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Discussion Starter #1
Hello all,

We are downsizing and I am trying to determine what truck config to get to replace my F350. I am seriously considering the F150 Supercrew 4x4 with eco boost.

Plans in the future might be a small toy hauler but the next 16-24 months 70% will be driving around town (real estate broker), 25% pulling a trailer with a RZR and/or gold wing and in the future 5% pulling some type of lightweight toy hauler with RZR or wing in the back (GVWR of 9600 or less probably).

If I configure the truck for max tow then I need 3.73 gears. It doesn't seem to matter about 5.5 vs 6.5' bed though. From the Ford towing guide it seems the difference in the 5.5 vs 6.5 bed only adds the larger 36 gallon tank vs 26 for the 5.5' bed. The 5.5' bed actually has a 200lb GCWR of 11200.


So the question is, when not towing what type of MPG hit will I get on the 3.73 over the 3.55?


Any advice appreciated!
 

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If you will be towing I strongly recommend the MaxTow package that gets you the 3.73s plus a better hitch, tranny and oil cooler, radiator, brake controller, towing mirrors, and a little more cargo capacity. It is totally worth it imho.

The difference in economy will be minimal between the 3.55 and the 3.73. I doubt you would even be able to tell the difference in economy.

I have the 3.73s and regularly see over 22 on the hwy and average around 17 in the city.

Regards,

SPPD
 

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Hello all, We are downsizing and I am trying to determine what truck config to get to replace my F350. I am seriously considering the F150 Supercrew 4x4 with eco boost. Plans in the future might be a small toy hauler but the next 16-24 months 70% will be driving around town (real estate broker), 25% pulling a trailer with a RZR and/or gold wing and in the future 5% pulling some type of lightweight toy hauler with RZR or wing in the back (GVWR of 9600 or less probably). If I configure the truck for max tow then I need 3.73 gears. It doesn't seem to matter about 5.5 vs 6.5' bed though. From the Ford towing guide it seems the difference in the 5.5 vs 6.5 bed only adds the larger 36 gallon tank vs 26 for the 5.5' bed. The 5.5' bed actually has a 200lb GCWR of 11200. So the question is, when not towing what type of MPG hit will I get on the 3.73 over the 3.55? Any advice appreciated!
I have a 36 gallon tank and a 5'5" bed so not sure about the bed vs gas tank size.
 

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I also have 36 gallon tank with 5.5. I'd say max tow package (3.73) as well. You may not need the full capacity but the additional components will improve the towing experience.

I also experienced pretty good fuel mileage with 3.73 before mods.
 

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Max tow 4X2 with 6.5 bed gets you a 26 gal tank......go figure...I like mine a lot after one year. 04 diesel never had one problem in 9 years. Like the quiet and power. Tows 8500 with no trouble.....
 

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My truck is still quite new (only 3,000 miles) so my engine is quite tight, but I get similar mileage to SPPD on the highway with 3.55s. But I also have 4WD and my "highway" has been all mountain driving too. 4WD supposedly is 10% less efficient than 2WD and I would think I could get 10% better if I was travelling on "flat land" instead of mountains. I do have the Tow Package available on the XLT trim with Super Cab.

But, if I was towing a lot, especially a large trailer, I would probably prefer 3.73s ... if only for less strain on the engine and transmission due to the mountainous region I live in.
 

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I have a '13 with max tow. I average prob around 17 with it. It gets 15 to 17 in town unloaded, and 15 to 20 on the highway running 75 depending on conditions. It is the most finiky pickup I have ever owned in reguards to mpg vs. conditions. Keep it at or under 65 and I get 19+ all day long. I have 9500 miles on it and the fuel economy started getting better around 8k. It has absolutely pulled everything I have put behind it, from a 4500 lb boat (960 miles round trip) to a 10,000 lb skid steer and trailer setup (350 miles round trip). When pulling I prob average around 9.5.

I have been told that the 3.73 gear will be around 1mpg worse than the 3.55, but I wouldnt change my 3.73 for a 3.55. Hope this helps!
 

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Discussion Starter #8
I have no idea how they decide what tank to put in now. I've seen both bed versions with the 36 gallon tank.
 

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I have a 2013 Screw loaded with every option.. 6.5ft box. Bigger gas tank and 3.55s hwy mileage is 20mpg and average 600 + miles to a full tank. Wish I had the 3.73 gears.. cause I have 35s tirws now...
 

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You will not tell the mpg difference between 3.55s and 3.73s. I dont even think you would see a difference between 3.55 and 4.10. Browse through the fuel mileage thread, you will see there isn't really a correlation between rear end and mileage. The biggest factor is your right foot.
 
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I have the 3:55s, I really wanted the 3:73, because the power is noticeable. When I test drive both trucks the 3:73 spun the tires while I was moving, where the 3:55 aren't as much trq.
The only reason I didn't get Max towing pckge was, I didn't like the huge mirrors. For the amount of normal driving, I wouldn't need them.
 

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I have no idea how they decide what tank to put in now. I've seen both bed versions with the 36 gallon tank.
My build sheet shows "optional 26 gallon fuel tank" I assumed the 36 was standard.

