12 MPG? Can't I Get Any Better!?!
#47
I bought 3 new trucks in my past. 1989 F150 shorty 4.9 M5OD 2wd with 3.08 gears, 1991 F250 2wd 7.3 E4OD with 3.55s ,and a 1996 F250 SC shorty 4x4 PSD ZF 3.55s.
I always calculated my mileage for all 3 . Summer and Winter MPG were extremely different. 89 averaged about 21mpg summer/winter combined up to 28 on highway trip at a steady 70mph, heavy loaded down to almost 12mpg.
91 was a little better on fuel pulling unless I took it out of overdrive like the manual says. Averaged around 19.5 mpg , but best was almost 25mpg empty highway.
96 was almost identical to the 91 but got 27.5 on long trip empty in summer. It could pull 12,000 lbs and at 70mph, which neither of the others could.
All 3 ran at almost the same rpm at 70mph 2100.
I did all my calculations with an Imperial gallon 4.54 litres, US gallon has only 3.78 litres
Now I am married , 2 kid under 5 with a stay at home mom and a mortgage.
My driver is a 86 VW golf diesel, and the old trucks are just summer toys.
Old Fords Rule, I have 2 barns full.
I always calculated my mileage for all 3 . Summer and Winter MPG were extremely different. 89 averaged about 21mpg summer/winter combined up to 28 on highway trip at a steady 70mph, heavy loaded down to almost 12mpg.
91 was a little better on fuel pulling unless I took it out of overdrive like the manual says. Averaged around 19.5 mpg , but best was almost 25mpg empty highway.
96 was almost identical to the 91 but got 27.5 on long trip empty in summer. It could pull 12,000 lbs and at 70mph, which neither of the others could.
All 3 ran at almost the same rpm at 70mph 2100.
I did all my calculations with an Imperial gallon 4.54 litres, US gallon has only 3.78 litres
Now I am married , 2 kid under 5 with a stay at home mom and a mortgage.
My driver is a 86 VW golf diesel, and the old trucks are just summer toys.
Old Fords Rule, I have 2 barns full.
#48
Oops , forgot to throw in my 2cents on the tailgate thing.
When empty and highway commutting, all 3 trucks were slightly more fuel efficient, the 89 F150 would gain almost 2mpg, the 91 and 96 were better but just over 1mpg difference. When pulling my trailer it got worse mileage on the 96 if I put the gate down, would drop 1-2 mpg.
But it doesn't look cool when you can't advertise the FORD badge.
When empty and highway commutting, all 3 trucks were slightly more fuel efficient, the 89 F150 would gain almost 2mpg, the 91 and 96 were better but just over 1mpg difference. When pulling my trailer it got worse mileage on the 96 if I put the gate down, would drop 1-2 mpg.
But it doesn't look cool when you can't advertise the FORD badge.
#49
#50
I lurk around in the shadows on here alot more than I post............
I'd like to hear more info on the 'mythbusters' test. I must have missed that show. Did they use the SAME truck or 2 different trucks for testing, or did they do what they did when they tested the AC Vs. Windows down? For that they used a AWD explorer and a selectable 4wd one. SO, this ALONE would affect there roundy-round comparison they did as they didn't test for a decline in mileage, but which one did more laps. I've never tested the diff. between the 'gate up or down, but was raised to ALWAYS drop it do to, "wind cresting the cab and ramming into the 'gate"? It just seems logical to me.........
Hmmmmm........I just went back and read that linked article, sounds like a good one to sell tonneau covers and canopies......but the leaves/paper cup comment was worth thinking about.
I'd like to hear more info on the 'mythbusters' test. I must have missed that show. Did they use the SAME truck or 2 different trucks for testing, or did they do what they did when they tested the AC Vs. Windows down? For that they used a AWD explorer and a selectable 4wd one. SO, this ALONE would affect there roundy-round comparison they did as they didn't test for a decline in mileage, but which one did more laps. I've never tested the diff. between the 'gate up or down, but was raised to ALWAYS drop it do to, "wind cresting the cab and ramming into the 'gate"? It just seems logical to me.........
Hmmmmm........I just went back and read that linked article, sounds like a good one to sell tonneau covers and canopies......but the leaves/paper cup comment was worth thinking about.
Last edited by little Loopie; 03-11-2006 at 01:53 PM.
