Engine/Transmission (1998.5 - 2002) MPG Improvements??

[EdwardsW]

I'm new to diesels and new to towing. I used to be an Engineer for GM, now I'm hauling RV's for a living, (trying to make a living that is). I bought a 2001, 3500, 6-speed manual, 3:55 rear end. The guy I bought it from pulled race cars and said he got 15MPG loaded and 22 empty. The place I got my manditory equipment from suggested some upgrades to further improve MPG. So, I added a Superchip, 4" stainless exhaust, and a Bully Dog cool air intake. I get 11. 5 loaded and 22 empty, (at 65 MPH) pulling 30+ ft 5th wheels. It does not seem like the upgrades I selected netted me any MPG increase.



So the question is, can you really improve MPG, if so how.



Thanks,

Bill

 

[BK]

My friend with a 3500 01 HO 6spd 4. 10 rear, just a box, was getting about 15mpg the year before last, when we went up state to near Buffalo from, LI. A 400mile trip. He tows a 32' 5th wheel.



I got about 12mpg in the mountains with a 2500 99 Auto 3. 55 rear, all stock, towing a 30' TT. I was also loaded with 40 gallons water in the bed, along with a lot of firewood.

With that, we were probably close in weight, but he was still probably heavier.

I don't remember which box he has. Looks like a Puck.



I just did the same trip but this time without a trailer and with 33x12 radial E rated aggressive AT tires and a 4" exhaust. I got 18. 5mpg.



You'll probably see an improvement if you back it down to 60 or 55.

Are your running any gauges?

EGT/Boost?

 

[EdwardsW]

no gauges, don't know what I need to be watching yet. A fellow at ATS suggested I move from the superchip to the Edge Juice with Monitoring. He thought that might help my MPG. I would certainly give me more to tinker with and then I would have some monitoring.

 

[Hohn]

I'm new to diesels and new to towing. I used to be an Engineer for GM, now I'm hauling RV's for a living, (trying to make a living that is). I bought a 2001, 3500, 6-speed manual, 3:55 rear end. The guy I bought it from pulled race cars and said he got 15MPG loaded and 22 empty. The place I got my manditory equipment from suggested some upgrades to further improve MPG. So, I added a Superchip, 4" stainless exhaust, and a Bully Dog cool air intake. I get 11. 5 loaded and 22 empty, (at 65 MPH) pulling 30+ ft 5th wheels. It does not seem like the upgrades I selected netted me any MPG increase.

So the question is, can you really improve MPG, if so how.

Thanks,
Bill

I hope you aren't the guy who decided to put the starter solenoid so close to the exhaust, lol!!!

There's not a whole lot you can do to add MPG. Check tire pressure. Open up air in and out.

22 empty is very good.

Towing MPG is mostly about speed and gear management. You might be able to get up to 13, but not much more... 5vers are murder on MPG.

 

[EdwardsW]

On the tire pressure, should I max it out? Also, I am running 62. 5 mph at 1800 rpm. I was told that the sweet spot would be at 1600 rpm. Should I consider going to taller tires. So that I can run a little faster and lower my rpm at the same time?

 

[BK]

Your tire pressure should probably be maxed out only when your towing.

I thought the sweet spot was a little higher than 1600, I thought ~1800 - 2k.

But not sure.



A mechanic / driver friend of mine, trained by Cummins when he was hauling, told me they preached, 5 and 6 as the magic numbers to be nice and to get the fuel milage.

No more than 5psi for boost, and no more than 600degF for EGTs while cruising.

Select the right gear, get those numbers and stick with it based at the speed limit you have. The lower the better. Great for the life of the motor, and great sweet spot for the Engine.

 

[Hohn]

Most efficient rpm in terms of BSFC in 2000rpm.

That's doesn't mean you'll get the best mpg at that speed, though.

Best mpg is the highest gear you can efficiently pull, turning at the lowest RPM the engine efficiently will operate at.

Usually, about 1700rpm in OD is the best compromise between efficiency at aero drag. 2000 rpm is more efficient, yes-- but there's a lot more drag at 70mph than 60, and that wipes out any efficiency gain.

 

[blacksheepdiesel]

I would suggest the Smarty for better fuel mileage.



Your friend may have been telling you what the overhead console mpg read, not accurate at all. Only way to know is figure by hand which is what it sounds like you are doing.



Also, you might want to check the IAT (intake air temperature) sensor as it will adversly effect mileage if dirty.



Trent

 

[EdwardsW]

I checked out the MAD Electronics website(Smarty) they do not recommend using the fuel saver setting when towing. And that is what I am looking for, better economy when towing.

 

[Cummins Thunder]

I HIGHLY doubt you will see any MPG gains by switching boxes/programmers .



You would be taking a step backwards, by putting on taller tires.

About 1900 - 2300 rpm should get you best mileage while towing.



