EcoBoost 3.31 Owners...Any Regrets?
 

Just want to hear from the EcoBoost owners with 3.31 gears...do you have any regrets not getting another ratio?

From the Ford Canada site, the EcoBoost supercrew with 3.31 gears can tow 9,100lbs. The 3.55 tows 9,500lbs

Honestly...either of these numbers vastly exceeds what I will foreseeably tow. I'll be towing some dirtbikes, a few loads of gravel in a 1yard trailer, etc.

Mostly the truck will be used lightly loaded. Day trips to go fishing. Logging roads. Hauling a bed load of alder firewood.

I want good economy more than I want a rocketship. And I want the EcoBoost for it's quiet operation.

Thanks!

I'm not very familiar with gears. I have a 2013 ecoboost with the 3.55

I wonder whats different from 2012 as 3.31 axle had a limit of only 8100 lbs. I seen 2013 upped the tow rating to 9200 lbs so I wonder if it had something to do with the upgraded intercooler.

Mines a 2011 with 3:31's and like you, didn't see myself pulling much over the 8200 rating. 40000 km and averaging 18 mpg overall. Last two weeks I've been working 100 km away. On the 200 km trip daily, I've been averaging 20 - 22 mpg per tank. All secondary and tertiary roads at 55 mph. Very hilly. Haven't pulled any weight over 3500 lbs but my tool trailer has a lot of frontal area and still pulls with ease.

i actually have the 3.73's, because that was all that was available in an fx4 trim.

i'll say this, with the new 6-speed transmission i am in 3rd gear before crossing an intersection from a stop. and with the torque of the ecoboost i have no need to cruise 65mph at the rpm's it sees. it is nice when towing, but then again, i could just lock out 6th gear if it was needed while i towed because i had lower gears.

turbo's love low gears. lets the turbo's spool and load. i say go for it. i plan to on my next one.


edit:
when i say "low" gears, i mean low numerically...

There's very slight mileage differences between the 3.15s and 3.73s. I'd go 3.73 for the performance. Or if you want, I'll swap rear axles with you and you can have my 3.15s.

Thats what nice about the F150 lineup, they give you more configurations than any other pickup. I think the 3.15 are better highway mileage to the 3.73/4.10 which are towing monsters. If your not towing but 1/2 capacity of your truck then you got the right gears. I tow a 21ft bass boat all year long so the 3.73 max tow was the truck for me. I liked the low end grunt when at a traffic light to keep up with traffic and not be the knucklehead everyone is screaming at becuase it takes too long to get up and go and there looking to pass me because i'm the granny in the fast lane. I wish my truck got the 19-23 miles the lower rears gets in mileage but it is all a trade off to the needs of the owner.

I've got a 2013 ecoboost 4x4 screw with the longer bed and the 3.31 gears. Got over 3000 miles on it now. Mainly daily driver stuff, no towing, 60-70 miles a day some hills and right now it's showing 18.0 mpg life time. At 2k miles it was 17.8 so it is increasing still. No problems, no concerns with power or anything. (These are all winter mileage / gas numbers as I bought my truck at the end of November.)

Just be sure there aren't future plans to buy a bigger trailer or anything....

Lots of guys on here buy trucks, then realize they aren't what they wanted or needed and they end up changing trucks again.

My 3.31
 

I've got the 3.31 in my '11 eboost scab with 21K miles. I get 21-22 @ about 65-70 on the highway. Everything is stock but I'm about to pull the trigger on a set of 295/18's and Bilstien 5100's. I wonder how that will change my torque, power and mileage? Anyone else have this setup or any thoughts? I really don't tow much. Was also concerned if I might have to eventually switch out diff gears but not sure to which one. :cowboy:

Awesome, thanks for the reply. This is what I was thinking, but every other "3.31 vs 3.55 vs 3.73" thread has all the guys who haven't personally experienced them weighing in.

