Quote:
Originally Posted by slowmover
Welcome!
A "tuner" is not always the answer. Help can be found there, but it is cake icing when you want the recipe for the cake itself.
I want to get better MPG towing a fifth wheel trailer.
I would start with records. Filling out the requested info that others here may see your vehicle specifications would be first (as seen in sidebar). Second are vehicle records. Every gallon and every mile (fuel log). Note also engine hours as average mph is important.
Next is vehicle mechanical (as it has to be done anyway). Rolling efficiency is aided on both vehicles by:
- perfect alignment
- zero brake drag
- proper bearing adjustment
- ideal tire pressure
- wheel/tire balance
and on the TV:
- no steering slop
- fresh fluids & filters
- all book maintenance up-to-date
Even if brand new this is central to "being sure". I also acquire scale tickets as weights are a useful tool for tow rigs. Empty, loaded and separately. Best mechanical baseline.
There are now a good number of discussions of fuel economy for diesel engine pickup trucks around here that are not brand-specific. Strategies and tactics, if you will, that aid best mpg in all situations.
Next, the word "towing" used as a search term will reveal some threads and posts.
The short answer is towing speed. 58-62 mph is about it for "fast" and "good mpg". 55-mph, obviously, is even better.
Skyking has some relevant posts for you (Dodge pulling an Avion 5'er). See also posts by Kamper Bob as his rig is small, but a 5'er, and his ideas are very good reading.
And if you have any pictures of your rig, that is also good if you'd post them.
I believe there are some economy sub-forums on at least one of the Duramax enthusiast forums. But if the Dodge guys are any guide, most all of them think that buying stuff is the answer. Tread carefully as some tuners can shorten component or vehicle life or both. And some replacement parts may not add anything at all, just a bigger hole in the wallet (thus the need for records).
Fuel economy is usually a bunch of small things that add up together to make for improvements. The game is about percentage increases, not absolute numbers. And it is the average mpg through which we can show success.
You may be the first Duramax guy around here. I can't recall another right off the bat (which considering that GM configured truck is the favorite among RV'ers -- just as Dodges are for working trucks and Fords are for riding the wrecker sling -- is a small surprise as RV owners tend to be concerned over FE).
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Thanks! To address some of your points and questions....
I hand calculate every tank, but have never logged the info, other than in my skull. When towing, I find that the wind is the single biggest variable, then speed. I have gotten as low as 7.7 at 60-62 MPH into a stout wind, on winter fuel. I have gotten as high as 13.8 with a tail wind at 55. But the median results are as mentioned in the first post.
As to average speed, on my other vehicles I always end up at about the same number, 38-39 MPH. Obviously on a towing vacation it will be higher. What actionable info does this provide?
My current trailer does not have perfect alignment. I tried to DIY but it needs a spring mount to be repositioned due to factory error. It's not out much but it is beyond spec. I plan to get it done soon when it goes back to the factory for some R&R. I aligned my previous fiver and saw an increase of 1 MPG. With that one I averaged 11.5 at 62. But this current one is also a foot taller, heavier, but more streamlined, so who knows.
Tires, bearings, and brakes are all right on the money, along with TV fluids, filters, maintenance, etc.
There are posts here from 2008 by Randy The Hack who had the same truck as me, and he claimed +3 MPG from a programmer and some typical diesel mods.
I will definitely look at your posts and the others you mentioned. We are open to going to a lower trailer such as an Airstream. I have a sort of goal of a diesel truck and fairly roomy trailer combo that allows 15 MPG. I realize there are many factors involved. But yes, I'm looking for a quick big hammer fix with a tuner will help, safely and painlessly, for a few hundred bucks.
I don't have enough posts to be allowed to include links or photos.