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lomo5202 12-08-2016 09:58 AM

cummins diesel Larry
I have a 2012 Ram 2500 and would like to boost performance and economy. Anyone have a similar vehicle who has made improvement changes?

slowmover 12-09-2016 04:30 PM


There are several CTD owners here. Search posts under Cummins. Also on CF. Search posts under my name.

Here the outline:

MPG is part of vehicle operational cost. Using a journal or phone app, record all miles and all gallons purchased. At the end of a specified period, quarterly or annually, total miles divid d by total gallons will give the important number: the average.

Tank by tank doesn't mean much. Subject to all sorts of error

The trick to reducing fuel consumption is to get the most from each gallon. This is primarily operator mindfulness. The desire to become a better driver.

Modifying the truck from stock configuration isn't the answer (I'm not going to comment on emissions deletes). The truck as delivered new is best.

Reduce the number of annual miles, but get the same things done.
Combine multiple trips into one.
Eliminate idling
Drive so as to never stop
No left turns

Start with records and start by getting the engine hours recorded on the truck. Divided into odometer miles, this will give the average mph. The higher this average, overall, the higher the MPG. Below 27-mph is unacceptable. Cummins rates engine life at 35-mph.

The goal is an increase to the average annual mph and a PERCENTAGE improvement to the annual average MPG

The way to do that is to reduce the annual number of miles while accomplishing the same things AND to drive the remainig miles at a higher level of skill.


Skill enhancement is what you're asking specifically. On different year models things will vary. For best economy I upshift the NV56 in my truck at 15-1600 rpm. I avoid ever getting above 2000 rpm in any scenario. Etc. This means quite a few details to work out so as to never have to stop in city traffic. Different times. Different routes. Different speed most of all.

Same for highway. Aero resistance shoots sharply up at 60-mph. I run 58-mph. I plan any stops in advance. I drive pretty much the same way solo or towing my 35' travel trailer.

Another gauge of keeping money under control is brake and tire life. I average over 100k on those two.

Take it for granted that long life, fuel economy and safety are all on the same page.

Spending money on gizmos, etc may never pay for themselves. Work that out in advance.

Keep records and be willing to establish new habits. 13-weeks of being consistent for a new Pattern.

Lots more here. Much in the how to. Details.

Diesel Dave set some records. Read what he did. But remember the highlighted above. Right attitude and good habits. Don't start something you won't use every day. But push to find out what you will.

lomo5202 12-10-2016 10:54 AM

I do everything you suggest and have for 30 to 40 years. I seldom need brakes, but still only get 12/13 in town unloaded and 14/15 on trips unloaded. Loaded i get about 10/11.

slowmover 12-10-2016 02:16 PM

The switch to DEF engine tuning brought MPG back up on later trucks. Your numbers are what I've read with others. Where did you start on MPG and how much improvement has been made?

I'd fill it at a station 30-miles or so from home out on the Interstate and run it another 100 miles or more round trip back to that same pump. Cruise control at 60-mph. Fill tank both times same way and only to first click off. Consider this baseline Hwy MPG.

Using that highway baseline you should be able to get within 15% in the city. A goal.

Much depends on how far you drive annually as to the effect on the fuel budget. And how long you'll keep the truck.

In my case with a 2WD now at 210,000 I'm not far from having spent less than half from an ordinary owner with a 4WD, auto trans, minor lift and who has had to rebuild front end plus convert to post 2008 steering wheel who's covered the same miles. In other words, I could or have bought and run two trucks. So it's not just MPG in contention.

There are tuners and such that change things. Past legality, will they pay for themselves? Will they short n engine trans life (usually yes). Etc.

Tires are otherwise the big change. Highway rib closed shoulder best. This can be 1.5-2 Mpg to the average.

Others to check are steering slop, from column shaft to wheels, alignment, brake drag and CAC leaks. Weak lift pump.

A bed cover will help. See the half tonneau idea here and consider making one from plywood. Side skirts. Better front air dam. Synthetic fluids.

See post by Big Dave

gumby79 12-10-2016 08:57 PM

Install an EGT and run the absolute lowest temp posable to maintain speed . In my antique(no computer) 91 .5 Cummins I have to run agenst the governor x92.5mph for an hour and then idle it for 3hours to drop my milage in to your naborhood . If Whats broken ?
You have a technology advantage. You should be were my cap puts me . 24+
Adjust your valve lash . Inspect evry thing u-jounts diff, trans , mounts ,brakes . Ect ,ect.
Fill in your garage ...we can help more if we are informed.

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