SPPD
 

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Discussion Starter #13
For those of you with 3.55 if you tow close to the limit of your rating do you lock out 6th gear or can the truck handle it? Same question for 3.73 owners. I understand from my reading that the 3.55 does a pretty good job of towing 5-8000lbs. I am curious HOW the towing experience is. Example, with my F350 8000 lbs you know its back there but it will tow in overdrive with no issues at all. 20,000 lbs it will drop out of overdrive quickly on any type of hill but on flat ground at 60 mph will hold overdrive.
 

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I once towed a load of steel that was right at my towing limit (11,000lbs~) and it did great. A couple short climbs, it did drop out of overdrive, but did not struggle. On flat ground it held 6th no problem. I never lock out gears, I just leave it in tow/haul.
 

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I have the 3:55s, I really wanted the 3:73, because the power is noticeable. When I test drive both trucks the 3:73 spun the tires while I was moving, where the 3:55 aren't as much trq.
The only reason I didn't get Max towing pckge was, I didn't like the huge mirrors. For the amount of normal driving, I wouldn't need them.
You could've gotten the max tow w/out the mirrors.

For those of you with 3.55 if you tow close to the limit of your rating do you lock out 6th gear or can the truck handle it? Same question for 3.73 owners. I understand from my reading that the 3.55 does a pretty good job of towing 5-8000lbs. I am curious HOW the towing experience is. Example, with my F350 8000 lbs you know its back there but it will tow in overdrive with no issues at all. 20,000 lbs it will drop out of overdrive quickly on any type of hill but on flat ground at 60 mph will hold overdrive.
Towing with the eb is unlike towing with any other 1/2 ton truck, that is for sure. When I tow close to my eb's limit (11.3k lbs) depending on where I'm going I'll limit out 6th gear, but If I'm on a nice flat stretch of highway she'll hold 6th with no issues. This was with approx 9k lbs trailer and load.

I'd definitely reccommend a set of springs or bags though. The suspension is a bit softer than I like for high loads.
 

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Discussion Starter #16
I am test driving a 13 ecoboost crewcab 4x4 with 5.5' bed and 3.55 gears overnight. I reset the mpg and after a 35 mile ride on the interstate at 75 it was avg 17.2 mph. One the return leg at 65 it was 18.7. At 75 mph rpms were 1800. At 65 they were around 1300 if I remember correctly. At 80 they were 2000.
 

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I am test driving a 13 ecoboost crewcab 4x4 with 5.5' bed and 3.55 gears overnight. I reset the mpg and after a 35 mile ride on the interstate at 75 it was avg 17.2 mph. One the return leg at 65 it was 18.7. At 75 mph rpms were 1800. At 65 they were around 1300 if I remember correctly. At 80 they were 2000.
I run right at 2000 rpms at 75/ 16mpg
 

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The difference between 3.55s and 3.73s is only 5.07%. That means "at best" if a 3.73 truck were to get 20 mpg, at best with 3.55s you'll get 21 mpg. I can tell you "driving style" can make more of a difference than the gears.

I would be more concerned that your rear-end had an E-locker or a Limited Slip differential (and not an open differential). If I were buying another new Ecoboost, I would select the truck that had most of my other "must have options" ... and I would accept either 3.73s or 3.55s - provided it was either an E-locker or Limited Slip.

6th gear is pretty tall, so there really isn't much of a differnce between 3.73s or 3.55s in all honesty. 3.31s or numerically lower is another story.

PS: I get slightly better mileage than you posted, and I have 3.55s. I get an honest 21.5 mpg measured at the pump (not the "display") ... and that was doing 65 mph on a long trip through the mountains in both directions (so their is no advantage). I figure on "flat land" (like Kansas) I might see 22-24 mpg at 65. Which I think is pretty darn good for a truck weighing close to 3 tons.

I should also add that my truck easily went up and down through this mountain highway, and rarely downshifted, even when going uphill. It held 65 easily.

My mileage has steadily got better as my engine breaks-in, and I still only have 3,500 miles. My brother is thinking of selling his Silverado now that he sees the mileage I get on the same highway he travels.

But my advice is ... find the truck you like the best, make sure it has either an E-locker or Limited Slip (E-locker is more fuel efficient btw) ... and don't worry if it has 3.73s or 3.55s.
 

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Discussion Starter #19
Great info from everyone!

Grim, the truck I am test driving is the platinum with 3.55 E-locker. There are no 3.73's around here to test drive. The closest one I can find is a bit over 200 miles away. That is why I am asking all these questions. I am one to analyze everything, sometimes to a fault. Thanks for the info on the gearing. I was in the process of actually calculating the difference. You and others have stated it is about the MPG is basically the same and the math bears that out.

Search continues.
 

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The reason Truck manufacturers offers the 3.42 and 3.55 ratios in our pickups and SUVs is those ratios offer the best fuel economy with a six-speed automatic transmission. If you want a truck that responds best to a heavy load or towing a trailer, then 3.73, 3.92, or 4.10 ratios will provide the best wheel torque at the lower engine speeds.
 
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