Great, thanks. That's the type of economy I'd like to get. Glad to hear that somebody else is getting that sort of economy.

Size the truck to your needs. That's my only advice.

My 2012 SCAB has gotten an average of 18.1 mpg over the 1000 miles I've had it. Basically, 2 tanks of gas :)

This is probably 70% hwy, 30% city. On one trip of about 100 miles on country roads with no (or maybe only 1-2) stop signs, Set cruise at 55mph and I've seen as high as 24 mpg.

I'm following the old adage (which I've seen posted here many times): better to have it and not need it, than to not have it and need it.

So that's why I went with the 3.73 on my order. Plus, I think I'll like the added grunt off the line.

With the EB and all its gobs of low end torque I don't think there is much reason to get the high ratio gears. You have a 6 speed gearbox no matter what so I am pretty sure it should be able to find a gear that fits its needs.

I ordered mine with 3.55s because I knew I was going to put larger tires, but I probably could have got 3.15 or 3.31's and not been in any way negatively effected. I tow big stuff and load up the bed on occasion like the OP and I don't forsee the 3.31's being a problem.

I have the longbed 2011 ecoboost with 3.31 gears and my father has a 2012 regular bed with 3.73 and max tow both super crews. we have toyed around a bit and from a stop light my truck will takes his every time and from a 50mph roll he just edges me out. I know turbos like loaded engines so i reach full boost before him and get more power from the engine sooner. we both like our trucks mph im 1-2mpg better than him highway in the city we are the same. I never tow more than 5k lbs so i would never need lower gears.

The only regret I have is the silly arguments over gears. I chose 3.31 because for my needs it works. It's mostly a daily driver. I tow a tt about 4000 miles a year (6,000 lbs). Lifetime mileage with 23k is about 16.5 according to cluster. If I got another I might go 3.55 but maybe not. Anyway, with the EB it has the stones to do all I Ned and more. I just down shift and instant lower ratio.

3.31 gears
 

Great info here. So with my 3.31 ecoboost I shouldn't have any problems with power or mileage if I change out the stock 275/18's to a 295/18's or even a 305? Thanks again ;)

Awesome info! I'm set on the 3.31 gears from this thread and others. I'll update in a few months when I get the truck!

I have the 3:15 in my 13 Eco and love it. My son has a 12 with 3:55 and I can't tell any difference in acceleration or highway driving. But neither one of us tows anything, so can't comment on that part.

Just made the first tow today with my 4x4 eco with 3.31. 2 round bales of hay on a old heavy dual axle trailer. Figure 4000 lbs.

Very light but it had plenty of pep and pulled smooth.

Just so you know, the 3.31 gear takes away much of the Ecoboosts advantage over a 5.0L with 3.73 gears.

Using the 3.55 gears as a standard which torque and horsepower are referenced with, here's a break down.

http://farm9.staticflickr.com/8362/8...ebd5f89e_z.jpg
http://farm9.staticflickr.com/8353/8...a1937839_z.jpg


A 3.31 gear is 6.8% larger than a 3.55 gear meaning a loss of 6.8% torque.

A 3.73 gear is 5.1% smaller than a 3.55 gear meaning a gain of 5.1% torque.

Horsepower formula is Torque * rpm/ 5252 = HP

Ecoboost has 365 horsepower at 5000 rpms (referenced to a 3.55 standard axle). The Ecoboost has about 387 lbs of torque at 5000 rpms. With a loss of 6.8%. 6.8% * 387 = 26.316 . 387 - 26.316 = 360.684 (~361 lbs of torque). 361 lbs * 5000 = 1805000 . 1805000/5252 = 343.678 HP (344 HP). You've lost 21 horsepower with a 3.31 gear on your ecoboost.

5.0L has 363 lbs of torque at 5000 rpm. 363 lbs * 5.1% = 18.5 lbs . 363 lbs + ~19 lbs = 382 lbs. 382 * 5000 rpms = 1910000 . 1910000/5252 = 363.67 HP (364 HP).

