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dznf0g · 08-30-2011, 10:40 PM

Quote:

Originally Posted by eglisems

Brian,
GREAT looking truck, I will be interested in hearing about your exp. with the camper once installed.
A note on the tires per your previous question.... we tour the country, last year from Key West to Alaska, this year from Cali to Labrador....trust nothing under an E load rating due to the stress on corning and esp. the extra weight in your bed- A strong contender is Michelin's LTX M/S 2's they are rated for 70k miles, and have held the road like no other.
As far as MPG, we avg from 11.6 to 14.2 as a best. there are a few main factors. Weight, Speed, Grad of the road, quick starts, etc. We are pretty conserative though. However believe our numbers shake out with the "norm" found here on the form. One rational we found in going with the DRW, is the lateral force ( we tow a loaded 34' Limited....not afraid to use it ;-)))
Sounds like you are off to a great adventure, mind your speed/inflation ratings on your AS tires. GoodYear is rated at 55mph, whereas Maxxis is rated at 65. Heat, early wear and blowouts occur....if ignored...but that's another thread for another day....enjoy the road in your new rig, it's a beauty....

Where did you find speed ratings for ST tires? It is my understanting that ST tires have no speed rating???????

Elf1 · 08-30-2011, 10:48 PM

Through the Maxxis site, if "someone" could tell me how to include a photo on a post, Id be happy to post it to the tire thread- Regards...

Elf1 · 08-30-2011, 11:06 PM

In the interest of safety, please excuse the "mis post" of the following information regarding Maxxis Tire Loads:
Trailer Load/Inflation Chart
LTX M/S2 | Michelin Tires

dznf0g · 08-30-2011, 11:14 PM

Quote:

Originally Posted by eglisems

In the interest of safety, please excuse the "mis post" of the following information regarding Maxxis Tire Loads:
Trailer Load/Inflation Chart
LTX M/S2 | Michelin Tires

Nice looking rig!

xrvr · 08-31-2011, 05:53 AM

Purman, actually it is, the other posts are off topic as this one is. jim

**moosetags** · 08-31-2011, 06:22 AM

Quote:

Originally Posted by eglisems

In the interest of safety, please excuse the "mis post" of the following information regarding Maxxis Tire Loads:
Trailer Load/Inflation Chart
LTX M/S2 | Michelin Tires

Thanx for the fuel mileage info. I like the matching graphics.

Brian

Elf1 · 08-31-2011, 06:42 PM

Quote:

Originally Posted by zigzagguzzi

Purman, actually it is, the other posts are off topic as this one is. jim

Jim,
Who died and left you in charge....your not, so get over it.... if someone posts a bit off key..thats life, esp if an apology is offered..No one really needs a hall monitor at this age do we??

**moosetags** · 09-02-2011, 07:44 AM

The new truck now has 2400 miles on it. A couple of days ago, we pulled Lucy on a short trip from Jacksonville, Florida to Hardeeville, South Carolina (160 miles) at 70 mph. Fred's fuel mileage was a little less impressive. He averaged 13.1 mpg. We are heading back to Jacksonville today, and we'll see how he does.

Brian

BillTex · 09-02-2011, 07:59 AM

Quote:

Originally Posted by moosetags

The new truck now has 2400 miles on it. A couple of days ago, we pulled Lucy on a short trip from Jacksonville, Florida to Hardeeville, South Carolina (160 miles) at 70 mph. Fred's fuel mileage was a little less impressive. He averaged 13.1 mpg. We are heading back to Jacksonville today, and we'll see how he does.

Brian

Brian, diesels are less sensitive to load than gassers, but are sensitive to RPM. Diesels make peak power at 1800 RPM, peak efficiency on either side of this. When driving the diesel, try to set your speed based on RPM not mph, This will take some experimentation on your part. You have the 6 spd Alli, same as us, some speeds I reach peak efficiency; 59 mph, 63 mph, 67 mph, 69 mph, 73 mph. Depending on where we are, what the load is, etc…I pick one of these speeds and lock the cruise control. All of these speeds leave us right where we should be in the RPM range. I don’t tow any faster than 69 mph, unladed I will drive 73 mph on the freeway if conditions allow…and surprisingly get very good mileage at this speed.
The other variable of course is friction-your “profile” will help determine some of this (kayaks on the roof, bikes, etc).
So try some different RPM (“speeds”) and take some notes.
Keep in mind, your truck is brand new and mileage will improve. I saw some improvements ~15k miles, 25k miles, and recently ~50k miles. We now get 16 mpg towing the AS.
Have fun,
Bill

slowmover · 09-02-2011, 11:23 AM

MPG drops like a rock above 60-mph. Brand, motor, etc are irrelevant. There are no ways to fix this via gearing, etc. The best mpg will always be at or below this speed for highway travel. Second, the vehicle is designed to provide best towing performance between 55 & 62 mph in all aspects (handling, braking, acceleration and fuel economy), again, regardless of brand. I find that a tow speed of 58-mph gives me room to accelerate for the hill ascent, and to drop off in speed some to get a heavy vehicle around me when passing. And very little throttle movement, a key to steady-state highway mpg, when doing either of these.

That D-Max ought, like any other vehicle nowadays, see incremental improvements in FE through 30k miles. For highway travel, though, the cruise control set speed that gives the lowest rise in manifold pressure and exhaust gas temp while maintaining speed up and down unremarkable rises will also be the one that gives best mpg. The sweet spot.

