MPG
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MPG
Just bought a 99 F350 with 6.8 v10. Dont know much about v10 but from what i have been reading it should get a litle better MPG than 6 or7. Now I know this truck has a 10" lift with 38x15.5x20 tires and I dont think it has been modified any. The speedo is off by 10 mph.
Like I said I dont know much about v10 or truck for that matter so I dont know yet what gear is or if it is 2 or 3v v10. Anyway is there things i should check or do to get at least 10 MPG ?
Like I said I dont know much about v10 or truck for that matter so I dont know yet what gear is or if it is 2 or 3v v10. Anyway is there things i should check or do to get at least 10 MPG ?
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Joined: Nov 2009
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From: Roseville, CA
99 f250 v-10 here with 167000 on it and I get an average of 10. All stock with lots of weight in it. You said your speedo is off? That should also make your mileage be off as well. Maybe you are getting better and do not know it? I know on my Dodge I can use superchip and modify the speedo for the tires. There has to be a shop that does that for pretty cheap. Maybe AAA does it at their work stations. Seems like a safety thing that they would do.
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From: Middleville, MI
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Joined: Oct 2009
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From: Rogue River, Oregon
I'd bet that once you get your speedo re-calibrated you'll find you are getting at least 10mpg, although if the truck has 3.73 gears the engine would be laboring with those tires. If it were me, I'd look into a set of 4.56 gears to help out with the larger tires.
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Thanks for the thoughts. I didnt think about the miles being off as well as speedo. I did see some place could calibrate and adjust for tire size but not sure about 99. It also has flowmaster exaust thought about putting straight pipes on it. Do you think that would help or is that a bad idea?
How do I find out if it has 2 or 3v v10? I cant read tag on rearend to see what gear it has and didnt see code on tag in door. Is there any place else to find out what gear it is?
How do I find out if it has 2 or 3v v10? I cant read tag on rearend to see what gear it has and didnt see code on tag in door. Is there any place else to find out what gear it is?
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Posting Guru
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From: Rogue River, Oregon
All pre-05 V10's are 2v and you should have a sticker on the door jamb to tell the axle ratio as well as if it's a limited slip or not. If not take your vin# to the dealer and he can look it up for you.
You Keep What You Kill
Joined: Dec 2006
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From: Huntersville, NC
The 10" lift kit and 38x15.5R20 tires are going to kill your MPG's. You should seriously consider re-gearing the axles to a minimum of 4.56 gears or even better 4.88 gears. You can use the link below to determine which gear will provide you the best RPM's. Your truck should have a "Transmission High Gear Ratio" of .72 with the automatic transmission.
RPM Calculator
RPM Calculator
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From: Rogue River, Oregon
my '04 has 3.73's and while it gets 14-15 easy on the freeway, I would like 4.10's better and 4.30's would allow me the choice of bigger tires down the road without fearing the expense of swapping gears.
