MPG,semi-pickup's

[poppie]

was talking with a camper of mine the other day and he was wondering why a newer OTR tractor's pulling 70,000#-80,000#'s can get 5 1/2 - 6 MPG and his 2008 F450 6.4 pulling 16,000#'s get's 7.5 MPG ,or my 2002 F350 7.3 PSD pulling 13,480 #'s at the scale,20,900#'s total getting 9.5-10 MPG,how do the big boy's move that much weight on that amt of fuel????,any idea's?????.

[ghunt]

10 speed transmissions and 2 speed rearends maybe? Good question...

Hell, don't some of the new tractors get 8-9 mpg?

[texastech_diesel]

Well once you get 80,000#s moving, that big engine can probably keep it going without really trying. Buddy of mine drives a Freighliner with a 14L engine... its only 2.33 times my displacement. Throw in 9 forward gears and you can pick a good powerband to stay in.

[rob_nc]

OTR engines have more torque. The same 425 hp also has 1500lb.ft. of torque. Also, the power curves are better optimized and the engine almost never revs over 1800 rpm. All of this with a low rpm cruise speed equals MPG.

[poppie]

the avg OTR tractor with empty trailor weigh's about what the avg P/U & 5'th wheel weigh's,add on 50,000#'s of fright to the OTR rig and something does not square,take's X amt of BTW'S to move X amt of weight,anyone from MIT on here,help us out!!!.

[origcharger]

I imagine OTR trucks are optimized for the job they do, as opposed to your typical pickup truck thats setup as a compromise to try and do everything.
Hows the mileage on OTR trucks that meet the 2007 emission standards faired?

[FARM69]

Well, in the rig I drive usually gets about 3-4 depending on how hard you push her. The newer mercedes diesels are supposedly the best on fuel milage.

You might be able to find a little daycab with a light, light aluminum trailer to wiegh 20,000 empty (or a flatbed).

Orig, I think you hit it on the nail. OTR have the gearing and the powerband right where you need it. Out of our two trucks, both Pete's, one is definitely the highway king and the other is the backroad overweight pulling machine.

I can't help ya with the emission question. I don't know of anyone that has purchased a brand new truck.

[ghunt]

Speaking of square, that's another thing...a truck with a box trailer is like a brick moving at 70 mph. Has to be a lot of drag on that thing.

[tjc transport]

my mack running loaded at 80,000 all the time will only get 2 1/2 to 3 mpg.

but if i go out and drive around for 10 hours empty(23,480lbs) with the cruise set at 65mph, it will get almost 11 mpg.

[dascro]

Originally Posted by tjc transport

my mack running loaded at 80,000 all the time will only get 2 1/2 to 3 mpg.

but if i go out and drive around for 10 hours empty(23,480lbs) with the cruise set at 65mph, it will get almost 11 mpg.

Do you have the MP8? I thought they got better MPG than that when loaded....

[tjc transport]

2004 RD686 with a 400hp renault/mack pos diesel, an eaton fuller 8LL trans, 44k rear suspension, 12.00X24.5 rubber on the rear, with floaters on front and the air tag. . not sure on the gear ratio off the top of my head, but top speed is 74mph.

i carry 120 gallons of fuel, and the worst i ever got was the day i ran loaded for 480 miles, and used 198 gallons. the bast i ever got was coming home from Port Jarvis N.Y.
i filled up at the end of the shift, and went into the hotel for some shut eye. after i got some sleep, i drove home. 100 miles, and only took 9 gallons.

[rob_nc]

Originally Posted by tjc transport

2004 RD686 with a 400hp renault/mack pos diesel, an eaton fuller 8LL trans, 44k rear suspension, 12.00X24.5 rubber on the rear, with floaters on front and the air tag. . not sure on the gear ratio off the top of my head, but top speed is 74mph.

i carry 120 gallons of fuel, and the worst i ever got was the day i ran loaded for 480 miles, and used 198 gallons. the bast i ever got was coming home from Port Jarvis N.Y.
i filled up at the end of the shift, and went into the hotel for some shut eye. after i got some sleep, i drove home. 100 miles, and only took 9 gallons.

Sounds like you've got 4.64 rears. What do you haul that requires this heavy of a truck?

[poppie]

Originally Posted by tjc transport

my mack running loaded at 80,000 all the time will only get 2 1/2 to 3 mpg.

but if i go out and drive around for 10 hours empty(23,480lbs) with the cruise set at 65mph, it will get almost 11 mpg.

................. 2 1/2-3 mpg, Is that all city/urban driving?,when I was hauling stone for sewer job's in a day cab Mack @ 70,-75,000 #'s the ole girl got 5-5 1/2 running I- 90 from the pit at beverly & I-90@ Elgin Il to the Schumberg I-90 & 53 area,aprox 40 mile's or so and that was with ,at that time,a 28 year old hunk-o- junk with a 237 and a 5 speed,the ole girl was flat wore out!!!!!!!.

[SANDDEMON08]

Originally Posted by poppie

was talking with a camper of mine the other day and he was wondering why a newer OTR tractor's pulling 70,000#-80,000#'s can get 5 1/2 - 6 MPG and his 2008 F450 6.4 pulling 16,000#'s get's 7.5 MPG ,or my 2002 F350 7.3 PSD pulling 13,480 #'s at the scale,20,900#'s total getting 9.5-10 MPG,how do the big boy's move that much weight on that amt of fuel????,any idea's?????.

Your F-450 SD proably runs 2400 to 2700 rpm running down the road 70-75, the over the road trucks are only running 1600 to 1800 depending on gearing. You tach out at 3400 +or - with your 6.4 they tach out at 2100-2200 + or - . Just my .02

[mudmaker]

The new emission standards have killed the mileage on OTR trucks as well.