.0 mpg with hiway driving. Which is very consistent to what I got pulling those same trailers with my 2006 6.0L truck. I skipped the 2008-2010 6.4L and most folks I talked to admited they got worst mileage with that engine than my 6.0L did. So I would expect a slight improvment over your 6.4L pulling the same trailer.

Now empty is another story, My 2011 6.7L gets better mileage when being driven empty that my 6.0L ever did. I attribute that to the 6sp tranny vs a 5speed and the higher rear end ratio. If you can get these trucks into 6th gear and loaf along at 1500-1600 rpm you will get better fuel mileage vs running at 2000 rpm in the 6.0L engine.

Fuel mileage aside, The new 6.7L engine does pull the loads better than the older 6.0L engine did. But again I can't speak for comparing the 6.4L

 

I wish I got 13-14 pulling my very large TT. I'm getting about 10.4 in Florida on Interstate at 62mph with cruise on. I have the SRW.

 

Hmm...that is rather interesting. It's not like this guy baby's the truck either

 

I have a 2011 F 250 SD SRW I get 9.5 - 11.0 pulling my 5 er its 14900 Dry. Cruise set at 65 mph I live in Wi.

 

It appears towing heavy trailers you need a rear end gear which would put you on the torque curve at 1700 - 2200 RPM in 6th gear. Especially towing out West, where everything is either WAY up or WAY down! I think my gut choice of a 3:73 rear end might turn out to be the right choice for a dually.

If I can get a 2 to 3 MPG increase towing over the 6.4, assigning a cost per gallon of $4.25 and driving 20,000 miles, the savings at the pump works out in the neighborhood of $4000. Which ain't chump change!

 

Chief,

Hi, I pull an 18K 5er that is high profile and 8 1/2 feet wide and 40 feet long. I regularly cruise down the Interstates at 75-80 mph. On the two lane roads, I run 65-70 mph. My truck is a DRW F-350 with the 3:73's. It pulls it like a dream. At 75 mph, according to the speedo which at 75, is 2 mile per hour off, I'm rappin 2100 rpm. So when I say 75 mph, I'm set at 77-78 on the cruise. Now the not quite as good news: at 75-80 mph, I run 8.7 mpg. That is pretty consistent. At 65 mph, I can get 9.1 mpg. At 60 mph, I can get 9.5ish. I just completed a 4400 mile trip with the 5er, and I averaged 8.8. That was a mix of Interstates and two lanes. A lot of hills and two lane between me and Moab, UT and back. A lot of Interstate between me and Rochester, MN and back. Also threw in a trip to southern MO for good measure.

Very happy with the truck. I came from an '07 Duramax/Allison. That was a nice combo. I'm getting more and more used to the 6.7 and the six speed. I'm going to say they are pretty close to the same setup. Pulling power on the 6.7 is awesome from 1700-2200 rpm, in my opinion. Does it loose speed on hills? DUH. They all do. Does it crest the hill sounding like a jet airliner when the aux fans kick in? Not very often. Nothing like my D/A did. There are going to be some differences from what you are used to, but I think you will be pleased with your swap.

I have never driven a Dodge other than a test drive. I have never driven the 7.3, 6.0, or the 6.4. Only the Dury diesel. I can't tell you what you will get other than noticed and sore cheek muscles from grinning.

 

Right now after 20 K miles, I'm seeing 9.3 MPG average towing, with a CGVW of 23000# (I put in on the scales). Our last trip between Lancaster, CA and Mammoth Mountain, CA, round trip, with a constant climb northbound, including Sherwin Grade north of Bishop, using the cruise control set at 60 mph/2000 RPM except on Sherwin Grade. And kept max air conditioning on, the entire trip. To keep 60 it downshifted 2 gears and was running at 3200 RPM at over 6000' elevation to the summit is typical of our trips. A 6.4 isn't a slouch in the power department. But don't go over 60 or under 57, MPG sucks on the flats running very much over or under 2000 RPM towing my trailer.

I'm looking at getting at least a 2 or 3 MPG increase if I go with a 6.7. Given the difference in our trailers (13K and 18K), and both being high profile trailers, my goal might be achievable with a 3:73 gear ratio. And, in CA, even the truckers go 60.

Thanks, Jeff

 

You might increase by 2 mpg, I did on all my trailers as compared to the 6.4.

I liked the power my 6.4 had but this new motor is really a totally different experience. Even if you only gain 1 mpg, you will enjoy the truck.

I do want to throw in a kink though, if you can get a 3.55 in a dually (may not I don't remember) you might consider it. The 6 speed trans is nice and with the manual push button mode you can control your power output and rpm range very effectively. Mine cruises best at 1700 or so rpm which is right around 70 mph. I like to cruise interstate at 72-74. I average around 10 mpg with my 12-13k fiver. Never pulled it with the 6.4 I had but mpg values in the 8-9 range were pretty normal.

 

Pulling my #7200 empty (#9000 loaded) 5th wheel on a 3200 mile trip, I averaged 11.5 to 12.0.

Empty I get 19 to 20. 20 is more closer to the 60mph. I usually drive 70,

--
Gordon

 

It seems Ford doesn't have a 2012 brochure yet, but the 2011 one only shows 3:73 gears for both the 2X4 and 4X4 DRW F350. With the tranny having 2 overdrive gears though, I guess one or the other should keep the RPM and boost in the correct range for best MPG at my 60 - 65 mph tow speed, somewhere around 1700 RPM from the posts.

Thanks!

Now if Washington DC would just get this budget battle done, I'd pull the trigger on this. I'm Retired USN, so one of my paychecks is on the line right now.

 

I posted this in Feb. I repost cause the numbers are still accurate.

I recently completed a 10 week trip with my truck and 5th wheel trailer and want to share the fuel mileage numbers.
First the truck: 2011 F350 6.7L PSD CC KR FX4 DRW. The truck weighs 8970# on the truck scales.
The RV is a 36 ft, triple slide, Avion Savannah 5th wheel. The RV weighs 15740# on the truck scales.
The numbers:
The total miles on the truck are 11550.
The total miles towing the trailer are 5105.
The calculated fuel mileages are:
City w/o the trailer – 14.00 mpg
Highway w/o the trailer (70 - 75 mph) – 16.24 mpg
Towing the trailer on mostly interstate (62 - 64 mph) – 9.78 mpg

Bob in Houston

 

Considering the weight differences and the speed variations, those are pretty close numbers to what I posted above. Glad to see we're comparable in numbers.