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Long Ride, Bad Feul Economy

pm26

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pm26 Senior Enthusiast

pm26

Posted
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I drove my truck over 900 miles yesterday. I pulled a 5X9 open U haul trailer with a ramp. Empty to South Carolina from Central Florida, then back loaded with a motorcycle. It was incredibly windy, icy wind was blowing like crazy and apparently the trailer's tailgate acted like a sail - I figured I got only about 12 MPG pulling that trailer at 75 MPH, a little better coming back because the wind had died down somewhat. Also, pulling a loaded trailer was a lot better because the trailer never bounced as much as when towed empty. On the plus side, there was not one bug or fly anywhere on the front of my truck. After driving 900+ miles? Seems incredible. Insects surely do not like cold weather, especially cold wind.

 

Still I am amazed how high winds can kill your fuel economy. Under normal conditions, without a trailer I get around 18 MPG cruising at 75 MPH, and that is with A/C on. My A/C was off during the whole trip yesterday.

Zembonez Senior Enthusiast

Zembonez

Posted
Posted

Even an open lowboy trailer will kill your mileage because it acts like an aerodynamic parachute. The flow of air behind the truck is as important as it is on the front - drag wise.

sc4808 Enthusiast

sc4808

Posted
Posted

I pulled my 31' travel trailer from Charleston SC to Moses Lake Washington (2800 miles) a couple of months ago and averaged 8 to 10.5 MPG depending on the terrain and speed. Took lots of $$$$$

 

This Pic was from Moab Utah

 

HPIM0528.jpg

music Senior Enthusiast

music

Posted
Posted

Also... speed is a killer when towing. Towing a 7k lb (loaded) camper that is a huge wind sail, I still manage 10 to 11 mpg if I keep to 65 and slower. Into a headwind, it drops with wind speed so you have to slow down more, but does equally better w/ a tailwind.

pm26 Senior Enthusiast

pm26

Posted
  • Author
Posted
I pulled my 31' travel trailer from Charleston SC to Moses Lake Washington (2800 miles) a couple of months ago and averaged 8 to 10.5 MPG depending on the terrain and speed. Took lots of $$$$$

 

This Pic was from Moab Utah

 

HPIM0528.jpg

 

It's good the know that this truck is capable of pulling a travel trailer this large. Id not think I would dare pull anything that heavy with mine that far. My truck is practically identical to yours, except it is a GMT800, without the AFM. The same engine, Z71, gear ratio, body style.

 

Did you pull the trailer in 3rd gear?

brainpause Enthusiast

brainpause

Posted
Posted
I pulled my 31' travel trailer from Charleston SC to Moses Lake Washington (2800 miles) a couple of months ago and averaged 8 to 10.5 MPG depending on the terrain and speed. Took lots of $$$$$

 

This Pic was from Moab Utah

 

HPIM0528.jpg

 

It's good the know that this truck is capable of pulling a travel trailer this large. Id not think I would dare pull anything that heavy with mine that far. My truck is practically identical to yours, except it is a GMT800, without the AFM. The same engine, Z71, gear ratio, body style.

 

Did you pull the trailer in 3rd gear?

 

 

I remember your thread about rout possibilities.

 

You were kinda gutsy pulling it that far. Our trucks, if they were same model year, would have same tow rating despite my 3.42's. I tow a 5500# TT (hybrid) and wish I had 4.10's.

 

That said, I've learned to just be patient, tow in 3rd, watch trans temps, and I'll get there.

 

Do you have trans/engine temp monitors? what did you see?

 

Larry

2005LT Enthusiast

2005LT

Posted
Posted

Yup, colder weather + high winds + trailer will definitely have a major effect on fuel economy. Even just the cold weather seems to hamper my fuel economy driving around empty. I'm trying to figure out if it's the intake air temp that has the most effect. I realize 'cooler' temps improve power and efficiency with the density of oxygen increasing but at some point when it gets cold that must start to take away from efficiency.

brainpause Enthusiast

brainpause

Posted
Posted
Yup, colder weather + high winds + trailer will definitely have a major effect on fuel economy. Even just the cold weather seems to hamper my fuel economy driving around empty. I'm trying to figure out if it's the intake air temp that has the most effect. I realize 'cooler' temps improve power and efficiency with the density of oxygen increasing but at some point when it gets cold that must start to take away from efficiency.

