MPG Thoughts

[TFucili]

I just pulled a landscape trailer with one motorcycle on it from Arizona to Missouri and back with my basically stock '05. I'm somewhat disappointed with the MPG. The truck runs OK, but has never gotten the sort of MPG that many claim. We ran a mix of interstate and state highways, and stuck pretty near the posted limit, so on most of I-40 we were at 74-77 MPH. We hit some thunderstorms on the way back with some cross-wind, but it was unusually calm conditions. The truck got a high of 14. 47 and a low of 13. 03, with an overall trip average of 13. 625 MPG. I was expecting 15-16 with that bitty little trailer, even with the ramp gate, which is pretty draggy. On dead flat road the truck would run about 10 PSI boost and 900 EGT(Pre-T) at 72-75 MPH.

 

[HBarlow]

The fuel economy of the 24 valve VP-44 engine is not quite as good as earlier low hp 12 valves and the HPCR is not quite as good as its 12 valve and VP-44 predecessors. The ISB6. 7 is not quite as fuel efficient as the HPCR engines were. Each generation of Cummins produces more horsepower and torque and improved driveability but gives up a bit in fuel economy.

But each generation of Cummins engines in our Dodges provides better fuel economy than V8 diesel engines in Furds and Govt. Motors trucks, regardless of what the fuel island liars claim.

I just enjoy my truck and ignore the fuel mileage. It is what it is.

That motorcycle sticking up in the windstream is a large drag because it disrupts the flow of air. And the ramp behind it is acting as a big wind brake. It's not the weight that hurt you, weight of that rig is minimal, but it sure creates a huge wind drag.

 

[Crunch]

The truck got a high of 14. 47 and a low of 13. 03, with an overall trip average of 13. 625 MPG. I was expecting 15-16 with that bitty little trailer, even with the ramp gate, which is pretty draggy. On dead flat road the truck would run about 10 PSI boost and 900 EGT(Pre-T) at 72-75 MPH.

I've noticed that weight in the bed makes little difference to my fuel economy, but the 12,000lb, two axle loaded trailer I usually pull drops it to just slightly higher than what you got. I used to run the truck at 75-80 MPH and and got around 13 MPG. Now I keep it just under 70 MPH and get closer to 15 MPG loaded, and real close to 16-16. 5 MPG unloaded. I also run cruise control whenever possible. The most important thing is to keep the RPMs under 2000. I've also run with the Michelin LT/ATX tires that originally came with the truck when I replace them. It's a very smooth riding road tire, but is sucks on the wet grass or mud. Over 160,000 miles and 9300 gallons of fuel I've averaged 17. 1 MPG. I'm also pretty religious about adding Power Service silver (90% of the time) or Howes Diesel Treat (10% of the time) when the gauge drops below the half way point. I worry more about what would happen to my injectors without it, but I'm guessing it has some effect on fuel economy. With the 4X4 I'd say your fuel economy is right on target when pulling a trailer.

 

[RMachida]

I'm no expert here but the 900 EGT and 10 psi boost at cruise suggests that maybe there is more that a little drag associated with the lift gate on the little trailer.

 

[guldam]

Guzzi Alert!!!

Oh, man that kills me. I have a 750 Ambassador and an 850T at my Mom's house. Sold my 850 Lemans, another 850T and an Eldorado with Sidecar. Still kicking myself 19 years later.

GulDam

 

[TFucili]

Guzzi Alert!!!



Oh, man that kills me. I have a 750 Ambassador and an 850T at my Mom's house. Sold my 850 Lemans, another 850T and an Eldorado with Sidecar. Still kicking myself 19 years later.



GulDam

That bike draws people wherever it goes. It actually belongs to my partner, and he is also doing a frame-up resto on a '72. I want a Guzzi next, when finances permit it. Italian bikes are my thing.

 

[p-Bar]

I'm no expert here but the 900 EGT and 10 psi boost at cruise suggests that maybe there is more that a little drag associated with the lift gate on the little trailer.

I agree gotta get the boost down that's what's killin you .

 

[TFucili]

I am certainly aware of the incremental drop in mileage as the detuning and choking off of the engines by the Eco-Nazis ramps up. I also am aware and mentioned in my post, the drag of that ramp/gate. I also pull a box trailer with a tall flat-slabbed front with much, much more frontal area than that gate, and she'll generally get about 11 MPG pulling that one. I just expected better is all, and wanted some other opinions. Thanks guys!

 

[EDKtrans]

That bike draws people wherever it goes. It actually belongs to my partner, and he is also doing a frame-up resto on a '72. I want a Guzzi next, when finances permit it. Italian bikes are my thing.

Once I saw the Guzzi on the trailer I pretty much lost the plot on the mpgs... very nice indeed. Italian bikes are my thing too but I tend to Laverdas. Still, a Le Mans is very much on my want list and any Guzzi is a lustful thing to behold.

 

[zzman]

This may not help any because I have a manual but I get the best mpg at about 63-66 mph on flat land. Hilly country seems to do better around 69-72 mpg.

The cruise helps too on flat land, hilly roads seem to be best just holding the pedal in 1 place when climbing.

