Engine/Transmission (1998.5 - 2002) Quest for fuel economy

[Bratton]

There seem to be a lot of members working on high horsepower and torque, but one of the other reasons a lot of us bought our trucks is to get good fuel economy.

Is anyone out there using "bombs" or other modifications to try and maximize fuel economy? It sure would be interesting to see how high the mileage could get. There is a lot of variation in the mileage of these trucks, a lot of people are claiming 20+Mpg and others like me seem to get closer to 14. That would suggest to me that there are things that can be done to get much better mileage. BD

 

[Houser]

Hey Bratton

Looks like your truck is basically the same as mine. And I get over 21 on a long HWY run empty. Winter commuter driving is in the 18/19 range. Summer is a little better. I picked up 1. 5 mpgs when I installed the EZ. I drive a lot of HWY miles (40) to work so the truck gets plenty warmed up. It takes the first 10 miles to get fully warmed up and for the mileage to get maxed out. If you have relatively short commute to and from work you are probably not really seeing your max mileage potential. Also I usually drive the speed limit and use cruse all the time. If I got a mileage increase from the K&N filter it was't noticeable. Towing my 24' travel trailer on the HWY @ 60mph ish I get 13/14 mpg on warm day. winter Driving (below 0 f )can be as low as 10mpg with the trailer in tow.





Houser

 

[RACE427]

more mpg

I am with you both, rather get more miles per gallon on my over the road trips than really look for increased power. If I could get both then that would be great !

 

[Turbo Tim 1]

Speed is the first thing that kills mileage, if I do 73 most of the time I get around 15-16 mpg, if I slow down to 65 I have gotten as high as 19 but I have 4. 10's and a dually. I wonder about the accuracy of the pump timing setup on the 24 valves because I've heard numerous times about guys changing their VP and then they loose 2 or 3 mpg so if you've got a fuel sucker from the factory that could be part of it. One of the biggest things I did in the beginning to get mileage up was change the Intake Air Temperature Sensor (IAT). I picked up 2 - 3 mpg. I didn't gain anything with the Edge Comp but that's because I like to feel the power. I've always heard the VA is the best box for gaining mileage and also 275 injectors help. There is talk about a 180 degree thermostat helping but it didn't help me. I'd be ticked if I had your set-up and was getting 14 mpg, it definantely should be getting better. Somewhere in the archives there was a guy who wanted to see how good of mileage he could get with his 2x4 2500 so he drove like grandma for a whole tank and ended up getting 27 mpg, usually he got in the low 20's I think. Pretty impressive for a 6,000 lb truck.

 

[hcpBILL]

Mine got 21-22 @ 65 mph before I started to modify it. It now gets the same mileage but I added 4" exhaust with 2 mufflers (I like it really quiet) and the 275 HP injectors and nothng else. There is a nice improvement in power and so far the mileage has not been hurt a bit. Towing it gets better mileage than before by at least 1/2 MPG.

Bill

 

[Bratton]

HCPBill:



Did adding that 2nd muffler have a significant effect on dampening the noise? I don't want to change this to a noise reduction thread but I haven't heard of that approach before.



Your mileage is really good, part of my problem may be that here in Montana we usually drive around 82 mph on the interstate.



BD

 

[RowJ]

Just picked up 1.5 mpg

Returned from 3,000 trip (Dallas to L. A. ) just yesterday. After crunching my numbers, am reminded of a thread I read a year ago and had forgotten. It refered to having to pull a heavy load to get the CTD loosened up - or something to that effect.



I don't tow but do short trips (up to 2 hrs) at gross wt often. My mileage has never been better than 16. 5 - 17. 5 mpg. Drove to L. A. at 9200 lb, 75 mph, 1,500 miles in day and a half, headwinds all the way. Got 16. 2 mpg; was happy considering 4x4, automatic. Return trip - empty, headwinds also, 75 mph, got 18. 6 mpg. Best ever!



Many say mileage increases after 25,000 - 30,000 miles. I'm now at 37,000, so this may be it. Suspect working engine hard for a while is more important.



Have never seen plus or minus from ANY mods! Am sure driving slower would be biggest increase in mileage - just seem to want to get where I'm going too much to be able to test this theory.

 

[hcpBILL]

Bratton-



When I go 75+ it drops to 19 (empty). The good news was the towing mileage. I did a trip through the mountains loaded pulling a 13,000# GN trailer. 1600 miles, Boulder Colorado to Las Vegas to Albuquerque and then back to Boulder and got 11. 1 MPG average over the whole trip. That is about . 6 MPG better than what it got with the stock injectors. Plus it did a much better job of pulling the hills with the 275 injectors. I had to watch the exhaust temp in 4th gear climbing steep hills, it wants to go to 1300 degrees. That's too hot for me. 5th & 6th gear you don't even have to look at the gage.

I think mine is a bit unique, one of the few 6 speeds with the ETC motor, 235 HP. That may be why it gets good mileage.

I did not like the sound with one muffler. It had a loud drone above 2100 RPM. I called Jardine and they sent me a little muffler to put in upstream of the one in the kit. I think it was 14" long. That did the trick, both mufflers are straight through Magnaflows and it's nice an quiet. It also does not sound like anyone else's truck, a unique sound with the two mufflers.

Bill

 

[Intelman34]

Fuel Additives

Synthetic Lubricants



I am putting my 275s in soon in hope for a bit more mileage too.

 

[Texas Diesel]

Some members have reported a slight (0. 5-1. 0) MPG increase by switching to a Cummins specd 180F thermostat instead of the Dodge specd 190F.

