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Discussion Starter #1
First off, hi yall, I'm new here, and a recently new owner to the 6.0 (made a mistake a bought a 12v first), but anyway......

I've got an 04 6.0 with 35's and 3.73 gear and now power mods and I'm only gettin about 13mpg if I'm lucky in the city, and MAYBE 13.5 on the highway (and this is all unloaded). I know that these trucks get AROUND 16 stock and I'd like ot get close to that before I start dumpin money into it for intake, exhaust and a programmer, so basically my question is, do any of y'all have this setup (35's with 4.56s) and if so what kind of mileage are y'all seeing both highway and city? thanks for any info.

--Ryan
 

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Sumo Blue
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4.56's are going to be too steep for 35's.

How many miles do you have on your truck? If the miles are really low, you'll slowly start to see the mpg increase as you put more miles on and the motor breaks in.

My truck came stock with 34's and I opted for the 3.73's. I was seeing about 15-16 mpg in combined city and highway driving. I added a 4" turbo back exhaust, a SCT, and an intake and I've been averaging 16-17 mpg in mixed (city/highway) driving and over 18 on the highway.

If you really want to re-gear, I'd go with 4.10's and no higher than 4.30's.

Just my $.02 and hope it helped.



--Snake
 

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Discussion Starter #3
Snake said:
4.56's are going to be too steep for 35's.
How many miles do you have on your truck? If the miles are really low, you'll slowly start to see the mpg increase as you put more miles on and the motor breaks in.
My truck came stock with 34's and I opted for the 3.73's. I was seeing about 15-16 mpg in combined city and highway driving. I added a 4" turbo back exhaust, a SCT, and an intake and I've been averaging 16-17 mpg in mixed (city/highway) driving and over 18 on the highway.
If you really want to re-gear, I'd go with 4.10's and no higher than 4.30's.
Just my $.02 and hope it helped.
--Snake
I've only got about 67K on the truck right now, should the motor be broke in by now? Thanks for the info.... I just didn't think that goin from 3.73s to 4.10s would make a big difference, but that's why I'm askin you guys.
--Ryan
 

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Life is good
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Don't quote me on this but I thought ford motorsport made a 4:30 gear, thats what i'll be looking for in the near future.
 

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Sumo Blue
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Yeah, at 67k mi you're definitely broken in :Thumbup:

--Snake
 

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Discussion Starter #6
Snake said:
Yeah, at 67k mi you're definitely broken in :Thumbup:

--Snake
That's not what I was wantin to hear. :damnit And I was gonna try and stay away from Ford Motorsports for the sheer fact that they're proud of their stuff. I wonder if anybody else has any experience. I sure hope so. haha

--Ryan
 

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umm 4:10 gear is pefect for a 33" tire and 4:56 is good for a 35" tire those are the gears we allways matched up when we build rearends going in to a offroad rig.... and the speedo is usually very close to stock.. just my .02
 

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Texas XC Quad Racer
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My truck, 38" tires and 4.56 gears, I get 15.5 mpg on the highway and 14 in town and an SCT programmer

My truck, when I had 35" tires and stock 3.73's, I got 20.7 mpg on the highway and 18 in town and an Edge module.

I run 4.56's and they're as low as I'd want with 38's, in fact, I'd rather have 4.30's. Reason I went with 4.56's is in case I want 40's in the future. 35's with 3.73's are a perfect combo, just a little hard on an auto trans. I would go with 4.10's at most with 35's unless you plan on going bigger. These trucks mpg's are affected by rpm more than tire size, IMO. The torque these things produce don't notice the tire weight as much, mileage wise, as it does keeping the revs way up there.
 

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Discussion Starter #9
thanks for the info moose and sredish..... now I've got some decidin to do... my main reason too is I'll be towing my rock crawler often long distances, and thru mountains and such, and the torque would be nice for that.... dang, now I'm torn.

--ryan
 

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i would do the 4:56. I had them in a jeep years ago with 35's and they where fine. My current suv (G500 mb) has 4:38 gears and 31 tires. does ok in town but truns some RPMs at 80.

Ford does make 4:30 gears, they come in the big bundel tow package.

Depending on price i would go with more gears. Its better to have to much gear and run a little larger tire next go around than to be undergeared and want more power.
 

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Anytime you get the 6.0 above 2K RPM's your mileage will be bad. It is a steep curve from that point on, the more above 2K, the worse the Mileage, just like sredish said.

I have two road trips I make regularly, both about 180 miles, pretty much the same terrain, one is at between 60-65 MPH with about 8K in tow with several stop lights, and the other is 75+ MPH unloaded, all highway. I see about 1 MPG better on the loaded trip, and I believe that is due to the RPM's I am running at 60-65. Those findings were with my 33's.

I now have 35's with 3.73, and I am seeing about 1 - 1.5 MPG better with the 35's on the 75+ unloaded trip, because I am turning less RPM at the same speed, at least I believe that is the reason.

Because of DJ's Tow/Economy tune, and my new 35's I am averaging 2-3 MPG better overall than I was before making both of those changes.

I am not changing my gears, and if I was you I wouldn't go any higher than 4.10, unless you are pulling some real heavy loads.

Hope that helps...
 

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LokiWolf has it right on.
Be careful comparing these trucks to your wheelers. They're nowhere near the same animal.
Once I figured out that if I kept it under 2K RPM's it would get better milage, it made all the differance in world. I went from around 15 on the highway to 17 and that's right at 2k, cuz I can't stand going any slower.
My tires are still stock, but another guy I know was running 3.73's with 37's and towing his rock crawler through the hills to Rubicon and it did it with no problem. He barely knew his rig was back there.
I would definetly not go any lower gearing than 4.10.
Good luck
 

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I stewed on, should I go with 4:30's or 4:56's for months. I pull a 17k toybox and I decided that I wanted to save the tranny and F/R ends and went with the 4:56's. I get with 50/50 driving on 37's 14.5 day in and day out, highway I see 16 at 2000rpm (66mph) unloaded. I run the 5X on 100hp setting and have 4"TB exhaust system. If I had a trailer that weighed under 12k I would go with 4:30's and if I were running 35's and not towing much 4:10's.
.02
remember that you may never see a your money back in fuel saving but you will see your power in the "fun zone" oh ya save some money for new tires!
 

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Discussion Starter #14
sweet, thanks guys. I think I'm gonna go with 4.10s. b/c I'll be towing my rock crawler often during the summer plus other toys.

--Ryan
 

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Good choice, I think you will be happy with that.

Ray
 

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Discussion Starter #16
it may be a while b4 I regear, due to some recent money issues, but I'll update when they get it with the results.
--Ryan
 

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Suck,Squish,Bang,Blow
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I run 4.30's with my 35's. i tow heavy every so often. It is the equivalent to having a 3.90 on stock tires. Right in between the 3.73 and the 4.10 on the 350's. acceleration ..theres a big difference compared to the 3.73. MPG The last time I checked was jan 2nd on winter fuel, the bed was loaded enough to take out the rake from my lift. I was pacing others at 78-82 mph ( my speedo is corrected) and I did 20.34 mpg hand calculated. the 4.30s make it easy enough on the trans to help keep it alive. I could feel it in the trans b4 the gears on a stock tune. Also the effective 3.90 ratio does help with the mass of the tires. Bigger tires not only weigh alot more but the weight is further out and yes IT DOES have an effect on acceleration, braking and economy with tires alone. The lower ratio will help in the city and be less help on the hwy. I do well enough and my foot is always in it heavy.
 
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