For someone serious about mpg then a search for a BSFC map of the engine will give fuel burn rates versus rpm that allow for the most intelligent choices.

.

xrvr · 09-02-2011, 01:21 PM

The mods are selective from what they consider offtopic---really is a problem on this forum from my experience. So yes I am in charge of my activity here! Good bye. jim

aswbe · 09-02-2011, 04:43 PM

Just returned from my first long trip pulling the AS, 2000 miles. Avg 13.8 towing fill up to fill up, 14+ when mixed with non towing mileage. When I kept it at 63 or lower I hit the 1/4 tank increments like clock work at 100 mile intervals less if above more if below. One long stretch of constuction at 50 avg pushed 14.2 mpg. and 130 miles at 1/4 tank increment. Current mileage on the truck is 48000. I got 11-12 mpg pulling horse trailer from new to 25000 miles. Not sure what that is attributable too... engine break in vs configuration of load.

I met up with another AS identical size pulled by SUV V8- he reported 9 mpg. I calculated using .30 difference in cost per gallon a $240 savings for the trip vs gas. I am happy!

I did not monitor RPM but I will next time. But I do agree that anything above 60 mph decreases fuel economy exponentially when towing.

Anyone use fuel additives? I was told that diesels before '07 needed additives to combat the effects of low sulfur fuel.

**moosetags** · 09-02-2011, 06:22 PM

I made the same trip back to Jacksonville today. I tried keeping it at 65 mph to see if the fuel mileage improved. Today's trip netted a 12.9 mpg average. That's about a 7% mpg reduction than the 70 mph run. I'll start experimenting for Fred's sweet spot.

Thanx for all the tips, guys.

Brian

Lucky Dog · 09-02-2011, 07:32 PM

Here's the sweet spot for my '06 Duramax. I like to tow at about 62-63 mph, conditions permitting, which puts me right about 1700 rpm. Picture taken during a 2200 mile trip this spring as previously described earlier in the thread, towing our 23' Flying Cloud. I agree with BillTex, it varies a little, but this is in the max torque/power band area. With the Alli 6 speed, the Duramax just loafs along; no stress, no strain.

redeagle313 · 09-02-2011, 08:57 PM

Quote:

Originally Posted by dznf0g

nice looking rig!

x2!

redeagle313 · 09-02-2011, 09:02 PM

Quote:

Originally Posted by moosetags

I made the same trip back to Jacksonville today. I tried keeping it at 65 mph to see if the fuel mileage improved. Today's trip netted a 12.9 mpg average. That's about a 7% mpg reduction than the 70 mph run. I'll start experimenting for Fred's sweet spot.

Thanx for all the tips, guys.

Brian

Brian,

You may have had a DEF regen during this trip, and that will hit your mileage.

**moosetags** · 09-02-2011, 10:47 PM

Quote:

Originally Posted by redeagle313

Brian,

You may have had a DEF regen during this trip, and that will hit your mileage.

I have read some about this DEF regen on the Diesel Place Forums, but I don't know if I understand what it is. Could you please explain further?

Thanx, Brian

Sky · 09-03-2011, 08:08 AM

Hi all

I have been pulling a 30 footer with an 2006 DuraMax for 4
years now, and here are my thoughts:

The slightest amount of head or tail wind can make a big
difference in mpg performance. I range between 11 and 16
on flat roads at 60mph. With no wind, I average about 14.5.

Although there seems to be no proof that driving near
your engine's peak torque generates best performance,
from experience I think it does (at least with a diesel engine).
Several truck drivers I have talked to concur. 60mph in
6th gear gets me at peak torque 1600rpm.

Finally, and a little off topic, you got to love that
Allison transmission in tow mode. I hardly ever use the
brakes. Actually, I have towed over the continental divide
on I70 without touching my brakes, amazing.

dznf0g · 09-03-2011, 10:37 AM

Quote:

Originally Posted by moosetags

I have read some about this DEF regen on the Diesel Place Forums, but I don't know if I understand what it is. Could you please explain further?

Thanx, Brian

Don't confuse DEF with DPF.

DPF (diesel particulate filter) is what costs fuel mileage. It is a soot filter, which when gets full), will command extra fuel to be injected late so it burns in the exhaust. This burns the soot into ash which remains in the filter, albeit at a much reduced volume. This cycle is a function of fuel consumed and fuel cleanliness. Approx. every 100,000 miles or so, the filter will need to be removed and the ash dumped out.

DEF (diesel exhaust fluid) has no fuel mileage penalty. It is a fluid (urea based) which is injected into the exhaust stream. It acts as a catalyst to convert NOx into nitrogen and water(?).... I think. Anyway, it takes a pollutant and converts it into inert gasses...

fltlevel510 · 09-03-2011, 11:22 AM

I have a 2005 silverado 3500 with the Duramax and Allison 6 speed transmission and have been getting over 50 mpg while towing. As others have said the secret is RPM. By adding the Eaton 2 speed differential and using a blend of jet fuel, water and acetone it is not uncommon to get these superior results. Additionally, water vapor creates absolutely beautiful contrails behind the airstream. My next mod is to add a duel exhaust system in an attempt to create a dual contrail. My only problem has been towing at speeds over 100mph I get an overtemp warning from my tire pressure monitoring system and stopping distances have increased substantially.

Disclaimer: All data was collected with a vehicle equipped new tires, new brakes, a recent wax job and production test pilot at the controls. Your actual results may vary