Join Date: Aug 2004
Location: The Motor City, Michigan
Feedback Score: 0 reviews
It's completely possible.
First, notice that he's claiming 28 average mi/gal. Second, notice that there's no mention of his driving style, location or the weather. (Warmer air = lower air density = less aerodynamic drag. So does higher altitude)
In 1986, it was possible to buy an F-150 that tested out at 20/25 mi/gal. That was with a 5.9-liter gas engine and a 4-speed, neither of which were really designed or calibrated for fuel economy. (if fuel economy was your priority, they offered the Ranger and the Courier)
An F-250 is about the same size and has about the same drag as an F-150. With higher-pressure, lower-rolling-resistance tires, conservative driving and the low final-drive reduction ratio, it's not terribly surprising.
Have you ever noticed that an 18-wheel Class 8 tractor-trailer is ten times the weight and has five times the frontal area of an F-250, but consumes only 2.5 times as much fuel?
Start with a final drive ratio that results in the engine turning 1500 rev/min or less at the posted speed limit. Ditch the overdrive; that adds a pair or two of gear teeth in mesh and will cost you 4%. Ditch the notion of 300+ Hp and install something much more reasonable. (ever notice that 80,000 pound semis have about the same horsepower as a Superduty?) To restore the pulling power lost, add two more gear ratios below what's now called "first". Give it a reasonable amount of ground clearance and clean up the aerodynamics. Finally, keep it down to the posted speed limit. (Better yet, run the Federal Test Procedures for consistency)
30 mi/gal doesn't even sound difficult, if there's a desire to do it. Unfortunately, horsepower, not fuel economy, sells pickup trucks.
Douglas Campbell, P.E.
1986 Isuzu P'up, 177,673.8 miles.
- Hella headlights (highly recommended)
- DOT C-2 back end (also recommended)
- R-12 air conditioner converted to R-406a. Saved ozone and money
- 4.1:1 final drive converted to 3.4:1. Quieter, better mileage but it's a good thing I live in the flat Midwest.
- 9/22/2007, age 21: Still running well when reluctantly sent away for reincarnation, due to body & frame rust.
- Never did get around to converting it to french-fry oil, which is why I originally stumbled upon this site.