So at 5000 rpms, the 5.0L will have 20 HP more than an Ecoboost. The lower rpm is still good but marginally better than the 5.0L and looses a lot at higher rpms.

So by getting the 3.31 option with the Ecoboost, you really lose the main benefit of the Ecoboost, and that's power. The mpg is about equal between the two so the power is the large benefit of the Ecoboost.

So if you have any choice at all, avoid the 3.31 gears.

My understanding is horsepower is what it is, gearing just determines how the transmission uses it. I'm not sure you percentile calculations are translated accurately.

I regret mine with the 3.31's. Towing an aluminum trailer with 2 utility quads it gets 10mpg. If I could have done it over I would have gotten the 3.73's or at least 3.55's. Otherwise I like the truck.

You have it wrong. Horsepower is based off of torque with the formula (Torque * RPM) / 5252 .

I used Ford's base torque ratings based on a 3.55 axle. With a 3.31 axle, you will lose torque, and with a 3.73 axle, you will gain it. A 3.31 may help with fuel economy at highway speeds with NO LOAD but you lose power.

Axle gears are torque multipliers. The Ford torque charts are from the flywheel with no torque multiplier yet.

Not all torque multipliers/dividers are taken in account, as the transmission gears, wheel size, or driveline loss. Just simplifying it with flywheel torque and axle gears (3.55 being the reference used for the base torque).

The ford charts aren't an end all as driveline loss isn't factored in, wheel size, transmission gears or axle gearing.

I was just making a comparison to show the dramatic loss of going with a 3.31 axle.

If you were soley buying the Ecoboost for power output but decided on a 3.31, you may as well go for a cheaper 5.0L with the 3.73 because your torque won't be far behind and you will have more available horespower.

Mike my only complaint about the comparison is you are using peak numbers. The benefit of the eco is the flat torque curve. Yes, the 3.31 utilizes it less effectively but the flat curve still provides a benefit over the 5.0 even with 3.31s. Especially with computer controlled shift adjustments in tow/haul mode.

In the real world, peak numbers at 5000 rpm are not really useful.

That peak of 5000 is only for the Eco so it's not peak for the 5.0L. The 5.0L will have even more power at it's peak of 5500 rpms. 350 lbs * 5.1% = 17.85+ 350 = 367.85 lbs (~368 lbs ). 368 lbs * 5500 rpms = 2024000 . 2024000/5252 = 385.37 HP (385 HP). So the 5.0L with 3.73 axle would have a geared 385 Hp, the Ecoboost with 3.31 axle would have a geared 344 Hp. That's a geared 41 Hp difference, HUGE.

The moral of the story is don't go with the 3.31 if you're after power. The Eco has so much torque, you may only need the 3.55 axle. But if you're power hungry and don't care about highway mileage, get the FX4 Ecoboost with the optional 4.10 axle and get power out the arse!!

Gearing is such a huge difference that nobody considers the transmission gearing or the axle gearing. All they look at is the engine rating and consider nothing else. That's why a Dodge Ram 390 HP Hemi 5.7L Crew Cab 4WD truck has the exact same 0 - 60 mph and 1/4 mile time as a Ford F150 360 HP 5.0L F150 Crew Cab 4WD truck. Dodges 5 and 6 speed transmissions suck with a low 3.00:1 1st gear. The rest of the gear are also taller creating less torque than the awesome Ford 6 speed transmission gearing.

I drove a 2008 F150 Screw 5.4L w/3.73 axle and it's crappy 4 speed transmission. It felt like a dog. I bought my 2010 F150 Screw 5.4L w/355 axle and it's awesome 6 speed transmission (geared LOW), and it felt like another 60 Hp and torque. The 2010 proved it provided much more power as it had a 0 - 60 time at 1 second faster along with a much quicker 1/4 miles time.

