Diesel truck with best MPG

[Wnc3]

In big trucks, the big engines (within reason) get better mileage when driven at the lowest RPM before torque drops off than small engines - when driven at highway speeds. In other words, at 55 MPH the big engine will get better mileage than the small engine, all other things being equal. I loved running a bigger engine (500 HP) at 1300 RPM in the high hole doing 55 MPH. I could always get better mileage than a 300 HP doing 55 MPH. One loafs along, the other works hard when grossing 80k pounds.

I totally agree....and it helps to have a top speed programmed at 68 because after that the mpg seems to fall off fast.

 

[buickanddeere]

I totally agree....and it helps to have a top speed programmed at 68 because after that the mpg seems to fall off fast.

It's still a surprise to some that aerodynamic drag is not a linear relationship to velocity but rather to the square of the velocity.

 

[burnieman]

This thread should be shut down immediately. I've never heard a bunch of panty wearing guys go off on such tangents. You should all be taken out and given atomic wedgies for some of the comments here. Go drive your tractor or pick some tomatoes or something, anything. Go outside and play.

 

[stu jordan]

The best -CURRENTLY- available truck for mpg is a Dodge 3/4 between 1994-1998.49 (0.432 drag coefficient), NVG4500 manual tranny, 3.55 rear diff, all stock motor -PLUS- cruise control. The old dodge trucks (94-03) have the same drag coefficient as an early 80's Caprice Classic (car).

My 98.49' unloaded gets an -HONEST- 23mpg doing 62mph in 5th gear on the interstate and 21mpg around town & state hwys.

When the 2013 Dodge trucks come out they will have a better drag coefficient (0.363...better than a Lamborghini Countach). I'd suspect a 2013 Dodge 3/4 diesel with a manual tranny will surprise everyone.

Best truck/engine/tranny/diff for -MPG- in theory is a 2013 3/4 dodge, 6B Agriculture (6B-Agy) engine from Cummins, NV5600 six speed manual, and a 3.07 rear diff. Reasons:

1.) 2013 dodge drag coefficient of 0.363.
2.) Cummins Agriculture 6B burns only 199g/hr per HP @ 1,600rpm (provided Cummins isn't fudging the numbers).
3.) NV5600 would keep the engine in the sweet spot more while shifting.
4.) 3.07 rear diff will get you to 62mph at 1600rpm to maximize fuel efficiency.

With all that said I've read a person who's owned both a Deutz BF6L913C and a 6B complain that the Cummins got worse fuel mileage than their Deutz...this being hearsay. Though if you read the literature it's not obvious as to why. The BF6L913C on paper burns 205g/hr per HP @ 1600rpm...go figure.

If I were offered either motor for free...I'd have to get the Deutz cause of the coolness factor. Deutz engines are made in Germany. Germans build great ****. Nikolaus Otto, inventor of the four-stroke internal combustion engine, founded the company in 1864. Nevermind the engine is air-cooled and just plain sexy

Those claiming 24mpg in a 4x4, regardless of make/engine, are extremely lucky. I'd like to know their secret.

 

[stu jordan]

My 98' 12v dodge has never had engine work...it's got 204k miles. Only change oil every two years. Tires last 30k miles. Oil change only costs me $50.

 

[Raspy]

Those claiming 24mpg in a 4x4, regardless of make/engine, are extremely lucky. I'd like to know their secret.

It's very simple. Just like a stopped clock is right twice a day. My Cummins gets much better mileage than 24 MPG. All I have to do is take my foot off the loud pedal on a downhill and reset the computer readout. Shebang!!!! I'm gittin 40 MPG!!!!. Then run to this site and report "My truck gets 40 MPG". Who cares?

Until you use a standardized test and only report those findings it's all BS. And I can report nonsense numbers as well as anyone else. Mileage numbers only become valid over a whole tank or more and hand calced with accurate miles traveled over a representative course that isn't all down hill or with the wind. Better yet over an average use cycle of city and highway for a period of time. Say, several thousand miles. Exaggerating only fools the fool. Who cares that somebody reports their truck will get 26 MPG for 10 seconds at a steady rate of 55 MPH? Is that representative of the real world? Don't they ever go up a hill? Don't they ever drive with the engine cold or in town?

 

[Raspy]

My 98' 12v dodge has never had engine work...it's got 204k miles. Only change oil every two years. Tires last 30k miles. Oil change only costs me $50.

Hey Stu,

Don't you ever drive that poor thing? Fourteen years old and only 204,000 miles? Wait till you get it broken in, bla bla, bla. :laughing:

 

[Egon]

That Truck with the best milage is the one hooked up to the tow truck!,:dance1:

 

[Peacock]

That Truck with the best milage is the one hooked up to the tow truck!,:dance1:

Imagine the mileage a 6.0 Ford must get then.

 

[stu jordan]

Hey Stu,

Don't you ever drive that poor thing? Fourteen years old and only 204,000 miles? Wait till you get it broken in, bla bla, bla. :laughing:

I use to drive it a lot when I commuted in it and took vacations. Since going broke I ride my bicycle to work.

Now I only use the truck to haul my dog around and travel to the Ozark Mountains every other weekend. Also use it to haul corn to my place in the mountains to feed the bears...my guess is the black bears love my truck more than me. They are certainly fat and happy.

To tell you the truth the engine only recently stopped consuming oil. Before I hit the 200k mark it was using a bit of oil. Now I can't notice it consuming any.