[crazycooter]

I don't know why I can't get better than 14 mpg out of her. new vp44, air dog 100 +50 hp injectors. Before all the parts, and still after all those parts, mileage has never changed. most of my miles are highway, and average speed has something to do with it, but with an nv4500 tranny and 3.54 gears, I think I should be able to do better than 14 mpg. Any ideas? btw, 140 k on the clock

 

[kstinson]

First off I disagree with injectors increasing fuel mileage. Greater fuel mileage cannot be achieved by injecting more fuel, it is just against physics. Programmers can theoretically achieve greater numbers by the use of timing changes i.e. making the engine more efficient for the amount of fuel burned. However the information you have given leaves much to be desired. Your driving habits hold the key to mileage. If you want to enter the high fuel mileage game then you need to be conservative. Speed is the biggest killer. @55mph these trucks are still fighting aerodynamics, so can you imagine what is happening @65mph or 75mph? Keep it at 55mph and watch for improvement. Also you stated the axle gear ratio and transmission but what size and type of tire are you running. The gear ratio's mean little if the tire size is smaller or larger than stock. What rpm are you running down the highway? Aggressive tread patterns are great for in-climate weather but they are not very aerodynamic and the extra traction they offer off road equals more rolling resistance on road. Above 2000rpm unloaded your mileage will go down the gutter. Ideally these engines have the lowest base specific fuel consumption around 1600rpm (although I wouldn't tow anything heavy in this range.) Lastly what if any additives are you running. A lot of off the shelf additives contain solvents that don't play well with diesel fuel even though the manufactures claim they do. Either run nothing or add 2 cycle. Over standard diesel fuel I wouldn't expect 2-cycle to add any fuel mileage although some claim it will, if it does it is by manner of energy content not friction reduction. It is merely there to lubricate the injection pump, if you were losing a measurable degree of fuel mileage through friction then the engine would probably self-destruct in little time. Just some thoughts. Get back to us with extra info about the truck.

 

[whitewon9395]

I was getting about 17-18 mpg out of mine before any mods and I was excited about that--after all it is a 1 ton 4wd not a prius!!! after all of the stuff that I have done I'm at about 21-22 mpg empty and that's rolling about 75-80mph!!! I can obviously get it lower if I drive it more conservatively.arty018:

 

[crazycooter]

I have a buddy that I know to have gotten up to 43 mph out of his '05, and don't know anyone with a cummins of any year to get less than 19. I think that I have something inherantly wrong with my motor, or I would not get such lousy mileage. I don't have any outrageous setups or anything, she starts good, and runs like a raped ape, I don't know anymore.

 

[KATOOM]

43 mph isnt very fast at all.:rof .....but I knew what you meant.

The question you ask is one that cannot be answered by anyone who owns one of these trucks, that is unless your mileage was well below the majority, which its not. Yes, there is some who get (or claim to get) mileage in the mid 20's but for the most part the upper teens is normal. There's simply no obvious reason some Dodge Cummins trucks get great mileage and some dont. As kstinson mentioned, driving habits, tires, lift, etc. all play a part in how much effort your truck has to exert in propelling itself down the road. Fill out your signature so everyone knows exactly what your truck is and has. That way internet diagnosing is a little bit easier.

Also, I disagree with kstinson. Injectors (mild injectors) can increase mileage although driving habits tend to change with the new power increase that comes with the package, so most of the gain turns into a loss. The reason injectors can increase fuel mileage is because the cylinder energy is increased to do the same job which means that, in general, you will not need as much throttle to do the same job, so consequently the engine works less which equals more fuel mileage. At least thats the theory. But kstinson's statement poses a good argument in that more fuel shouldn't mean better fuel mileage. All I know is that most guys who install mildly larger injectors report an increase in mileage on average of a couple mpg. Also, back in the day when I increased power out of my gasoline engines through various means, it wasn't uncommon to see my fuel mileage go up as power increased, to a certain point, before the mileage dropped off as the power got really high. Well, that is as long as I was equally light on the throttle.:thumbsup:

 

[markkerkof]

43 mpg? He must also possess a very large crankshaft? His truck defies the laws of physics.

 

[crazycooter]

his 43 mpg is also with monster exhaust, 55mph, methanol injection, banks six gun programmer + intercooler+ intake...

 

[Jimbowe]

Sorry ... still don't believe 43 mpg unless it's all down a steep hill.