The 2010 had tons more torque because of the geared torque multiplier in the new 6 speed transmission. 6 speed trans has a 1st gear of 4.17:1 while the 4 speed has a 1st gear of 2.84:1, A HUGE DIFFERENCE!

With engine power very close between trucks, the axle gearing and transmission can make more of a difference than just the engine.

It's not your ratio. I have 3:31's and tow a tall enclosed trailer, around 3500 lbs. On windy days in hilly areas, keeping up with and sometimes ahead of traffic, I get 13 mpg +. Nice calm days I've had as high as 17 mpg.

I do want to add though, even with the 3.31 axle, you'll still have more low end torque than a 5.0L with the 3.73, you'll just lose upper RPM horsepower. So why not get the full power of the Ecoboost and stick with the 3.55, 3.73, or 4.10 to get the most out of the engine, IF YOU CAN.

All referenced off of a base torque value with a 3.55 axle.


5.0L w/3.55 axle

1500 rpm = 275#

2000 rpm = 302#

2500 rpm = 315#

3000 rpm = 327#

3500 rpm = 350#

4000 rpm = 365#

4250 rpm = 380#

4500 rpm = 375#

5000 rpm = 363#

5500 rpm = 348#

6000 rpm = 315# (Redline)



5.0L w/3.73 axle

1500 rpm = 289#

2000 rpm = 317#

2500 rpm = 331#

3000 rpm = 343#

3500 rpm = 368#

4000 rpm = 383#

4250 rpm = 399#

4500 rpm = 394#

5000 rpm = 377#

5500 rpm = 365#

6000 rpm = 331# (Redline)



3.5L w/3.55 axle

1500 rpm = 375#

2000 rpm = 381#

2500 rpm = 420#

3000 rpm = 420#

3500 rpm = 413#

4000 rpm = 413#

4250 rpm = 402#

4500 rpm = 400#

5000 rpm = 388#

5500 rpm = 352#

6000 rpm = 275# (Redline)



3.5L w/3.31 axle

1500 rpm = 350#

2000 rpm = 355#

2500 rpm = 392#

3000 rpm = 392#

3500 rpm = 385#

4000 rpm = 385#

4250 rpm = 375#

4500 rpm = 373#

5000 rpm = 362#

5500 rpm = 328#

6000 rpm = 256# (Redline)



5.0L w/3.73 axle compared to 3.5L w/ 3.31 axle

1500 rpm = -61#

2000 rpm = -38#

2500 rpm = -61#

3000 rpm = -49#

3500 rpm = -17#

4000 rpm = -2#

4250 rpm = +24#

4500 rpm = +21#

5000 rpm = +15#

5500 rpm = +37#

6000 rpm = +75# (Redline)

I think what packplant might be getting at is with the torque of the Eco coupled with 6 speed trans, you won't notice a reduction in torque or HP until 6th gear.
So as soon as it needs the added torque, it just drops a gear. The engine will still put out the same power, just requires a different gear to use it.
Am I close?

Compared to a 5.0L w/3.73, you'll get your most torque below 4000 rpms so you wouldn't want the engine to downshift to a higher rpm.

Now if you are working your way up into the gears, you'll want higher rpms to get your horsepower. You just don't want to go into passing gear from a stabilized speed to a lower torque output, higher rpm.

I've noticed after driving all 3 configurations of new gen F150s (5.4L, 5.0L, and Eco) that the shifting strategy is different for the engines.

The 5.4L and Ecoboost have their peak torque at lower rpms so the transmission is slow to downshift to lower gears and upshifts faster to get the most torque output to accelerate.

The 5.0L downshifts sooner and more gears to get higher rpms when going into passing gear from a stabilized speed. It also upshifts slower, holding the gear to climb higher in the rpms where the 5.0L makes more power.

