Anyone ever "de-tuned" a Cummins 5.9 for mileage?

[crazyal]

Unless you need the pickup for towing or the bed for hauling stuff I don't see you saving money. You could easily pick up a crossover used, like the Rav 4, that will give you a little feel of being in something other than a car but still offer close to 30 mpg. Plus if you ever sell it there will still be value. I'm not sure if a detuned Cummings in a Ram will be desirable so you would most likely be returning it to stock. On top of that, at least around here, 30 mpg in a diesel is equal to about 25 mpg once you figure in the extra cost of the diesel fuel. If you want a PU then look into a Ranger or Tacoma 2wd.

 

[Willl]

I'm on my 2nd Cummins 24V. First one was a 2002 2wd, second one is a 2000 4wd. Both 2500's.

They're pretty much 'de-tuned' from the factory. On my first one I also had this big plan to improve MPG.

First move was to help it breathe. Installed a after market intake and a 4" turbo-back exhaust.

That bumped me up about 1.5 MPG.

Second move was a performance chip and that bumped me up another 1.25-1.50.

Right now I'm running about 15-16 town and almost 20 highway. I'd be really surprised to see 25 out of one, even a 2wd.

 

[tractorski]

The answer is not to de-tune it, but to re-tune it. The more efficient you make the motor, the better the mpg. If you make more hp you will(could) get better mpg. The key to this is not pushing down on the skinny pedal. It is hard to have restraint when you could easily break the bake tires loose. If you have that restraint you mpg will go up.

Sent from my iPad using TractorByNet

 

[Willl]

The key to this is not pushing down on the skinny pedal. It is hard to have restraint when you could easily break the bake tires loose. If you have that restraint you mpg will go up.

No doubt.

I actually get better mileage with the chip thingy set on 8 then I do on setting 1. I just got to remember to hold back the reins.

 

[3930dave]

As commented, if you are not towing heavy, gearing the rear end (2wd) really tall is one approach with the 5.9.

I recall researching this a bit, a while back. A guy on a Dodge forum was looking for some crazy tall gearing. Still chuckle over the next threaded comment..... "Whatcha tryin' to do - set a land-speed record ?". :cool2:

Ya never know..... !

Not quite as slick as what Chris was describing here, but most people seem to be pretty happy when they've installed a Gear Vendors splitter. More $$$ than just a rear ring ratio change, but more versatile.

Rgds, D.

 

[Reg]

I still think fuel (dis) economy is much more about HOW you drive than it is about WHAT you drive.

That said, I have always got FANTASTIC mileage out of single cylinder motorcycles, two cylinder have been worse, four cylinder bikes MUCH worse.
Honda had a neat 350 cc four cylinder bike - not just neat, make that SWEET.
But it got much worse gas mileage than my 500 cc single.

If you haven't guessed it yet - I believe there is SOME limit imposed by the number of cylinders (-:
My experiences with 4, 6 and 8 cylinder car & truck engines has been similar, though I have never had a four that had larger displacement than the smallest 8 I have ever had, so can't do that 350 four vs 500 single comparison.

 

[Peacock]

The mechanical Cummins engines are cammed to be most efficient right around 1700 rpm. Any lower or higher than that and you will use more fuel to develop the power needed to maintain your desired speed.

 

[Bladehauler]

For reference , my 2004 Dodge 3500 4x4 SRW auto cummins, which I have added a Banks 4 " exhaust , bighead wastegate, Banks intake , spyntec lockout hubs and a Smarty programmer with the programmer advancing the timing and bumping the power up from 305 hp and 555 tq to about 375.
the truck averages a hand caculated 22.8 mpg if I drive it without my heavy boot.

I am Not a believer in less Hp, but instead in letting a diesel breathe .

Just my .02

 

[firemanmike69]

Keep your exhaust temperature below 600 degrees and the boost below 5 to see your best economy numbers. If you have a performance chip that you can adjust individual parameters on, give it a bunch of timing, if you can't adjust it that way keep it turned 3/4 of the way up and just keep your foot out of it. Get skinny tires and keep them inflated properly. Get a free flowing exhaust and a less restrictive intake.

 

[RobertN]

Mine is an '01 RAM2500CTD xtra/quad cab 4x4, BHAF, 4" exhaust, auto, with 4:10's. I've pulled 19 empty on numerous occasions but I was babying it.

Those 4.10's are killer for mileage, gas or diesel; we rev too high on the highway. With 3.73 or 3.55's mileage would be better. Had a friend who had same truck as mine, except 3.55 and stick; he got 22-23mpg empty.

Have friends with Chevy and Ford; I have never seen them with rosy mileage numbers...

But, as has been mentioned, driver habits make a huge difference...

My truck is a early model 2004, 4.10 gears, a leveling kit, quad cab, 4x4, and the best I've gotten is 17 mpg. I don't think my truck can get 20 mpg.