2018 RV-Dreams Spring Educational Rally - April 23 -29, 2018 in Pahrump, Nevada
Spots Still Available!! Click Here To Get More Information & To Register


Members Login
Username 
 
Password 
    Remember Me  
Post Info TOPIC: TFL HD MPG Loop


RV-Dreams Family Member

Status: Offline
Posts: 53
Date:
TFL HD MPG Loop


The last couple years the TFL guys do a towing MPG loop .... very interesting.  Here is the HD video ....

https://youtu.be/274hcMblOQU

I would have to say I was a bit surprised at how low they were.  I am seeing around 10 no wind & no hill days and as low as 8.5  with headwinds & hills (GCVW ~29k).

Andy



__________________


RV-Dreams Family Member

Status: Offline
Posts: 1565
Date:

The MPG numbers don't surprise me... 23,000 lbs at 70MPH the trailer is not aerodynamic at all... so not quite typical of most RV applications. Slow down to 62MPH and tow perhaps 5000 lbs less would yield far better MPG numbers.

Even that test shows GM the clear winner financially even though it's MPG was lower than RAM. The difference of only 0.2MPG amounts to less than 220 dollars per year with 20k miles driven (@ roughly $2.40/gal). Traded off against a 10,000 dollar lower sticker price makes it a no-brainer economically speaking. Of course YMMV and personal preference is always in play, and you'd have to compare apples to apples in the option department. Surely there's a Ram equivalent or vice versa for GM and Ford for that matter. It's kinda hard to know if all three were similarly spec'd out option-wise.

JMHO

 



-- Edited by BiggarView on Saturday 11th of March 2017 11:55:36 AM

__________________

Brian, Cindi & Josie (our fur baby)



RV-Dreams Family Member

Status: Offline
Posts: 53
Date:

Good points .... I don't drive faster than 65 .... Would like to hear what Cummins12V98 gets.

Andy

__________________


RV-Dreams Family Member

Status: Offline
Posts: 87
Date:

Last trip to Colorado my 2014 ram diesel averaged 10.5MPG when pulling 5th wheel. Also my trailer weight is only 15k , so I too agree that running in the low 60's really make a difference.
Was glad to see this comparison done, very good information.
Jim

__________________

Jim. KM5J

2014 6.7L Ram 3500, 2008 Excel w 280 watts of solar , 2012 Jack Russel.

Living the dream!



RV-Dreams Family Member

Status: Offline
Posts: 1936
Date:

Obviously once reaching the desired speed the rear end ratio will make a significant difference in MPG ("Ask me how I know this") - But I thought it might be interesting to share some numbers.

I have an old "Estimated Horsepower Required" calculator to move a load (HP at the rear wheels) at different speeds and loads.  The horsepower number is regardless of rear end ratios etc.  Naturally YMMV but the calculations back up what we all know - faster = less MPG - more or less.

These numbers are for flat ground, no head wind. (Tail wind BTW offers no improvement.)  Also this is for turbo charged engines (diesel) which, more or less, negates any impact of altitude all things being equal unless one reaches the turbo's critical altitude.

So, for my rig - at its overall height, ground clearance, combined weight, etc.  Here are the numbers:

At 50 MPH - 124 HP

At 55 MPH - 152 HP

At 60 MPH - 185 HP

At 65 MPH - 223 HP

Here are the same speeds with just a 5 MPH headwind still on level road:

At 50 MPH - 152 HP

At 55 MPH - 185 HP

At 60 MPH - 223 HP

At 65 MPH - 266 HP

More HP requires more fuel regardless of the engine, etc.  So it's pretty clear why we burn more fuel the faster we drive.

Just information, FWIW.  Again, YMMV.

Bill

 

 



__________________

Bill & Linda
2014 New Horizons Majestic F37RLTSS 96

2016 RAM 5500HD \ 4-Wheel Drive \ Link Air Ride
Classy Chassis RV Hauler Bed Conversion \ Aux Fuel Tank 



RV-Dreams Family Member

Status: Offline
Posts: 863
Date:

I also get about 10 mpg towing at 65 on flat ground. Headwinds or hills will move that down to 8.5 or so. You can see from my signature that I have a Ford. Not to come off like a fan boy, but the 2015 F350 (with 3.73 gears and 860 lbs ft of torque) went up the IKE Gauntlet 45 seconds faster than the 2017 F350 (with 4.10 gears and 925 lbs ft of torque). This is a pretty big discrepancy and it makes me wonder if there isn't something going on with this particular test truck. For a newly designed "bigger, badder, better" truck, this one stunk up the place. Slower in every towing test with worse MPG, improved only in downhill control. The only other thing it did well in was the 0-60 unloaded drag race where it beat the other two easily. If this truck really is a healthy truck and this is what Ford brought to the market ... heads should roll because they have succeeded in making the truck worse.  Makes me glad I bought a 2016.

Bill makes a good point, more power requires more fuel.  Just physics, so no mystery there ... except this particular 2017 Ford appears to make less power on more fuel.  Some could be attributed to efficiency issues (parasitic drag, torque converter slip, etc.) but since most of those things are basically the same as 2015, the lower performance (compared to the 2015 Ford) can't be explained by that.

Proves yet again that you should never buy version 1.0 of anything that is new and improved.  Although it seems to have worked out for the Chevy.