So the shift patterns of the transmissions are tuned to the engine they are transfering power from. So I don't believe the Eco trans will downshift as easily but this actually is a good thing since the Eco makes it's power down lower.

The Eco with 3.31 will still be a better towing engine with it's low end torque but will need to downshift more often as it may not be able to hold gears as well under load with the lower horsepower.

The Eco is still a great engine it's just a shame to cripple all of it's power benefits with a 3.31 axle. The best overall gear will likely be a 3.73 but you need to go up to the Max tow package to get this or a FX4 model. The 4.10 would likely have horrible mileage and be very hard to hookup the tires with such a torque multiplier. It would be the ultimate power house if you could get the power to the ground though.

Lower gears show less on the dyno than higher gears.

I don't have experience with 3.31s but I do have 6k miles with my new work truck EB Scab 2wd with 3.15s. My previous work truck was a 5.0 Scab 2wd 3.55 and my personal truck is in my signature which is a tuned EB Screw 4wd 3.55. My new 3.15 EB work truck has noticeably more low end pulling power than the old 3.55 5.0 especially below 3,000 rpm in normal driving. The 5.0 required more throttle and higher rpms to give you close to the same pull than the 3.15 EB even with it's taller gears. Put the hammer down on both and you probably wouldn't be able to tell the difference between the two from their acceleration because it is too close to tell for most people.

The 3.15 EB work truck is not quicker than my personal truck of course because it is tuned, but it is pretty damn close from what I remember of my truck being stock. The torque pull on my personal is slightly more pronounced in stock form, and the 3.15 work truck EB is drawn out a little more which is actually better in a lot of passing situations. However, I think the inadequate problems that some of the 3.15/3.31 EB owners are feeling is not due to the gears. My personal truck was the same way when it was stock and so was a friends Screw with 3.73s. That sloshy or inadequate feeling you get with the 3.15/3.31(or even the rest of the ratio's) mainly has to do with the trucks stock shift tuning and torque converter lockup. The truck in stock form shifts too soon and the torque converter not locking up quickly makes the truck feel like it doesn't have enough power especially for a brief instant until it does lock up. Some say it is turbo lag but it isn't. My 5 Star tune fixes this and I personally do not like driving an EB any other way now. With his tune you get that torque pull at any speed or slight acceleration with quick lock ups making the truck feel as powerful as it actually is. I have other tunes that are quicker at WOT and put out more HP than my 5 Star tune but do not fix the shifting and torque converter lock up. They almost feel like a stock truck at times with that same sloshy feeling with normal acceleration until you mash the pedal down so I know it isn't turbo lag.

It is also easier to get great mpgs out of the 3.15 gears. My personal truck has gotten great fuel mileage too but I have to work at it versus just setting the cruise on my work truck it can easily getting 20-21 at 75 mph.

IMHO......If I didn't need to tow that much or needed 4wd, I would not have any regrets getting a 2wd 3.15/3.31 EB as long as it was tuned. Driving an un-tuned one is actually not that bad either, but I prefer it tuned to get rid of Ford's sloppy shifting and trans strategies. I don't think you would regret it either.

That is the comparison that mattered to me and is the reason I went eco over 5.0. I knew I lost a little on the top end with 3.31, but for me the top RPM range isn't really relevant. I wont' see 4500 RPM very often, much less 5000. I don't race or tow heavy trailers in the mountains. I won't tow near the maximum rating of #8400 (I think that is the number...) so it didn't matter to me.

I actually wanted the 3.55, but they had a good deal on the 3.31 so I checked the towing differences and decided I'd take the deal. I haven't regretted it so far.

X10 on this. I am thinking about a tune just for a shifting fix.

My 2012 ecoboost has 3.55 rear end gear, just curious what the highway mileage difference would be on average if it had a 3.15. Not a gear head here myself, so i guess the lower number gear ratio equals better mpg?

