Community Forums

drittal · 02-24-2016, 04:54 PM

I have read of some towing with a gas engine losing MPG going from TT to same length FW. Additional weight and frontal area.

djeirlessr · 02-24-2016, 05:16 PM

I agree with Old-Biscuit. I boated for 26 years and instead of MPG the term GPH is used (gallons per hour). I have been asked how many gallons of fuel my boats used. I tell them I didn't know. I felt if I can't afford the fuel it uses I need to get out of boating.

I sold my boat to buy a FW because DW and I want to travel across country and can't do that with a boat. We towed our FW from Richmond, VA area to North Fort Myers, FL. I averaged 11.061 MPG traveling 61 miles an hour. I think it is due to driving downhill. I'm sure I never got that with any of my boats.

Duane

2016 Crusader 295RST FW
2011 Toyota Tundra iForce 5.7 4.10 gears

Old-Biscuit · 02-24-2016, 11:10 PM

Quote:

Originally Posted by djeirlessr

I agree with Old-Biscuit. I boated for 26 years and instead of MPG the term GPH is used (gallons per hour). I have been asked how many gallons of fuel my boats used. I tell them I didn't know. I felt if I can't afford the fuel it uses I need to get out of boating.

I sold my boat to buy a FW because DW and I want to travel across country and can't do that with a boat. We towed our FW from Richmond, VA area to North Fort Myers, FL. I averaged 11.061 MPG traveling 61 miles an hour. I think it is due to driving downhill. I'm sure I never got that with any of my boats.

Duane

2016 Crusader 295RST FW
2011 Toyota Tundra iForce 5.7 4.10 gears

Back in the 70's just hooking up boat to truck in driveway cost $100

Whitewolf · 03-01-2016, 04:31 PM

I believe that those who said to the effect that if 'dcarver' had to worry about MPG's he shouldn't be RVing, didn't read his posts. His simple question at the end of his first post was "Will there much difference?"

In dcarver's third post he added this; "We make enough money that high fuel costs won't really hinder our travels. I am just really in to getting better mpg."

Nothing in there about not being able to afford to go, just looking for ways to tweak his mileage. Most of us have done it. Towing or not. Especially when fuel hit $4 a gallon.

So lighten up guys. This is the reason some leave forums such as this.

timetogo · 03-02-2016, 10:17 AM

I went from towing 6K to 10K and mileage stayed about the same. Roughly 9 to 11

dcarver · 03-02-2016, 05:24 PM

Thank you to those who understand the question I asked.
About to finish up the last leg of our trip to South Carolina from South Texas and averaging 11.4 with the TT driving between 60-65. Notice much better mileage when the boost stays under 10psi of course lol.
Anyway I asked mainly because in May I'm looking to go to the 5th wheel. Just wondering if I could stay above 10mpg

caissiel · 03-05-2016, 06:51 AM

BbMy experience. We went from a 33ft, 10000 lbs fifth wheel at 10'3" high to a 39ft 15000 lbs and 13'3" high unit and the fuel mileage went from 10 MPG to 12 MPG. Now figure with the same truck towing and same setup.
The advantage of the last unit is simply the frontal design shapped like an egg. The old unit had the strait sloped back front that did not deflect as well. Similar to most cheat TTs. The other advantage is the axles at 7000 lbs compared to 5000 lbs. My tire pressure went from 60 psi to 110 lbs.
I towed boats and travel trailers with my same truck that were worst on fuel then the 39 ft unit. And towed a 5600lbs unit with a V6 gas that was less MPG.
And the V6 was much easier on fuel towing a fifth wheel also.
My experience is that I feel better towing a 40% heavier unit as a 5 th wheel any day then try to pull a much lighter travel trailer loaded to bears.
Besides travel trailers are designed for short trips and low mileage, and would never survive the mileage we put on our units.

For me MPG is a factor that is important for knowing the power required to tow my unit.
I tow my trailers with a program that protects the mess that Ford created with my 6.0 diesel. By keeping the work from 40% to 50% makes a huge difference on the wear and tear on my engine. Although the previous GM 6.5 truck saw 80% to 90% load and 8 psi turbo pressure all the time I no longer need it for good fuel economy..
At 80% torque on my Ford the mileage drops to 4 mpg.
The difference being turbo pressure. So I learn that turbo pressure has great influence on mpg, and programed my truck can operates quit well under 10 psi.

Highway 4x4 · 03-05-2016, 09:42 AM

For MPG only. A 5th is taller, heavier, more side square feet. All that is not going to help MPG. So I think a simple answer would be that the TT will get better MPG. There are many other factors to consider besides that in a RV that could be a deciding factor. If you want to go big, a 5th is the way to go.

lynnmor · 03-05-2016, 12:39 PM

It's hard to get an accurate measurement of MPG. Here is an interesting post about headwind: Headwind vs. Tailwind - Ford Truck Enthusiasts Forums

hone eagle · 03-05-2016, 02:54 PM

Quote:

Originally Posted by Highway 4x4

For MPG only. A 5th is taller, heavier, more side square feet. All that is not going to help MPG. So I think a simple answer would be that the TT will get better MPG. There are many other factors to consider besides that in a RV that could be a deciding factor. If you want to go big, a 5th is the way to go.

And yet every single driver that hauls and delivers both for a living says the same when questioned without hesitation ......

5th gets better mileage.

makes sense if you look at the profile and draw the wind tunnel smoke trails,the 5th combo is a much smoother arc up and over ,the very small (relatively) gap fools the air , the TT combo presents to distinct 'fronts'.
Even that is not as crucial as the flat back of or trailers.
I will paraphrase a aeronautical engineer - pointing at his eye- "this is NOT a gauge"!

caissiel · 03-05-2016, 07:30 PM

The 5th when attached to my truck has about 24 square feet of smooth egg shape area.

Most of the trailers I towed get a 70 square feet of flat angled area at the rear of the truck.
Advantage the fifth anyway. A cap helps but still makes it 2 rear caps to draw energy.

Highway 4x4 · 03-05-2016, 08:33 PM

I guess I should have addad, IMO. I bow to those with first hand knowledge.

gtsum2 · 03-05-2016, 10:09 PM

I asked some transporters who drove for keystone and they all said fifths get better mpg than trailers. I tow 16k and over 5000 miles last year I was right at 10mpg. Some days it was 9, some days 12, other days 7....always seems to average out around 10 though. Wind makes the biggest diff in mpg

marcham · 03-06-2016, 08:53 AM

I can't speak specifically for a 5th but my 1/2 ton with a cap used 10-15% less fuel towing a TT than a 3/4 without a cap, towing the same TT. Drag will be a bigger factor than weight. I have better fuel economy towing in the mountains at 55mph than towing in the flatlands at 65mph. The 5th will be taller but will be closer to the truck and thus will have more aerodynamic airflow.

A tractor trailer can do 6.5-7 mpg pulling 30000lbs.They are much taller and heavier than a TT but have much better airflow.

http://legacy.wbir.com/story/news/lo...-ornl/7177675/