 

I think that has to do with how long it takes the engine to heat up. Theoretically, if your engine was already heated to operating temp regardless of ambient temp, it would seem to me that gas mileage would be better in cooler ambient temps.

 

Here in the south, where very humid 90's-100's are not uncommon, I can tell that the truck is working harder on those days.

 

Larry

sc4808 Enthusiast

sc4808

Posted
Posted
I pulled my 31' travel trailer from Charleston SC to Moses Lake Washington (2800 miles) a couple of months ago and averaged 8 to 10.5 MPG depending on the terrain and speed. Took lots of $$$$$

 

This Pic was from Moab Utah

 

HPIM0528.jpg

 

It's good the know that this truck is capable of pulling a travel trailer this large. Id not think I would dare pull anything that heavy with mine that far. My truck is practically identical to yours, except it is a GMT800, without the AFM. The same engine, Z71, gear ratio, body style.

 

Did you pull the trailer in 3rd gear?

 

 

I remember your thread about rout possibilities.

 

You were kinda gutsy pulling it that far. Our trucks, if they were same model year, would have same tow rating despite my 3.42's. I tow a 5500# TT (hybrid) and wish I had 4.10's.

 

That said, I've learned to just be patient, tow in 3rd, watch trans temps, and I'll get there.

 

Do you have trans/engine temp monitors? what did you see?

 

Larry

 

 

Yeah, 3rd most of the way, on good flat ground or slight downgrade I would switch to 4th (OD) but I would not allow the transmission to "hunt" between gears, if it started that I would just drop back down to 3rd and she was happy.

 

I ran between 65 to 70 MPH on the Interstate and the truck did great, remember that this was at Thanksgiving and the Temps were pretty low for the entire trip, my Transmission temp never got above 190 even on the longest grades.

 

The only thing I plan on changing before the trip back in July is to put some LT tires on (D or E Rated), right now it still has the stock P rated Bridgestones and I had a little more sidewall movement than I care for, I think the stiffer tires will remedy that. My 03 is actually a little more stable at 70 MPH with this same trailer than my 08 but the 03 has D rated LT tires so I hope that will be the cure.

 

Overall the truck did better than I could have asked for, I was worried about all of the mountains that I had to cross but even on the longest grades the 5.3L kept me at 50MPH (once or twice down to 45)

brainpause Enthusiast

brainpause

Posted
Posted

<open can of worms>

I didn't like the OEM Bridgestone Duelers. They wore out prematurely, too.

 

I now have E-rated BFG Rugged Trails, and believe this has helped as much as anything I've done for trailer sway. They were great in the ice and snow this year.

 

<close can of worms>

 

I want to buy a ProPride Hitch. Never would see trailer sway again. http://www.propridehitch.com

 

Larry

nickvrebel Senior Enthusiast

nickvrebel

Posted
Posted
Yup, colder weather + high winds + trailer will definitely have a major effect on fuel economy. Even just the cold weather seems to hamper my fuel economy driving around empty. I'm trying to figure out if it's the intake air temp that has the most effect. I realize 'cooler' temps improve power and efficiency with the density of oxygen increasing but at some point when it gets cold that must start to take away from efficiency.

 

you "cold" problem is probably "winter formula" gas related

pm26 Senior Enthusiast

pm26

Posted
  • Author
Posted
You're definitely right there. The "winter gas" also chips away at the economy.

 

Especially when all you can get is the #$%^@ 10% ethanol concoction. :shakehead:

Denali_Joe Enthusiast

Denali_Joe

Posted
Posted

Yeah, the cold weather kills mpgs. You figure the air is denser, so you have to plow through that denser air + crappy winter gas + wind + a frozen stiff truck that has to warm up to get to maximum efficiency. I got my 08 SD now about a month ago and I cannot crack 14mpg yet. Even been taking it easy on the accelerator and doing about 60% highway.

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