My work 3.15 normally gets around 18.5 combines and can easily do 20-21 mpg setting the cruise at 75 mph(it does it rather easily too). I have only had the truck for two months so this is all winter fuel averages and have put 6.2k miles on it so far. I am one of those people that get better fuel mileage setting the cruise because of my driving habits. I know some people may get better fuel mileage without cruise and some technique, but I don't want to have to do that all day everyday. I thought there would be a bigger difference between the ratio's on the butt dyno but it is no where near how it effects most other N/A motors. I just think this engine has too much low end power to have it play that much of a difference unloaded. Loaded with over 5,000 may be a different story. You are correct in your guess, lower number ratios(taller gears/3.15) generally get better highway fuel economy than higher number ratios(shorter gear/3.73).

Upgrade from 3.31 to 3.73
 

I have a 2012 XLT EcoBoost SuperCrew. No mods. 3.31 regular axle.

I don't tow/haul much or often. My truck is my daily driver - primarily for household stuff (landscaping supplies, home improvement supplies, moving furniture, etc.).

However, I would like to go off-road one of these days. Nothing crazy - just go down some trails or off pavement. I noticed the Off-Road package for my truck said it had the following:

• 3.73 electronic-locking rear axle
• Fuel tank, transfer case and front differential skid plates
• Off-road tuned front shock absorbers

Can anyone tell me if upgrading my truck (buying parts and installing them, not getting a new truck) to have the OEM 3.75 electronic locking rear axle is within reason to do? What parts am I looking at here, and what's the price range? I'm relatively new to pickups, so I'm not up on what conventional wisdom is. Any help or advice would be greatly appreciated. Thanks!

So I can't say I regret the 3.31. It does everything I need it to do right now. But given that I'm thinking about things I would like to do with my truck I haven't done before, I see the possibility for some regret in the future. :unsure:

Any regrets? No none... 12 screw 4x4 Eco 3.31

Truck pulls hard if I need it to.
Hauls anything I have needed very easy ( only about 3500lbs) so far
I can smoke the tires off the rims if that's really what I wanted.

Normal everyday driving you won't be disappointed. Just know what you need, different from what you want. I knew I only needed 3.31 and I wanted 3.31.

Love my 13 Eco screw 4x2 with 3:15 gear. Average 18.1 mpg since new(9000 miles). I do not tow more than a 4x8 trail or with a lawn mower on it. Can't tell any difference driving from my sons 12 Eco screw 4x4 with 3:55

THe only reason I would do it is if you are going to put a lift with big tires. The locker would be nice (possibly required, depending on the road you are off of), but I think you can do that cheaper aftermarket.

Plus, from what I understand, regearing a 4x4 is not cheap.

Thanks, packplantpath. I guess you've hit the nail on the head. The core question is, "Can I make a decent off-roader (something that can go down some public trails or at campsites) out of my truck without changing its 3.31 axle?" If so, what would I need to do it?

I'm not sure what the answer is. Actually, I'm pretty sure I can Google and come up with a bunch of things, but I want to balance that with the knowledge of some experienced people so I don't do way more than I need to.

If I were doing it... I'd get the complete rear from a salvage yard - with the dash switch. You should already have the pigtail to plug it into somewhere behind the dash. You'll more than likely need the section of wires that goes to the rear end as well. For the front you just need a matching gear set. That's as close to factory as you can get without getting a new truck. If you don't have the pigtail, it's easy enough to hard wire it yourself.

As with any mod, you need to really think about how far you want to go with upgrades so you don't have to buy stuff more than once. If you are wanting larger tires, you need to decide what size first then figure out what gearing will put you closest to your goals.

The Eco makes gobs of low end power so it doesn't 'need' the same gear ratio as say the 5.0 might for the same tire size. However, if you don't gear it properly you will take a mpg hit - how much depends on the type (traffic/hwy) and style (mild/moderate/aggressive) its subjected to.