CJ

 

[RAJohnson]

Engine RPM, EGT and Boost. Are all parallel to MPG weather towing or not. I get around 13. 5 MPG towing and 20-21 MPG not towing. Like stated above check the IAT and then get some gauges, before adding any other Mods. After the gauges you might want to look at the Gearvendor Overdrive as a all around good investment, help's keep the MPG when towing or cruising. I run mine by the EGT and Boost gauges as far as when to shift.

 

[Mundgyver]

Towing a 5th wheel is like towing a giant air-brake. These trucks are designed to tow at about 65 mph efficently. I would suggest you install a set of gauges, boost, EGT, Fuel pressure.



If you are going to switch up to a box I would suggest the Edge-Comp. From personal experience, I own both an Edge-Comp and the Smarty. The Edge will yield right at . 70 mpg better than the Smarty. I have done the trips and the testing with both.



The biggest mpg gain I got was when I installed a set of Bosh 275's and then the Edge. I got 1. 4 mpg from the 275's and 1. 3 from the Edge for an overall gain of 2. 7. Cruising empty I get anywhere from 22. 9 to 23. 8 with the Edge in 1x1. With the Smarty and the Edge turned off, I got 22. 2 mpg. Understand that I am not bad mouthing here. This is just what I have seen.



Loaded up to 23,000 lbs CGVW, Gooseneck Flatbed with empty 5 ft welding bottles and the Edge in 1x1 over 400 miles from Sherwood, Oregon to 30 miles East of Bend, Oregon and back, through Santiam Pass, I averaged 15. 4 mpg.



My signature show my mods. Guages can tell you allot. The EGT is the quickest indicator of fuel usage. If you know what your peak torque rpm is, that will help out for selecting your gears in the uphill runs.



Driving style will play a big part also. I think you can get another 1 mpg on the bottom end loaded up. Your top end unloaded should be able to come up about 1. 5 mpg. Speed is you enemy above 65mph for mileage.



Oh- almost forgot. Tire pressure as already mentioned for the truck should be max, but also make sure the trailer tires are max also.

 

[w gilmer]

Mundgyver. Which Porogram # On The Smarty Were You Using When You Grossed 23,000 And Got 15. 4 Mpg? Best I Ever Got On Edge Ez Pulling That Much Weight Was 12. 5 . That Was From Trapper Creek Ak To Roseburg Oregon. I Have Removed Edge And Now Have Smarty. I Will Be Moving Next Month From Ak. To Oregon Again With Similer Weight. I Have Auto 99 And I Tow Only In Drive, About 25 2600 Rpm. I Hope The Smarty Will Help. Any Advice Will Be Appricated. Thanks Walt.

 

[Mundgyver]

At the time I was at 23,000 lbs, I did not have the Smarty. All I had was the my Edge-Comp at the time and I was using it in the 1x1 setting.



When I picked up the Smarty from Bob Wagner up in Washington last month, I had made the run up to his place using the Edge in 1x1 mode and got 22. 95 mpg. This was empty of course. We loaded up the Smarty fuel saver program #1 at that time and I made the return trip to my place in Oregon with the Edge-Comp turned off driving at the same speeds I did on the way up.



I lost . 7 mpg on the return run getting 22. 23 mpg. The Smarty is wonderfull for what it does and when used in conjunction with the Edge-Comp it will bring a big . I did 187 miles up and topped and hand calculated and 179 back and topped and hand calculated to get these numbers.



Don't throw your Edge out yet To date I don't know any one that has tried this experiment I just described above. I have another trip over to Idaho comming up wich is 715 miles one way. So I intend on repeating the experiment using the Smarty on the way over and the Edge on the way back. Should prove interesing. Normally I will get between 22. 9 to 23. 8 on the Idaho run, depending on weather and head winds in the Columbia Gorge.



You indicated that you are driving an Automatic, that makes a difference also as I have a 6 speed. Make sure all your tires are at their max recommended pressures on both the truck and the trailer.

 

[Demons_Ram]

All,
Plenty of good mile per gallon (MPG) info from Cummins/ Dr. Diesel (dead link updated 24 Dec 2009)

http://www.everytime.cummins.com/assets/pdf/MPG_Secrets_Whitepaper.pdf

 

[Mundgyver]

Nice booklet

 

[SHobbs]

no gauges, don't know what I need to be watching yet.



Am I the only one that missed this statement. You need a fuel pressure guage, pyro, and boost to name a few.

 

[BK]

no gauges, don't know what I need to be watching yet.



Am I the only one that missed this statement. You need a fuel pressure guage, pyro, and boost to name a few.

No, I orginally mentioned he should have gauges and why. . that was his response to my originally asking if he did and saying he should.

 

[SHobbs]

I stand corrected, lol.

 

[BK]

I stand corrected, lol.

no problem.

You asked, and it was a good point.

Great Mind think alike.



They really do help to drive for fuel efficiency.