which gear is best for towing??

[seamore]

Heres the deal
2006 3500 single axil Duramax 4wd, extended cab, 8 ft bed, 63000 miles.
Was pulling my toy hauler (heavy) up the fla turnpike and tried a couple of things.
MFG readings from dash panel
numbers approximate but very close

held speed at 55 MPH on cruise

in 4th gear got 15 MPG @ 2200 RPM
in 5th gear got 13.5 MPG @ 1900 RPM
in 6th gear got 11.5 MPG @ 1650 RPM

I like the higher miliage but which is best for the drive train?
Thanks

[FAIRCHASE]

I beleive peak torque is 1600-1700. I am suprised at your MPG.

[Hotdogstand]

I'm personally surprised at such high mileage in 4th and at that RPM.

[DieselLuver]

Hard to believe 15mpg at 2200rpm. Need to hand calculate

[lavarock]

Next time try you test with the tow haul engaged. Your rpms indicate you did not have tow haul engaged and the reason for the lower MPG's in the higher gears. Most likely when you were in 4th the torque converter may have been locked. But in 5 th and 6th it was not.
If it was your 5th gear rpm should have been 1562 and the 6th gear should have been 1342.

[Hook'em_Horns!]

Towin' heavy, higher RPMs, lower gear, less boost, lower EGT.
I show people again and again when we're on cruise and towing big/heavy; come down to 5th from 6th and it bumps from 17xx to 21xx or so and the DIC will just start clicking up by the tenths.

Never have messed around much in 4th, too slow.

[chevor]

I just dont like to listen to all that noise. I like the truck as quite as possible. Personally when I pull I drive with my foot in M mode. Just hold steady on the throttle and downshift before the hills. I usually dont go over 60. It depends on the wind.

[seamore]

Thanks folks, will be towing tommorow and check again, maybe my mpg readout isn't correct

[Blackcloud556]

Originally Posted by Hook'em_Horns!

Towin' heavy, higher RPMs, lower gear, less boost, lower EGT.
I show people again and again when we're on cruise and towing big/heavy; come down to 5th from 6th and it bumps from 17xx to 21xx or so and the DIC will just start clicking up by the tenths.

Never have messed around much in 4th, too slow.

Yep, I like kicking it down a gear to give her some rpms, push some air and reduce egts


Im with everybody else tho. You cant trust the DIC numbers. Also to get accurate numbers you would have to make the same round trip each time.

I made a long road trip to utah and was getting anywhere from 13-21mpg depending on the terrain i was on. So the only way to check accurately what tune changes would do would be the very next day to run the same trip. because even outside temp can change it a lil bit