1991 F-250 2WD 4.9L I6 MPG estimates

[IsaacCarlson]

OK, i want to see what everyone thinks i can get out of my truck. My plans a are:
complete check-up
vacuum guage
full grille plug
air dam
slant-back
WIPER COVER housing thing
smooth wheel covers
rear wheel skirts
full pressure in the tires
maybe a belly pan
synthetic oil for everything
maybe longer gears
those little thing-a-ma-jigs that split the air in front of your tires
better air filter
new o2 sensor
new plugs
new wires
complete tune-up
OH, and the odometer says it only has 28,084 miles on it!!! AND I GOT IT FOR 100 bucks!! (from a good friend)

THINK I CAN HIT 30MPG??????????

[Frank Lee]

21. Maybe 23.

[99metro]

I have to agree with Frank. Not too many people are getting much over 20 mpg. Hypermiling, you "might" hit very low 20s with the wind to your back.

Make the truck light, low to the ground, high pressure and skinny highway-tread tires. Gap the plugs to .055 with a quality high voltage coil and high quality wires, plus advance the timing a little. I wouldn't put a whole lot of $$$ into it because the return on your investment would be in years. But if you are doing this for proof-of-concept rather than saving money, then this will be an interesting journey!

[McTimson]

How many digits does the odometer have? Can it fit a hundred thousands digit?

Regardless of the aerodynamic mods you do, you're still powering it with a 4.9L V6. It's going to burn a lot more gas than most cars, even if it is aero-modded.

[Big Dave]

I'm with Frank. 23 MPG if you hypermile your brains out.

The old 300 I-6 is very durable but is a known gas-hog.

Automatic or stick?

[IsaacCarlson]

.

[basjoos]

Install an mpguino and then see what your instantaneous mileage rises to when you draft someone. The mileage you get while drafting is the potential mileage increase that aero mods could give your vehicle. This is a quick and easy way to see if the aero mods are worth doing.

[Frank Lee]

That's a good idea!

[Big Dave]

Manuals are actually much better for FE than automatics.

30 MPG is a tall order. I know. That is my goal as well. The aero mods you propose are good as far as they go, but it profits you little to cut your aero drag down when your engine & drive train are stabbing you in the back.

To get to 30 MPG, you have to move beyond a DIY project and get serious. In addition to your proposed aero mods, here's what I would recommend if you want 30 MPG bad enough:

Lower the truck. There are 3-5" "slam kits available.

Ditch the 300 and swap in a 4BT3.9 Cummins. Great torque & very efficient.

Ditch the truck transmission and get a T-56. They are found in Mustangs.

Search ringandpinion.com to find the numerically lowest ratio you can get.

Get low rolling resistance tires. Search this site. We discuss then endlessly.

We are talking a $10-15,000 project depending on how much work you can do youself. Seems like a lot, but how many $15,000 truck can you buy that get 30 MPG.

Like other parameters of performance, it is all a matter of money. How much MPG do you really want?

Obviously you start with recalibrating the nut behind the wheel (you). It is a proven fact that better driving is absolutely essential. While yoiu are retraining your driving habits use our garage fuel log function to establish a baseline.

[roflwaffle]

Originally Posted by Big Dave

We are talking a $10-15,000 project depending on how much work you can do youself. Seems like a lot, but how many $15,000 truck can you buy that get 30 MPG.

There are quite a few pickups out there that can pull ~30mpg after adjusting the nut behind the wheel, and even a few one ton pickups that can see that w/ the right modifications, all for way less than fifteen grand.