Better mileage than average new passenger vehicle in 2.5ton commercial truck!

[NHRABill]

Figuring your gear ratio is easy.

Jack the complete rear axle off the ground

Mark a tire with a line

Mark the drive shaft with a line

have one person turn the tire a complete revolution

while the other person counts how many times the drive shaft turns.
for example if you follow the above instructions and your 1 tire revolution may = 4.10 turns on the drive shaft and there is your answer.

a 3.73 rear gear is a nice truck gear for people that haul with a 3 speed trans. Swapping the rear gear is not difficult at least the ones that I have done.

The ford 9" is by far the easiest of all rear gear swaps but I am sure you have the big boy rear on those heavy duty trucks. I have swapped many ring and pinion gears on GM cars 10 bolt 12 bolt cars as well as corvette centers. from the 2.73 to a 5.13 gear it is a CHEAP and easy mod to do yourself or get done for you. Changing the rear gear means a WORLD of difference in engine RPMs do your math tons of online calculators out there check out Hot rod sites for one If you have a truck with decent power and torque you should have no problem if you are an average driver with a weekly load in a non mountain area

[slowmover]

AUTOMETER Diesel Tach Install Schematic

[JacobAziza]

Originally Posted by slowmover

AUTOMETER Diesel Tach Install Schematic

Oh man!!
I really appreciate the effort.

Won't work for me though - I removed my alternator months ago, in pursuit of better mileage!

I tried making one from a bike cyclometer and a permanent magnet, but had a lot of trouble getting the magnet to not fly off at normal speed, and getting the bracket to align and stay aligned, and eventually gave up.

[slowmover]

Then look at TINY TACH.

Thanks for the correction. I didn't measure the frontal area with any great accuracy, just a tape measure and some quick estimates so I would not be surprised if it is off. I've played with measuring Cd and Crr a bit more since originally posting this instructable and other experimenters have picked apart and tweaked the spreadsheet for their own uses so I'm 99.9% confident there is not a mistake in the spreadsheet.

[JacobAziza]

Originally Posted by slowmover

Then look at TINY TACH.

Now that is interesting. Albeit expensive. I think I'll try my method again before I spend so much.

[Milwaukee]

update?

Been drive my 87 F250 oh boy it worst on economy. Only got 16-17 mpg most times. WORST 11 that when it have leak and idle for 2 hours due snowstorm here. It been 20-30oF here.

It seem it smoke black on accelerator or under load. Suspect PO turn up the injector pump.

Temp Gauge never get up it barely creep to pass BIG white mark then drop. It got up to little closer to N when it was 70oF. Going to remove fan clutch and belt for ac compressor.


Could you tell best tip you done to truck and improve much economy.

[comptiger5000]

Milwaukee - As far as the not warming up, try replacing the thermostat. Also make sure the fan clutch isn't locked up, or convert it to an electric fan. I wouldn't drive with no fan, as if you ever get stuck in traffic, you're screwed.

[JacobAziza]

Before I removed the clutch fan (and replaced it with electric) and added the grill block, mine never got beyond the lowest part of the "L" of the L------H temperature gauge either.

You asked me the same question before. I still say driving slower made the single biggest difference.
Looking back at my fuel mileage log on EM over the past 2 years, no one thing stands out as making a hugely dramatic difference.
1983 Ford F-250 Gas Mileage (Big Orange Work Truck) - EcoModder.com
Its been gradual incremental improvements from each step, with the exception of my first tank after reading the article on Wayne Gerdes in which I first learned of the concept of "hypermiling".
In terms of combinations of things, did removing all the engine belts (fan, alternator, power steering, and vacuum pump) help more or less than the aero changes (grill block, underbelly panels, wheel well skirts, and tilted tonneau)? I have no idea, as they were all incorporated together haphazardly as my ecomodding hobby grew.

All I know is I started out getting the same mileage as you are getting now, and 2 years later I am averaging just under 30mpg for about a 4 month span.

[trooper Tdiesel]

are 1989 7.3L N\A, 1ton, 4door, 4wd, 4.11s
with the pile of poo E4OD auto trans.

pulled 21.9 mpg once years ago, in yellow-stone park at 45mph.
17/19 at 55 with stop lights is more common.

its right about 8,500lbs full of fuel (65 gal) and two people.


in comparison i must say 28+mpg is quite impressive for a F250
the closest ive ever heard of to that number was a 2wd L\B extra cab with the 3.55 and a O\D 4sp. pulling 24 or so at around 55/60

he ordered it from the factory to get that combo, he wanted a 1ton with out dully rear tires and ordering it was the only way to get a ford 1ton with out being a dully in the 6.9L years.
do to this, the truck says F250 on the side but its springs, axils, trans ECT are all 1ton spec