Fuel economy with a diesel truck ?

[MrJimi]

MrJimi,

Yeah, I'm not too worried. I have a part time landscaping business so I only anticipate 2-3K miles per year. What I would like to know is what kind of weight I can haul with it. It's a bit strange, GVWR is 15016. GAWR is 5K front, 11k rear. That equals 16K according to my math.

Here's a pic of the orange beast...I suppose that it matches the tractor ...but, at least it will be hard loose in a parking lot

From all I have learned about GVWR here, I would say take your GVWR on your door and deduct the weight of your truck ( full fuel etc. )and you should be legal and make sure you keep the grand total under 26,000 pounds and you should be fine
All this is from a newbie with great teachers here on TBN
Happy Haulling
Jim

 

[Builder]

MrJimi,

Yeah, I'm not too worried. I have a part time landscaping business so I only anticipate 2-3K miles per year. What I would like to know is what kind of weight I can haul with it. It's a bit strange, GVWR is 15016. GAWR is 5K front, 11k rear. That equals 16K according to my math.

Here's a pic of the orange beast...I suppose that it matches the tractor ...but, at least it will be hard loose in a parking lot

The axle ratings added together do not necessarily equal the GVWR. There could be a dozen other factors that "limit" GVWR. Sometimes it's tires, wheels, brakes, emergency brake rating, spring packs, etc.

Axle ratings are one of several factors that decide the GVWR or GCWR of a truck.

 

[Builder]

All right, you guys are scaring me. I picked up a 2000 GMC 3500HD Dump with 6.5TD with 5.13 rears on thursday. I didn't know it had 5.13's. It's a 15K GVWR. What do you all think I can get ...8 mpg?

Depends on the type of driving you do. My guess is that with a 6.5TD @ 210HP and if it's all highway you'll be in the mid teens. If it's all stop/go and fully loaded, could be 10 +/-.

 

[drtydeed]

Depends on the type of driving you do. My guess is that with a 6.5TD @ 210HP and if it's all highway you'll be in the mid teens. If it's all stop/go and fully loaded, could be 10 +/-.

Thanks for the info. When I drove it home, it was taching about 2400 at 60 mph. Fortunately, most of the driving I'll be doing with it are secondary roads at 45 mph. For the $ paid, I wasn't concerned too much about mpgs.

 

[capt_met]

'03 3500 dmax/allison w/ 3.73 gets 18 avg. interstate 16 in town, towing 14,000# it drops down near 10 maybe 12 on the highway. don't see much hwy when it is loaded though. trucks a a superchips programmer at +35HP (towsafe). 4" staright pipe and cold air intake.

'94 F350 17 hwy light, 17 in town light, when towing 14000# dropped to 7-8 hwy or city. does better with lighter weight. not sure which rear end it has but it is 5 speed manual. no aftermarket parts.

 

[Builder]

Thanks for the info. When I drove it home, it was taching about 2400 at 60 mph. Fortunately, most of the driving I'll be doing with it are secondary roads at 45 mph. For the $ paid, I wasn't concerned too much about mpgs.

That's a good application for your truck. 4.88's, 5.13's, 5.38's are all gas guzzlers on the highway and generally cause your truck to run at an RPM level higher than the sweet spot. My truck has an O/D transmission to get my RPM's lower on the highway, so even with 5.38's I can comfortably cruise up to 70.

As long as you're moslty on back roads ~45 MPH, you'll be in good shape.

Nice truck you have there. Looks like an old Penn DOT or state highway truck.

 

[MrJimi]

Builder, what is that "sweet spot" on a tach ? I also have OD but I don't think it does much. I have the 4R100 transmission
Jim

 

[Builder]

Builder, what is that "sweet spot" on a tach ? I also have OD but I don't think it does much. I have the 4R100 transmission
Jim

You O/D does a LOT to help save fuel, if you don't believe me, try running a long highway trip with O/D turned off! You'll consume a lot more fuel!

For fuel economy, I always thought of it as the spot on the tach where you consume the least fuel. Every truck is different. You have to own/operate the truck for a while to see where it is.

For power, I would consider it as the point where you make the most power.
Every diesel engine has a "peak torque" rating. Find the power curve of your diesel and look for the highest torque rating on the curve and what RPM it corresponds with. That will be your sweet spot for power.

 

[MrJimi]

If you want a good laugh, I have not driven my truck on road yet, my wife did and she says 2,000 RPM at 55 MPH ?
I will get it all together before I start driving it
and I have 2002 7.3 turbo with the 4.88 rear/limited slip
Jim

 

[Builder]

If you want a good laugh, I have not driven my truck on road yet, my wife did and she says 2,000 RPM at 55 MPH ?
I will get it all together before I start driving it
and I have 2002 7.3 turbo with the 4.88 rear/limited slip
Jim

All the more reason to worship having O/D in your tranny.

4.88's are not highway-friendly gears.