 

[Crunch]

This may not help any because I have a manual but I get the best mpg at about 63-66 mph on flat land. Hilly country seems to do better around 69-72 mpg.

The cruise helps too on flat land, hilly roads seem to be best just holding the pedal in 1 place when climbing.

Same experience here. I've found that when pulling a heavy trailer hills cause too many shifts. Between Bristol, TN and Danbury, VA the hills are so... hilly that I just take it out of overdrive and live with it for a hundred miles or so. Drops the MPG, but that's a lot better than lugging the engine.

 

[EDKtrans]

Pulling a trailer in the hills, I come off cruise and when climbing keep an eye on the EGTs. As the truck starts pulling harder and EGTs climb I go to tow haul mode and let off the throttle to keep revs around 2000. EGTs should stay low but on a big enough hill I'll manually shift out of overdrive and again keep revs around 2000-2500 keeping the EGTs as low as I can. Seems to be less strain on the truck this way. My "hills" are Rocky Mountain passes and my loads run from 10,000 - 23,000lbs.

 

[RPlamondon]

I get about 10+ to 12+ in my 07+, 6. 7, auto trans, 4x4, hd, quad cab with 3. 73 gears pulling a 24 x 8. 5 enclosed trailer . I am towing/hauling about 11k across the country about 3k miles one way. If I am empty and keep it at 60 to 65 mph I can get 19 mpg. But I can't drive 55 or in this case 65 so miles per gallon drop greatly as speed increases b/c of wind resistance.

 

[JTucholke]

Lie Meter

I babied my truck on a long trip and my 2005 TDR lie meter said 27. 1. While not that good, I do believe I was well over 20 mpg when I hand calculated.



What did I do? Kept it below 60 and let the monstrous torque of my 05 accelerate me.



Now, I have a manual, and 3. 73's. AND, on that day I had no soccer moms in minivans upset at me because I was slow to get up to speed.



I have said it before, keeping my truck below 60 WILL increase MY mileage. I think if I had 3. 54's, or a gear vendors OD I could consistently get 20 on the open road.



Right now my truck says 24. 5 - but everyday of in-town driving it goes down. I am constantly being passed when I accelerate, too. Funny thing is I think some people think I'm a wasteful, big truck driving redneck - when in reality I'm probably getting better MPG than all the suburbanite crossover/SUV driving people.



O, and if I ever get annoyed by someone riding my tail I sure can surprise them if I get into the throttle... . :-laf Usually however, I try to give diesels a good name and not smoke anyone out.

 

[04blackcherry]

My brother claims around 20mpg with the horse trailer on his '05. My '04 goes down to between 12 to 15mpg with just the drift boat or two-place quad trailer behind it. Of course I am moving out in the 70-75mph range. It really comes down to speed. I spent a day with the wife drive on some 50mph country roads one day and finally hit the magic 20 mpg.

 

[jgillott]

I just got back from a trip empty to upstate NY and back with my '07 last weekend. Hand calculated 20. 99 mpg running 65 mph max. I have a hard time getting 17. 5 mpg with it when I run 70-75 mph.

 

[rscurtis]

I don't care which generation of Dodge you have, at 10# and 900 degrees you're not going to get any kind of mileage. With about $5K worth of mods and careful driving, my '03 gets almost the identical mileage my 160HP '95 did. As Harvey pointed out, the VP44 trucks do not shine in the mileage department and it goes without saying the 6. 7 does not either.

 

[Mark31]

blackcherry, you bring to mind my late uncle. He had a 65 Impala Chev with a 327. On a trip to Charleston, SC ("downhill"!), he got super mileage. Sometime later, when some of the fellows were "woofing" about their mileage, my uncle didn't say a word. Later when I asked why he was quiet, he said it really didn't matter. He just didn't want anyone to think he would "stretch the truth". Mark

 

[ENafziger]

I wish I had good news.

I've tried all synthetic Amsoil fluids in everything, 5" straight pipe exhaust, Helix 2 cam, AFE Stg II intake, AFE Bladerunner, Dynatrac manual hub conversion, Smarty PoD, TST Economy, 62/476 twins, MP-8, centramatic wheel balancers, balancemaster driveshaft balancers, Edge EZ, tire sizes from stock to 37s, Wild fuel rail, a Mitchell overdrive unit, more diesel fuel additives than I can remember, fuel line magnets, etc, etc, etc

My results?

The best fuel mileage I ever got was when the truck was 100% stock. The truck runs a lot better than stock, but with negligible effect on fuel economy.

Nothing I've added has ever improved the fuel economy noticably. At first, I thought a few things did, but after a few tanks I realized it was just because I was "wanting" it to, and was driving easier than normal.

--Eric

 

[Loren]

I've noticed that weight in the bed makes little difference to my fuel economy, but the 12,000lb, two axle loaded trailer I usually pull drops it to just slightly higher than what you got.

I'll second that. Weight in the bed doesn't affect my mileage much either, but even the smallest trailer does.



**********



TFucili,



The best thing you can do to improve your mileage is slow down. The next best thing, in my opinion, is to install a box that will advance your injection timing.



Those mileage numbers are similar to what I got with my '00 2500, Quad-Cab, 4x4.



-- Loren