GlennWest Posted November 8, 2017 Report Share Posted November 8, 2017 According to my reading on trucker forum, I have been lugging my truck. They say best mpg and power around 1500 rpms with the 14L. I probably should get an overhead done on it to. 2003 Teton Grand Freedom towed with 2006 Freightliner Century 120 across the beautiful USA welding pipe.https://photos.app.goo.gl/O32ZjgzSzgK7LAyt1 Link to comment Share on other sites More sharing options...
DanBree Posted November 8, 2017 Report Share Posted November 8, 2017 8 minutes ago, GlennWest said: According to my reading on trucker forum, I have been lugging my truck. They say best mpg and power around 1500 rpms with the 14L. I probably should get an overhead done on it to. For my DD15 engine, according to the driver's book, I get the best MPG at 1350rpm and best power at 1450rpm. When I cruise over 1500rpm, my mileage starts to go down again. My fuel log bears that out. Dan & Bree 2010 Freightliner Cascadia 125, DD15, 455hp, UltraShift (Yetti, For Sale) 2015 Grand Design Reflection 308BHTS Travel Trailer (For Sale) Link to comment Share on other sites More sharing options...
GlennWest Posted November 8, 2017 Author Report Share Posted November 8, 2017 Mine states hp and torque crosses at 1550. But I understand the newer trucks are higher hp and less rpms 2003 Teton Grand Freedom towed with 2006 Freightliner Century 120 across the beautiful USA welding pipe.https://photos.app.goo.gl/O32ZjgzSzgK7LAyt1 Link to comment Share on other sites More sharing options...
noteven Posted November 8, 2017 Report Share Posted November 8, 2017 Glenn if it is not downshifting every time it sees a hill coming you are probably good at any rpm from peak torque and up. If you don't have the pedal to the wood mile after mile to maintain speed you aren't "lugging" the engine. It will run happily at low rpm at part throttle with rv gross weight. 1550 is where you want to cruise your truck at gross weights of 100,000lbs and up. This is "too much stuff" in a rv "Are we there yet?" asked no motorcycle rider, ever. Link to comment Share on other sites More sharing options...
Jeff.Sloan Posted November 8, 2017 Report Share Posted November 8, 2017 9.2-9.4 towing; 13.5 bob tailing. Speed for these #s is 62mpg on cruise control Numbers drop considerably if I speed up 2004 Volvo 630, Cummins ISX, Eaton 10 speed (air assist clutch), 3.71 3.07 rear locker, ET jr, 200" WB, GearMaster 2017 Forest River Sierra 372LOK Full time June 2017 DW, 2 kids, and 2 dogs Link to comment Share on other sites More sharing options...
Star Dreamer Posted November 9, 2017 Report Share Posted November 9, 2017 11 hours ago, GlennWest said: According to my reading on trucker forum, I have been lugging my truck. They say best mpg and power around 1500 rpms with the 14L. I probably should get an overhead done on it to. We have the 14l also and pretty similar trucks except ours is a mid roof . Our trailer is probably lighter than yours at 18k # plus our trailer is shorter than the truck. We run at about 63-65 MPH but I do not remember what RPM that is on ours. We go that speed mainly v because of our trailer tires but also just feel it is safer and we are trying to get ready for the slower pace of retirement! Our truck had an overhead done by the previous owner who had converted it to RV use. It had 450k miles on it when we bought it. We get 7.5-9 MPG pulling the trailer but that is mainly dependent on a couple of items: Headwind and how much. This can really suck the fuel. How much stop and go traffic we are in, this also reduces the MPG. I now try to watch my routes to stay on expressways when i can but I love taking back roads. What type of fuel we have. When we lived up north and they went to the winter blend our fuel mileage dropped off and would improve once we got far enough south to fill the tanks with non-blended fuel. You probably wont have this issue down south but if your work takes you up north... Dave 2005 Freightliner Century S/T, Singled, Air ride ET Jr. hitch 2019 46'+ Dune Sport Man Cave custom 5th wheel toy hauler Owner of the 1978 Custom Van "Star Dreamer" which might be seen at a local car show near you! Check out http://www.hhrvresource.com/ for much more info on HDT's. Link to comment Share on other sites More sharing options...
GlennWest Posted November 9, 2017 Author Report Share Posted November 9, 2017 I was researching trying to see if I can a little better mpg. Just knowing I get less than others leads me to think something off. My driving or tight valves. In 55 zones I do need to get in 9th. 2003 Teton Grand Freedom towed with 2006 Freightliner Century 120 across the beautiful USA welding pipe.https://photos.app.goo.gl/O32ZjgzSzgK7LAyt1 Link to comment Share on other sites More sharing options...
Raquel Posted November 9, 2017 Report Share Posted November 9, 2017 Glenn, we have a Cummins in our 2005 Volvo 780, pushing 500hp through an UltraShift. Our 2-year mileage average is 9.8mpg. That's uphill/downhill, headwinds/crosswinds/tailwinds, in town/freeway, grocery shopping/cruising. We keep the speed down to 58-59 when towing because of 65mph rated trailer tires. Besides, what do we have to rush around for? Trish & Raquel -------- "Road Runner" -- 2005 Volvo VNL780, 500hp Cummins ISX, Ultra-Shift, ET-Hitch, 198" wb "Wile E." -- 2013 Heartland Landmark San Antonio Link to comment Share on other sites More sharing options...
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