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

[groundcover]

Years ago I wanted to get Gale Banks to come up with a two injector per cylinder set up. My thinking was it would act like a four barrel on a gas engine. Both fire for get up and go and then just the smaller ones for economy. Now with the high tech computer common rail fuel systems it isn't needed.
I have the Edge cts tuner on my '99 5.9 Cummins it has an economy setting ,biggest thing is to keep your foot out of it. Summer fuel, highway driving she gets 21mpg, 3/4 ton 4x4 srw.

 

[Dmace]

Hey, I'm in Maine, you can't afford the annual (registration) sticker on a new vehicle here! I think that the registration fees "bottom out" as a percentage of new value at 6 years old. These silky smooth roads we have here do not come cheap! :confused3:

Oh I understand, we have a rental property in North Berwick. Taxes should be Maine's motto...

Point being I like the idea of a detuned diesel but think with that large displacement, good fuel mileage just isn't obtainable. A smaller diesel maybe.

 

[Renze]

Less power doesnt automatically mean less fuel consumption.
I dont know if the Dodge version used a different cam than the industrial version (3300rpm vs 2200rpm motors) but your best bet would be an industrial low rpm cam for more torque and fuel efficiency at lower rpm, and a taller rear end to use the low end torque. More rpm means more internal friction, and more pumping losses during intake and exhaust strokes.

 

[ghenges]

I'm to the point where I'm looking for a vehicle that gets (REALLY GETS) 25-30 mpg. I have never owned a car other than my fun car (74 Caddy El Dorado conv.) Been thinking Suburu of Volvo xc70, and used, (4-6 years old).
Now I don't really see myself in a real "car" and some years ago I saw a nice looking Dodge, 4x2 with nice looking wheels, it sat pretty low, with the Cummins. I still have my bigger trucks (holdin on to them 7.3's) for heavier work & towing, so I don't need the ego machine and that makes me wonder about "turning down" an older 5.9 for economy. Does anyone know of someone doing this, and what could be expected?
Detroit finds ways to squeeze more hp out of smaller motors, how about an optional motor with more mpg's and just adequate hp? :confused2:

There is no reason to de-tune a 5.9 Cummins, the brother in law runs a 3/4 ton 4wd 1996 Dodge with some Banks upgrades and gets over 20 mpg. (yea, I thought he was a liar too, until I took a long trip with him and did the fueling).
The 1996-1997's with the Bosch P7100 was the best Dodge Cummins engine for power and economy. The later engines became lame because of emission requirements.

Get a 1996 5.9 Cummins and put it in 2wd pickup with a NV4500 tranny and a Dana 44 2.72 (or 3.07) ratio differential. 25+ mpg should be easy to achieve.
You don't want the VE pump series engine, they are limited in RPM to about 2200, lots of torque but they're miserable out on the interstate. My old 1992 Dodge Cummins wouldn't go over 85 mpg.

Me? I am so sick of the lack of performance and economy of my 2001 24V Cummins I am pleased it needs a head gasket.
I was told to put a "non-emission" cam in it when I installed the engine, like a hardhead I didn't heed the advice.
The 24V Cummins cam is ground so that it actually lets some exhaust overlap into the intake to decrease emissions, that's astonishing government regulated idiocy. Better emissions, but burn 1/3rd more fuel, only government could come up with such goofiness.
Going to install a cam when I do the head gasket.

 

[Diamondpilot]

I've been saying this for years!

Give me a new diesel making 300HP/400lb.ft. and 25+ mpg's with a 10-12k tow capacity and I'd be happy.

http://www.tractorbynet.com/forums/trailers-transportation/247490-diesel-truck-best-mpg.html

It's coming, the RAM's new V6 3.0l diesel should be around 250HP/430lb.ft. and over 23 mpg. We'll see...

Even detuned, the Cummins is still a large displacement engine. Maybe just taller gearing to keep the diesel in it's low RPM sweet spot

I still say the answer is not less HP but a automatically controlled split rear end with two or three gear sets. That with a 6 to 8 speed auto and you would have all the power needed even with a small cheap to build, maintain, and operate gas engine.


Chris

 

[Renze]

The 24V Cummins cam is ground so that it actually lets some exhaust overlap into the intake to decrease emissions, that's astonishing government regulated idiocy. Better emissions, but burn 1/3rd more fuel, only government could come up with such goofiness.
Going to install a cam when I do the head gasket.

Hmm so Cummins also used internal EGR (by means of valve overlap) ?? Never knew that. I thought only Deutz used it.

 

[Diamondpilot]

There is no reason to de-tune a 5.9 Cummins, the brother in law runs a 3/4 ton 4wd 1996 Dodge with some Banks upgrades and gets over 20 mpg. (yea, I thought he was a liar too, until I took a long trip with him and did the fueling).
The 1996-1997's with the Bosch P7100 was the best Dodge Cummins engine for power and economy. The later engines became lame because of emission requirements.

20 is nothing in a diesel truck on a highway trip. My 05 4x4 GMC 3500 got 21 bone stock and my 06 F350 has turned in 23+ many times over with a exhaust mod, 160HP chip, and intake/filter system.

Chris

 

[firemanmike69]

There is no reason to de-tune a 5.9 Cummins, the brother in law runs a 3/4 ton 4wd 1996 Dodge with some Banks upgrades and gets over 20 mpg. (yea, I thought he was a liar too, until I took a long trip with him and did the fueling).
The 1996-1997's with the Bosch P7100 was the best Dodge Cummins engine for power and economy. The later engines became lame because of emission requirements.

Get a 1996 5.9 Cummins and put it in 2wd pickup with a NV4500 tranny and a Dana 44 2.72 (or 3.07) ratio differential. 25+ mpg should be easy to achieve.
You don't want the VE pump series engine, they are limited in RPM to about 2200, lots of torque but they're miserable out on the interstate. My old 1992 Dodge Cummins wouldn't go over 85 mpg.

Me? I am so sick of the lack of performance and economy of my 2001 24V Cummins I am pleased it needs a head gasket.
I was told to put a "non-emission" cam in it when I installed the engine, like a hardhead I didn't heed the advice.
The 24V Cummins cam is ground so that it actually lets some exhaust overlap into the intake to decrease emissions, that's astonishing government regulated idiocy. Better emissions, but burn 1/3rd more fuel, only government could come up with such goofiness.
Going to install a cam when I do the head gasket.

Have you done any upgrades to the truck? If you haven't you can probably get More bang for your buck somewhere else besides a cam swap.

 

[Peacock]

The VE pump engines get the best economy due to the fact that the timing increases with rpm. They can be tuned to make impressive power and aren't nearly as limited as people think they are.

Plus they are quieter than the p-pump engines.

 

[dodge man]

I agree, an earlier Cummins will get the best mileage. I'm not sure the first couple of years won't do the best. Not because they were the most efficient, but because they were fairly light. The first few years didn't have an OD. Maybe a 89 cummins with an OD transmission with an inter cooler added would give the best MPG?

Lots of things you can do to get the best possible mileage. 2 wheel drive, regular cab, highway tires, proper gearing, synthetic lubes etc. There is a guy who gets some crazy good mileage with a common rail Cummins, but he is using extreme hyper milling techniques. I don't know the exact numbers, but somewhere in the 30 mpg's as I recall.

As far as in cylinder Egr, yes they have done that with the cam profile. On common rails, that started in Jan, 2005. 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.

I personally don't understand why someone buys a 3/4 ton diesel and expect good mileage. It's a common topic on the Cummins forums. I take some of the claims of great mileage with a grain of salt, but over 20 mpg is possible.