For reference:
The Eco-Raptor SDHQ built runs 37's with 4.88 gears and gets 16mpg with a tune and exhaust. They would 'probably' get better mpg with 4.56's but they wanted zero lag for obvious reasons.

I had a 2011 regular tow package with 3.31 gearing. The truck was no slouch and towed my almost 5000lb boat with ease. The only thing that bothered me was the open dif allowing wheel slip on less then ideal boat ramps. Putting it in 4low always solved the issues and the truck was able to pluck the boat out of the water with ease. Now on the slipper grass where I keep my boat it allowed too much wheel slip and tight maneuvering was a pain in 4x4. My 2013 has max tow with 3.73 elocker. I haven't had a chance to tow the boat but empty I haven't noticed any loss or improvement in power delivery. However the locking diff will be a bonus in my mind. So far I am using exactly 1L/100Kms more then I was with the 2011, which I write off due to the drag of the tow mirrors and the weight of all te extra options I got on this truck.

Edit: I do notice the truck runs a higher rpm on the 3.73's at highway speeds. Instead of cruising around 1200-1500rpm I run closer to 1500-2000rpm depending on speed.

Ian

Thanks, WarSurfer. I feel like the light bulb over my head is starting to go on.

So if I'm understanding and piecing this all together correctly...

For the type of off-road application I'm looking at, I'm probably fine with my 3.31 axle, as this is associated more with power than anything else. I don't plan to climb rocks or be in any deep mud, so the power I can put down given my engine, transmission and axle is probably OK.

Next, would be ground clearance, traction and protection. If I feel my ground clearance for the type of off-roading I want to do is insufficient, I'll look into a lift kit to raise it up. If I want more traction too, I'd pair that with some bigger specialized off-road tires. And then to protect everything underneath, get skid plates.

Hoping my understanding is good so far...

If I'm on the right track here - and it all depends on what my particular definition/application of 'off-road' is - then it seems like I don't need to worry about the 3.31 axle so much because the power is there. Also, I should look into ground clearance to see if I really need a lift kit and/or new tires and wheels. In any case, skid plates seem like a good idea to help protect everything underneath. This leaves me then with 2 concerns...

1. What about shocks? I'm thinking getting some off-road front shocks might be a good idea in any case. What about rears? Given that I'll be on-road 99% of the time, I wouldn't want anything too rigid or uncomfortable. Any recommendations as to what I should look at?

2. How important is having an electronic-locking rear diff for relatively light off-road use? How difficult/expensive would it be to add one?

Thanks again for your help. I feel like this is all starting to make sense now. Hopefully, I'm on the right track. If I am, it just might be that I don't need to have regrets at all. :D

If you are keeping the 3.31's, I wouldn't go larger than 33's - not because of power but because of the mpg hit. The Eco uses boost to make power, spinning larger tires takes power, power takes gas. I would go up to 3.73's if you think you'll need 35's just to keep the mpg's in check.

Stock replacements from Bilstein / ICON / Fox, etc... You don't need the uber fancy remote reservoir types that are all the rage right now. For the money it isn't worth it, given your statement about mild offroading, unless you just want the look. Fronts and rears, if you want a balanced ride.

A locking diff is very handy in the dirt, I think you can get one for less than 1k plus labor.

Read up on it here:

http://www.fourwheeler.com/techartic...d/viewall.html

Thanks for the great info. I probably won't get around to doing any mods right away. Might be later this year. But when I do, would you mind if I hit you up with questions through a private message? Not too many, I promise.

Thanks again. It is much appreciated.

Don't mind at all.

Thanks again. And BTW, congrats on the Raptor. Looks sweet in your avatar. :thumbsup:

I just got a used Screw 4x4 with 3.31s and I can't compare it to other ratios as I have not any, but I can say WOW.
I have been driving company pickups for the last 7 yrs, first a duramax, then a 6.2, and finally a 5.3. This Eco is well above 5.3, and I would rank it closer to the duramax than the 6.2. I drove the 5.3 truck to get it and loaded that on a trailer behind the Eco to come home. I believe mileage according to the dash was under 8, but the truck dindnt even know that "rock" was behind us.
I am hoping either the dash mileage is off, or it improves with miles, empty cruising at 80 was about 14.
I test drove the 5.0 and 3.55 ratio boost before buying this one and empty I noticed no difference in any of them.