 

[KATOOM]

his 43 mpg is also with monster exhaust, 55mph, methanol injection, banks six gun programmer + intercooler+ intake...

About a year ago there was a magazine article, where they took a 2wd 2nd gen Dodge Cummins auto and did everything possible (and unrealistic) to drastically increase the mileage. After all the crazy things they did and how they drove it, the test never got them higher than about 30(ish) mpg. Thats it. So I cant ever believe that your buddy gets anywhere near 40 mpg, no matter what he's running. Not to mention that there's forum members who "claim" to be getting mileage in the mid 20's, and I almost doubt that too.:thumbsup:

 

[dozer12216]

It easy to get that milage if you believe the O'head console. But I can get a reliable 17 MPG pulling a 16' utility trailer with a extra 2000 pounds on truck and trailer.

 

[evegreen]

I wouldn't think anything is wrong with with your truck. I've owned two of these (98.5 auto, 2000 nv4500), both were drw with dump bodies. Of course I never drive on the highway and work them hard, but I've never done any better than 13mpgs with either one. That was ***** footing it, I usually get more like 11-12, with my foot to the floor. Driving habits and the terrain you are crossing (it's hilly where I live) influence it greatly. I also think CT puts some crap additives in there fuel that helps emissions but hurts economy.. I don't know about your state, just saying that could be a factor.

 

[KATOOM]

I also think CT puts some crap additives in there fuel that helps emissions but hurts economy.. I don't know about your state, just saying that could be a factor.

Very true. Its already been pointed out that ULSD can create up to (I think I remember right) 10% drop in mileage simply because the BTU's are less.:thumbsup:

 

[dank1945]

Re: 43 mpg truck, I believe the driver made an honest mistake when calculating the mileage. He probably forgot about one fill up in between, therefore doubling his mpg. My 2c, anyway.

 

[black2000]

I agree with dank, haha... I get 18mpg all day long doing 65mph on the highway, wether empty or with a ton of steel (literally) in the bed. I don't have a chip, I'm about to role 200k and my truck performs exactly the same as when I bought it (with 90k.) Maybe dumping gobbs of fuel to it isn't helping?

You have brakes hanging up? 100% sure everything is free and fuctional in your 4wd/ front end?

 

[Ram Fan 2]

Just replaced my VP and added a Air Dog 100. I was hoping for a mileage increase but not expecting it. Just filled up and got 14.56 on my first tank, mostly in town or county roads driving my kid to school. Basically it's the same I've been getting for years. 14 to 15 range. Sometimes I creep over 15 but not often. If I drive straight freeway at 65, I'll get about 18 to 19. It actually went up some at about 50K, when I was struggling to get over 14. The combination of AT and 4WD is just a bad combo for decent mileage. The 43 mentioned above is BS, and I highly doubt the guys that claim 25..... Just my 2 cents.

 

[manspackle]

i read in diesel power some guy was getting rediculous mileage like that. he had some crazy nitrous setup that was always active to spool his turbo at low rpm or something like that. maybe it was meth. but either way there were a couple competitors getting 30+ mpg's. and if i remember correctly the winner made 40 something mpg

 

[jasn69ste]

I filled up today and got a calculated (miles divided by gallons) 19.33 mpg, I calculate it every fill up. That number in mainly stop and go traffic for 23 miles one way to work everyday. I also just changed the tires back to the stock 265/75R/16's, I am running the LTX M/S2 Michelins. Great tire with a good tread design for mileage. I'd recommend slowly down and drive in the trucks "sweet spot" of 54-64 mph, Clifford's is about 57-59 mph. You can also watch the Instant Eco of the overhead and figure out where your best mpg's are at, that's what I originally did. Of course the Average Eco will be about 4 mpg off. If it wasn't I'd be getting 27-29 mpg.

 

[jasn69ste]

Oh and keeping the temp of your truck about 190* F will help out. Search for Mopar1973Man's write up on it, then do everyting he says.

 

[mattonln]

my sweetspot, according to my eco meter, is 1400 rpm at 49 mph lol can pull 28 mpg all day though. cruising around 60 on the coastal highway back and forth to work up and down hills i get around 19-20 depending on how fast I wanna go passing prius' either way i love this thing. oh and your op doesn't mention a timing box. GET ONE! your injectors are hurting your mpgs without timing. my truck with the comp off barely hits 16mpg.