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What gear to tow in.

Higher gear / lower vacuum or Lower gear / higher vacuum

What gear to tow in.

Postby buzzard616 [OP] » Mar 15 2014, 4:38pm

I pull a 30' TT ( 8,000 lb ) with a 2008 2500 HD 6.0L and 6 speed transmision.
Assuming level ground and no head/tail wind; tow speed 100k / 60 mph ... which of these setups should get more miles per tankful?

Tow/haul and cruise off in M5; turning approx 2250 rpm just on the verge of downshifting to 4th (low vaccum); or

Tow/haul and cruise on in M5; engine will spend most of the time in 4th at 3000 rpm (high vacuum) almost ready to upshift.

I'm not whining about the cost of fuel but when traveling with a group of mostly oil burners and motorhomes with fuel tanks from a train, it can be hard to keep up.


Stu
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Re: What gear to tow in.

Postby allterrainjoe » Mar 15 2014, 4:48pm

For me towing our travel trailer ( about 5500lbs ) with a 1500 the best mileage I see is in "D" with tow haul and cruise on and set to 59 mph. Avg. 11 mpg.... :) You just have to find your sweet spot .......
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Re: What gear to tow in.

Postby esox07 » Mar 15 2014, 4:53pm

That is a pretty good load that you are pulling and I am sure you realize the fuel mileage is going to suck no matter what. It also looks like you have your towing configuration pretty narrowed down already. I guess what I would do is tow one way for the first tank, then tow the other way for the second tank and see which one does the best for you. I dont think it is going to matter either way more than 25 or so miles on a tank anyway. Just blame it on the wife having a small bladder.
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Re: What gear to tow in.

Postby adam86107 » Mar 15 2014, 5:58pm

allterrainjoe wrote:For me towing our travel trailer ( about 5500lbs ) with a 1500 the best mileage I see is in "D" with tow haul and cruise on and set to 59 mph. Avg. 11 mpg.... :) You just have to find your sweet spot .......


haha 59? Can't make that extra 1 mph?
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Re: What gear to tow in.

Postby CKNSLS » Mar 15 2014, 6:06pm

Your not going to get any economy towing.....

There are too many variables to say one gear is better than the other. The electronic transmission will do what it needs to do.

One way will always have a little more wind resistance.


There is nothing cheap about RVing....nothing.
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Re: What gear to tow in.

Postby goraman » Mar 15 2014, 6:28pm

Back in the 70's the 360 Fords got such bad fuel mileage it needed 2 gas tanks. 40 gallons total. You could add another fuel tan k with an aux switch.
Then you won't have to stop as much.
That stupid 360 got 6 to 8 when towing and not more than 12 on the freeway with no load on it at all and was truly gutless the 4.8 has more umph and gets far better economy. The 390 from the mid 60's was another animal all together and one of fords better motors. The inline 300 L6 is still Fords best motor ever.
What motor are you running a 6.0?
If so some Doug Thorley headers will open that block up and get you 1 or 2 more mpg. along with a good flowmaster muffler.
It will also reduce under hood temps and they don't warp and break bolts like the factory cast iron manifolds so it's a win win.
Did mine and got 43 more miles per tank and I have the 4.8 so you could and should do far better especially when towing .
I know you are but what am I?
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Re: What gear to tow in.

Postby GTX63 » Mar 16 2014, 12:01pm

"Tow/haul and cruise off in M5; turning approx 2250 rpm just on the verge of downshifting to 4th (low vaccum)"

Since you already gave the options I'll stick to yours. While cruise control is a nice way to give your right foot a rest during long trips, I have found over the years that gas mileage will drop verses turning it off. While it will do a good job of holding speed, I tend to let speed increase when go down grades and use just enough pedal to maintain or slightly lose speed when going uphill. CC will downshift a lot, and hold speed when you dont need it too. I find it makes about a mpg difference. 5th gear with the lowest rpm shorting of lugging the motor works for me.
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Re: What gear to tow in.

Postby krausee » Jan 28 2015, 6:21am

buzzard616 wrote:I pull a 30' TT ( 8,000 lb ) with a 2008 2500 HD 6.0L and 6 speed transmision.
Assuming level ground and no head/tail wind; tow speed 100k / 60 mph ... which of these setups should get more miles per tankful?

Tow/haul and cruise off in M5; turning approx 2250 rpm just on the verge of downshifting to 4th (low vaccum); or

Tow/haul and cruise on in M5; engine will spend most of the time in 4th at 3000 rpm (high vacuum) almost ready to upshift.

I'm not whining about the cost of fuel but when traveling with a group of mostly oil burners and motorhomes with fuel tanks from a train, it can be hard to keep up.


Stu



my three cents... drop it in 5th and tow/haul on with cruise control off.. 2250 - 2300 is a great RPM for the engine. Cruise control and a heavy trailer will only get you in trouble. My three cents.
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Re: What gear to tow in.

Postby CKNSLS » Jan 28 2015, 8:18pm

My trailer is not quite as heavy at 5,000 pounds, but I pulled 600 miles from Las Vegas to Salt Lake City this past weekend. I pulled at 60mph with the cruise control and tow haul mode engaged. The truck did exactly what it was supposed to do coming down two 6,000 foot passes. The cruise control and tow haul worked together and downshifted the transmission to keep it at 60mph down the passes.

That's what the engineers who designed these trucks programed them to do.

Of course, this trip was in addition to my 5,000 miles trip around the USA towing my trailer two years ago.

And for all those who are wondering-yes the AFM will engage going down a hill when towing.
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