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What are the best MPG mods you guys have seen with the 6.4L? I have an '08 6.4L dually with SCT tuner & DPF/Cat delete and my MPGs went from ~10.5 to 14. Any suggestions on further improvements?
 

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Other then changing gears, that's probably about as good as your gonna get with a dually. Due to gears and additional tires, the dually's take a bigger hit on MPG then their F250/F350 SRW brothers.
 

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I have to agree with Shaun. Gearing is killing you.

Custom tuning may help a little bit.
 

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What for gears do the duallys have and what should he go to?
 

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I found the right foot has a lot to do with it
Now don't use as much radio power when driving.
Also I have found that my programer keeps the engine at higher temps while city driving saving enegy by the fan controling temperature and a hot diesel is much more efficient.
 

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I believe they are like 4.88, you could go lower but keep in mind, changing your gear ratio will affect your towing capacity.

As a comparison, the F250 comes with 3.73 std.
 

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What for gears do the duallys have and what should he go to?
I believe they are like 4.88, you could go lower but keep in mind, changing your gear ratio will affect your towing capacity.

As a comparison, the F250 comes with 3.73 std.
Most DRW F-350's come with 4.10 gears. I think a few MAY have been equipped with 4.30's, but that isn't standard. The only DRW trucks with 4.88's are F-450's and F-550's. After 2008, standard for F-250's became 3.55's and I think SRW F-350's were both 3.73 and 3.55's.

My guess is he has 4.10 gears. :nod:
 

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Whoops, my bad, he has the F350. I thought I read he had the F450. Good catch Jeff. :thumb:
 

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My DRW F350 has the "tow boss" package, part of which were 4:30 gears. So I'm guessing DRW trucks without the tow boss package have 4:10 gears
 

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I would go with a custom tune from KEM, the 250 tune is very good for fuel economy. It did a very big difference on mine. From seeing 12mpg stock to 19-21mpg with the tune, it's a huge improvement! And for only 75$, it worth every penny!
 

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Ford Performance Specialties claims that with a DPF delete and Gear Vendors OD kit you can get 23mpg. The parts run about 3500 new but that's a hell of a hookup and you can split all the gears except 4th. That's badass IMO. Good luck
 

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My brother's '08 F-350 DRW had 3.73s. Confirmed on the window sticker. I don't know if 3.73s or 4.10s were more common though.
 
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