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Senior Member
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454 Posts
Discussion Starter #1
Do the OBS trucks tend to get better fuel mileage than the superduty trucks, regardless of what season it is? I had a 97 F350 with intake and exhaust and I was getting 16 to 17 city and 20 to 21 highway not towing or hauling. I don't have that truck anymore. I have 99.5 F350 6wheel dump truck and only seems to get 10 to 12 city and 15-16 on the highway not towing or hauling. Seems like it uses more fuel than the OBS trucks. I don't know why same engine, same size tires, same tranny same gear ratio. It is bone stock with the acception of a DP tuner chip with 60 tow and 80 enconomy settings. I only noticed a 1 mpg gain in the econmy setting and I baby the throttle. I am not heavy on the foot at all. Does the split shot injectors make the truck have poor fuel economy, vers the single shots in the OBS trucks? Anyone got any answers for me?
 

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Junior Member
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645 Posts
The OBS trucks are generally better on fuel. The obs trucks are lighter, and have single shot injector that flow 90cc of fuel. The SD have split shot injectors that flow 140cc's.

IMHO the weight make a big difference
 

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SRW Cartell #27
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487 Posts
The OBS trucks are generally better on fuel. The obs trucks are lighter, and have single shot injector that flow 90cc of fuel. The SD have split shot injectors that flow 140cc's.

IMHO the weight make a big difference

i have a 95obs that gets 19MPG (single cab 2wd) and a 99.5 that gets13-15 (extended cab 4x4 with larger tires than stock). Hayjay is right the weight is huge difference.
 

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Senior Member
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442 Posts
I heard every 100lb of weight loss you gain 2% fuel economy.

I've got a F350 with a dump, dually like yours. Weighs about 9500lb empty. Hopefully by the end of this year I'll go aluminum flatbed and lose over 1000 lbs.

Should make a difference.
 

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Senior Member
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454 Posts
Discussion Starter #5 (Edited)
Well she's got the stock torque converter still in her so I wonder if upgrading it to a tripple disk with lower stall will help it. Planning on adding an intake this spring.
 

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Junior Member
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645 Posts
Well she's got the stock torque converter still in her so I wonder if upgrading it to a tripple disk with lower stall will help it. Planning on adding an intake this spring.
I have a low stall max, billet, triple disc, from Precision of New Hampton. It is about $500. The max low stall lowers the stall speed 700 rpm, It makes a huge difference if you haul or plow.


here is a link

http://www.gopnh.com/Ford-Heavy-Duty-Torque-Converters.cfm
 
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