#51
#52
The tailgate thing:
Think about an airplane wing. The shape of the wing has a longer surface over the top which makes the air speed up to pass over it. This creates a big pressure drop, which in turn creates lift over the wing and the plane rises.
The roof of your pickup is the top of the wing. As your speed increases the air rushing over the cab causes a negative pressure behind it, which tends to pull you backwards. Having the tailgate up maintains a rolling cushion of air in the bed, out of the overall airstream. This air cushion is affected by but not a part of the overall airstream. Dropping the tailgate bursts this bubble and the whole bed then becomes a mass of turbulance that creates a greater negative pull on the truck.
Try this: Before your next wash job, sprinkle a pound of flour all around into the bed and have someone drive your truck with the tailgate up. Watch what the flour does. You will see the air cushion in the bed. After you observe the pattern, stop and lower the tailgate and see what it does then.
(Keep all your windows closed for both tests.)
Think about an airplane wing. The shape of the wing has a longer surface over the top which makes the air speed up to pass over it. This creates a big pressure drop, which in turn creates lift over the wing and the plane rises.
The roof of your pickup is the top of the wing. As your speed increases the air rushing over the cab causes a negative pressure behind it, which tends to pull you backwards. Having the tailgate up maintains a rolling cushion of air in the bed, out of the overall airstream. This air cushion is affected by but not a part of the overall airstream. Dropping the tailgate bursts this bubble and the whole bed then becomes a mass of turbulance that creates a greater negative pull on the truck.
Try this: Before your next wash job, sprinkle a pound of flour all around into the bed and have someone drive your truck with the tailgate up. Watch what the flour does. You will see the air cushion in the bed. After you observe the pattern, stop and lower the tailgate and see what it does then.
(Keep all your windows closed for both tests.)
#53
Originally Posted by Bdox
The tailgate thing:
Think about an airplane wing. The shape of the wing has a longer surface over the top which makes the air speed up to pass over it. This creates a big pressure drop, which in turn creates lift over the wing and the plane rises.
The roof of your pickup is the top of the wing. As your speed increases the air rushing over the cab causes a negative pressure behind it, which tends to pull you backwards. Having the tailgate up maintains a rolling cushion of air in the bed, out of the overall airstream. This air cushion is affected by but not a part of the overall airstream. Dropping the tailgate bursts this bubble and the whole bed then becomes a mass of turbulance that creates a greater negative pull on the truck.
Try this: Before your next wash job, sprinkle a pound of flour all around into the bed and have someone drive your truck with the tailgate up. Watch what the flour does. You will see the air cushion in the bed. After you observe the pattern, stop and lower the tailgate and see what it does then.
(Keep all your windows closed for both tests.)
Think about an airplane wing. The shape of the wing has a longer surface over the top which makes the air speed up to pass over it. This creates a big pressure drop, which in turn creates lift over the wing and the plane rises.
The roof of your pickup is the top of the wing. As your speed increases the air rushing over the cab causes a negative pressure behind it, which tends to pull you backwards. Having the tailgate up maintains a rolling cushion of air in the bed, out of the overall airstream. This air cushion is affected by but not a part of the overall airstream. Dropping the tailgate bursts this bubble and the whole bed then becomes a mass of turbulance that creates a greater negative pull on the truck.
Try this: Before your next wash job, sprinkle a pound of flour all around into the bed and have someone drive your truck with the tailgate up. Watch what the flour does. You will see the air cushion in the bed. After you observe the pattern, stop and lower the tailgate and see what it does then.
(Keep all your windows closed for both tests.)
Mike
#57
Explain the tire size fuel economy please
Explain the tire size fuel economy please for me.
Originally Posted by dale gribble
Oh yeah- don't foget to take into account tire size... Even if you went from a 235/75R15 (28.8" diameter, 90.72" circumferance) to a popular replacement tire that most people put on- a 31x10.50R15 ( most measure ~30.5" diameter, 95.61" circumferance)... That's a 5.6% difference.
12 MPG * .056 difference= .67MPG difference. That brings you up to almost 13mpg! for free!
If you need to know the tire size your truck shipped with, it's in the door jam. Do the math if you have done a tire size change.
12 MPG * .056 difference= .67MPG difference. That brings you up to almost 13mpg! for free!
If you need to know the tire size your truck shipped with, it's in the door jam. Do the math if you have done a tire size change.
#60