[Jim Allen]

Originally Posted by JacobAziza

:P
This thread has been very entertaining to catch up on!
Very.

Ok.
I genuinely have been getting 25mpg.
Thats average, over many tanks, many months.
I use the truck for moves, hauling, and transporting tools to jobs. I'll fit a 1bdrm apt in the back, boxes, furniture, everything the customer owns, all in one trip. I haul 3 tons of soil, rocks, or broken concrete. I recently moved a 2000lb safe. This is all a mix of freeway and city streets.

I don't have any instant feedback, so any number I have is an average over an entire tank.
My best mileage to date is 28.5mpg.
The 28.5mpg run way empty one way, and then about 1000lbs on the return trip.

I didn't say I haven't done any mods, just none that involved fabrication or needed a mechanic or special tools or anything expensive.
I have done quite a bit of modding (coroplast aero mods and accessory downgrades) but all things that would be in easy reach of the thread topic original poster.
I wrote up all my mods here:
Vehicle efficiency upgrades: 28.5mpg (so far) in 2.5ton commercial truck
Easy, cheap stuff.

Driving style is a big part of it too. Frank Lee is right (assuming he can run 50mph). I drive slower than normal, but that is because my truck has no overdrive- its max efficiency is around 25-35mph.
Someday when I can afford a 4spd tranny, I'll start driving 55 (the limit for commercial trucks, which- technically- mine is)


The auto companies have always known how to get better mileage. The problem isn't them. Its the American consumer. They all make efficient vehicles - to sell in Europe, Asia, and Latin America. GM makes a van - not a mini van, but a commercial van - that gets 45mpg. Sold in China. Hybrids sell here because you can get kind of decent mileage while still having A/C and thick cushy seats and 8-second 0-60 acceleration and 20 million electric gizmos and lots of truck space and room for 6 people even though 80% of our car trips have only 1 or 2 occupants.


Incidentally, I just turned my tonneau into a makeshift aerocap by putting the rails on triangle pieces of plywood.
Its too soon to say if it makes any difference at all.
If it does, I'll mention it on my original thread about the truck: http://ecomodder.com/forum/showthrea...-2-a-8613.html

And I totally agree with alohaspirit: if you are only using a vehicle occasionally, it usually makes more sense to rent one than own your own.

I got to this point on this thread and finally have to chime in. I have the same truck as you, or nearly so ('86 F250HD), and have owned it since it was almost new. I know the truck very well. It has some advantages yours may not, such as a Banks turbo kit (installed in '87) and a very precisely calibrated pump and injectors. It has some liabilities your doesn't, such as 4.10 gears, 4WD and, at times in it's life, wide tires. I have tracked the mpg since I've owned it and pretty much know what it will deliver in every circumstance. The truck has NEVER broken 20 MPG! The best it ever did was about 19 and that was with very concentrated effort at 55mph. My truck weighs 6250 pounds without driver and half a load of fuel and has the frontal area of a house. Speed is the killer with this truck and the solo rules of thumb are up to about 16-16.5 mpg at a steady 55, 14-15 at 65 and not much more than 13.5-14 at 70 (it's revving at 3000 rpm at that point... no OD).

Here's the part to pay attention to: One thing I noted right off was that the odo/speedo was inaccurate from day one. In checking around, this seems universal in that era of truck. The odo/speedo read 10 percent more than actual with the factory sized 235/85R16 tires. When I read 250 miles, I had really only travelled 225. I was seeing 17-18 mpg pretty regularly in my ignorance and feeling pretty happy about it. When I calculated the error and factored it in, that 17-18 was only 15-16. Tried to find a speedo drive gear to correct the error, couldn't, and finally ended up with taller tires (wider as well as taller, but a 33 inch tall mounted hight just about zeros the error) and it's pretty close to accurate now. The wider tires (285 vs 235) cost about .5 mpg at highway cruising speed, however.

Beyond outright bovine scatology, bottom line, our MPG claims are only as accurate as our instrumentation.

Depending on your truck's gear ratio and tires, I do not completely discount your mileage claims as fantasy, but both my eyebrows are up. If I deduct about 10 percent for odo error, and consider that you are driving at less than 50 mph, I can just about believe the solo mileage. I've never driven mine that slow for any great length of time.

Loaded??? I used to regularly tow at about 19K GCVWR with this truck and on it's best days, it could average a bit over 10 mpg... and I was happy to get it. A neighbor had the same truck with a 460 gas V8 and in the same circumstances, his best was about 7.5 mpg. I hauled about 2000 pounds (four engines) on a long trip once and the truck got about 14mpg at 60 mph.

Back to the OP, I think it's a waste to spend a bunch on money to hypermile a truck.... for the reasons so aptly expressed above. Most people don't need a truck on a daily basis. If you need on often, it's often cheaper to keep it as a second vehicle and use it when needed.