-- Edited by RonC on Saturday 11th of March 2017 11:07:57 AM



-- Edited by RonC on Saturday 11th of March 2017 11:12:49 AM



-- Edited by RonC on Saturday 11th of March 2017 11:45:13 AM

__________________

Ron and Janice

 

2016 Ford F350, King Ranch, DRW, 3.73's, 4x4, CC, 6.7 Powerstroke, remote control air lift system

2017 Durango Gold 381REF (41 ft, 5 slides), MORryde IS, 8K Disc brakes, GY G114  LR H Tires, 27,320 lbs CGVW

Full Timers class of 2016



RV-Dreams Family Member

Status: Offline
Posts: 53
Date:

FYI - 2015 Ike trailer was 21.6k lbs. & 2017 Ike trailer was 22.8k lbs. so not exactly the same.

Andy

__________________


RV-Dreams Family Member

Status: Offline
Posts: 863
Date:

Yes, I was aware of the weight difference, but even that shouldn't have accounted for the difference in time (I don't think). For what it's worth, I figured that the change to 4.10 gears and the bump to 925 in torque would have made that weight difference "disappear" and they would have performed about the same, but it wasn't even close. The extra weight does have an effect, no doubt, as the Ram was about 20 seconds slower than the 2015, but the Ford's performance is baffling to me. Can't really bring the Chevy into this as the 2017 Duramax is such a big upgrade from the 2015, there is no fair comparison to the 2015.

 

In fairness, the difference in times is about 15 seconds between the three trucks ... after 7 miles of 6% grade, so very close.  I think Brian said he'd call it a tie, he's probably right, the differences are very small.



-- Edited by RonC on Saturday 11th of March 2017 05:45:01 PM



-- Edited by RonC on Saturday 11th of March 2017 05:45:35 PM

__________________

Ron and Janice

 

2016 Ford F350, King Ranch, DRW, 3.73's, 4x4, CC, 6.7 Powerstroke, remote control air lift system

2017 Durango Gold 381REF (41 ft, 5 slides), MORryde IS, 8K Disc brakes, GY G114  LR H Tires, 27,320 lbs CGVW

Full Timers class of 2016



RV-Dreams Family Member

Status: Offline
Posts: 337
Date:

ahull wrote:

Good points .... I don't drive faster than 65 .... Would like to hear what Cummins12V98 gets.

Andy


 Hi Andy,

 

I have recorded every tank fill since new towing my 23K DRV and 33K combined.  My hand calc AVERAGE good bad and ugly from 7-10.5 is 9.0mpg.  That is turning 1,750 while in 6th at 60mph and having 4.10 gears.  This is West Coast and a trip from CA to IN and back thru the Rockies.  Considering the weight I am very happy!



-- Edited by Cummins12V98 on Sunday 12th of March 2017 06:45:31 PM

__________________

2015 RAM/Cummins/Aisin/4.10's/3500Dually

2016 Mobile Suites 39TKSB3 "Highly Elited"

32,950# combined



RV-Dreams Family Member

Status: Offline
Posts: 455
Date:

I got 5-7mpg with my 2012 Duramax dually towing my Teton at 21k. That is fairly flat road too. Now my Teton is flat nose for sure and very tall. Interesting is my Freightliner gets 7-8 towing it and carrying my SmartCar at 65. If I drop to 60 get 9. 55 is better still but I don't tow that slow. There is a huge sail factor with high 5th wheels. Slower you go the less air drag you get.

__________________

2003 Teton Grand Freedon  2006 Mobile Suites 32TK3 SOLD     2006 Freightliner Century 120 with Detroit 14L singled, ultrashift,  hauling a 2016 Smart Passion



RV-Dreams Family Member

Status: Offline
Posts: 39
Date:

Guess I'll chime in, for what it's worth.  Someone here or on a diesel blog said " torque is power but RPM's use fuel".  With lower gear ratio as in 410, the engine turns faster, using more fuel.

As to speed and fuel, my 6.7 Ford diesel with 3.73s will average 8.5 towing 21K at 70MPH.  Drop it to 60 to 65 mileage goes up to 9.5 to 10MPG.  Problem is I feel like I'll never get anywhere. Its all in the mind. no

 



__________________

2015 Ford Lariat 350 Diesel CC DRW.

2015 Mobile Suite DRV 38PS3 / 39 ft 5th wheel purchased in April from Mellott Brothers in PA.

TrailerSaver - TS3 AirRide Hitch

Gary & Linda



RV-Dreams Family Member

Status: Offline
Posts: 337
Date:

Gary Marcondes wrote:

Guess I'll chime in, for what it's worth.  Someone here or on a diesel blog said " torque is power but RPM's use fuel".  With lower gear ratio as in 410, the engine turns faster, using more fuel.

As to speed and fuel, my 6.7 Ford diesel with 3.73s will average 8.5 towing 21K at 70MPH.  Drop it to 60 to 65 mileage goes up to 9.5 to 10MPG.  Problem is I feel like I'll never get anywhere. Its all in the mind. no

 


 Are your towing numbers hand calc over many tanks and in all conditions?



__________________

2015 RAM/Cummins/Aisin/4.10's/3500Dually

2016 Mobile Suites 39TKSB3 "Highly Elited"

32,950# combined



RV-Dreams Family Member

Status: Offline
Posts: 39
Date:

Yes they are.  I calculate it by tank fillings and mileage between fill ups. And this is over the past two years and over 15K miles of actual trailer towing.

 

Gary



__________________

2015 Ford Lariat 350 Diesel CC DRW.

2015 Mobile Suite DRV 38PS3 / 39 ft 5th wheel purchased in April from Mellott Brothers in PA.

TrailerSaver - TS3 AirRide Hitch

Gary & Linda

Page 1 of 1  sorted by
 
Quick Reply

Please log in to post quick replies.

Tweet this page Post to Digg Post to Del.icio.us