 

[ceastmen]

Fuel Milage

Hi Everyone,

Fuel milage was one of the reasons I bought a Dodge/Cummins.

My friends with Powersmokes can't even come close.

My last trip to the Western Slope of Colorado from Evergreen

Colorado I got 17. 8 mpg (535 mi. 29. 95 gal. )

On the way over I was towing my friends Army Trailer (not the

lightest built, I wish he'd sell it to me). I left the trailer at our

property. I had railroad ties,Quartz rock, wagon wheels, picnic table, tools etc.

I drove the speed limit 95% of the time 75 mph. where posted.

That is climbing 2 passes, Eisenhower Tunnel, Vail pass and then

over Grand Mesa (10,000+ ft. elev. )

I know that the VA gets better milage than the Edge box I have

both, my 2 cents.

To say I like what my Truck does is an understatement, I love it!

Chuck

 

[Big A]

I'll have to say that the 275hp injectors made a nice difference in mileage. But I also have to agree with the fact that if you work it hard, it will yield better mileage with time.

Big A

 

[BKilbury]

my mileage has stayed very close to same pre and after light bombs. unloaded highway at 72 mph i get 20. 5mpg.

it will now however much more easily pull our modest travel traler, it weighs 6000 lbs.

 

[PRout]

Re: Fuel Milage

Originally posted by ceastmen



My last trip to the Western Slope of Colorado from Evergreen

Colorado I got 17. 8 mpg (535 mi. 29. 95 gal. )

Thats about what mine gets (calculated & calibrated odom) w/ the VA & DD3's, 180 thermostat, 4x4, mud tires. Also do alot of city driving, so I feel fortunate it is that good. Have never seen more than 20, even on long trips.



The 180 degree thermostat did not seem to help on mine, either did the FASS (although the mfg claims an increase). The VA may have helped a little, but sure peps it up.



People might want to indicate 4x2 or 4x4 on these threads, because of inherent loss w/ a 4x4, and numbers can be a little misleading when trying to determine what helps & what doesnt.

 

[slo-ryde]

Here's a link to a Cummins PDF, it was intended for big rigs but a lot of the info applies to us too...



http://www.cummins.com/na/pdf/en/products/truck/Fuel_Econ_for_web.pdf



It's nice to see others interested in fuel economy. My truck is getting 20 to 22 mpg unloaded. The sweet spot for my motor seems to be just under 2,000 rpm which puts speed at 68 to 69 mph.



Some bombs I'm considering (with fuel economy in mind) are:



1. Turbo Air Guide (TAG). Still waiting for some dyno testing by independent shops to confirm performance/economy gains.



2. 275HP Injectors (after engine warranty expires). Seems everyone with these injectors are getting better mileage and the extra hp is kind of cool too.



3. Electric cooling fan. Pricey but reclaimed hp gains should yield improvements in mpg.

 

[SGreenwood]

Everyone should list the following details to truly compare apples to apples

1) auto or manual trans

2) gear ratio "its a major factor"

3) tire size "it affects the gear ratio" and the speedo must be corrected or adjusted if using other than stock tires

4) 4wd or 2wd

5) load empty or full

6) hwy or city driving

7) always hand calc. milage at fill-ups don't use the overhead computer it is only a guide



for guys with 410 gears consider taller tires but watch the width it could hurt instead of help the MPG just a suggestion consider the cooper discoverer LT ( LT 255 / 85 R 16 ) it's 33. 02" tall and about 10. 0" wide with nice all purpose tread pattern for the 4x4's and will still fit on the factory 6. 5" rims It should bring your ratio up to 377 it is a lot ceaper than converting to 19. 5 rims :

 

[cpeters]

I hand calculate every tank and drive mostly drive hwy to and from work, I now have my milage down to a science. 99 2wd 5spd 3. 54 1900-2000 rpm = 65 mph 19. 5-20. 0 I also have 265 tires and I don't try to figure the difference from 245's if I take a long trip to the ranch at 75-85 mph it goes down to 17. 0, met a guy at the pump the other day who said he gains 1-2mpg's by adding Marvel Mystery Oil to every third tank so I tried that and bumped my to and from wk to 20. 5-21. 0 you guys might want to try it.

 

[Bobalos]

I have a 99, 2x4, Auto, Quad cab, bone stock & track mine @ every fill up. I am getting 16. 5 to 17 for the last 10 or so tanks. this is all city trafic (I live in San Diego, CA). I took a trip up the road on a sunday morning & got about 3/4 of a MPH better.



I would like to increase it as well, however am not willing to dump a ton of $$$ into it to get a slight return on my investment. I dont tow a lot so there is not a LOT of motivation for me to make lots of changes to my truck. Its just got to get me to the drag strip every couple of weeks or so.



I must say though this is my first Desiel & I LOVE it. great truck, Lift pump issues aside.



Bob

 

[RichardMartin]

better milage

When I bought my truck i was told to expect good mileage and yet i am still looking for better than10 to 12 mpg. last effort i am looking for an extra overdrive. a bit costly but should even out in the end and eventually come out ahead. i think?

 

[KIseminger]

Originally posted by Turbo Tim 1

One of the biggest things I did in the beginning to get mileage up was change the Intake Air Temperature Sensor (IAT). I picked up 2 - 3 mpg. I

Tim-



Need more info... ... What did you change the IAT to? Did you change the stock sensor or is there a different sensor to put in?



-Kyle