2013 eb screw 3:31
 

I just picked up a used (19000 mi) 2013 eco 4x4 screw 6.5' box and 3:31 gears. I really wanted the 5.5' box and 3:55 gears, but got a steal on this one that I couldn't afford to pass it up! It came with A.R.E brand Tonneau cover, spray in bed liner, Banks programmer, weather tech floor mats, AFE intake and heart throb exhaust! I will pull a 5000lb camper several times a year and hope it does well. Around town I'm seeing 18-20 if I keep my foot out of it. Anyone have exhaust or intake perhaps programmer? If so what's your experience?

I don't have exhaust or intake but I'm tuned. I have the SCT x 4 device with three 5 star tunes 87p/t, 91 p/t, 91p, I usually switch back and forth between the two 91 octane tunes and they are freaking awesome. 2nd gear scratch, pull hard, great power and Trans shifting.
My truck is a 2013 xlt 4x4 S.crew cab EcoBoost 3.31 gears with some suspension upgrades/mods
After the tune I won't be doing much more performance wise, it's perfect.

I've seen great stuff about the SCT but don't have any experience with it. Might sell the Banks and try the SCT though.

It pretty much seems to be the go to with the ecoboost, also multiple tuners write tunes for it so there's a good selection of custom tunes to chose from.

Lol ya I'm gonna look into it for sure. I really like it has gauges.

You'll do fine. I pull twice that weight with 3.55. Approaching 10,000 pounds I get 9ish mpg.

I have 3.31 and while I wouldn't say I have regrets. However, I would LOVE some 4.10's. So far I haven't seen too much power issues and my MPG is great (20+ highway). I also haven't done extreme towing.

I traded in a 2012 xcab 5.0 with 3:55 (drove for 2 years with 33,000 miles) for a 2014 xcab eco with 3:31. Both trucks were 5 star tuned with 87 p/t. The tires lose traction with the eco so much easier than the 5.0. The 3:31 on the eco has plenty of power and average 17.8 mpg with a heavy foot. On the highway at 70 mph average 23-24 mpg. That is my 2 cents.

My 2011 2wd had 3.55s but I did not tow with that truck...ran great and pretty good mpg.


My 2012 4wd has 3.73s with 2" lift and 34.25" tires and I tow a 29" TT...no problems.


With the low 1st gear and 6 speed trannies...I would think that even the 3.31 on stock diameter tires would be just fine.

I have a 2014 XLT with 3.31 gears.
My Dad has a 2014 FX4 with 3.73 gears.

I consistantly get above 20 mpgs and my dad can't get higher than love 17s. Both of us use our trucks to mainly commute with maybe a little towing / hauling on the weekends. Next time around I'll get getting the lower gears as well for sure.

Not too bad with mine towing up to 5K pounds...anything heavier I'd want the 3.55 or 3.73's. I went up one inch in tire height so that doesn't help either. Still get up to 20 mpg hwy at posted limits so that's not bad for a fairly heavy truck. Using the tow haul or manual mode can give you a gear for every occasion with the 6 speed tranny!

Nope no regrets with my Lariat. I do wish I had a locker but I get decent fuel mileage with way more than enough power. To be honest the only differance if you want it in eay terms is the truck with 3:73 gears is only getting a 1/4 more turn of the drive shaft as opposed to the teuck with 3:31.

I have 3.31's and a tuned Ecoboost. I love it although I could feel a slight performance hit and a definite mileage hit when I went to 285/65/18 BFG KO2 tires. They are Load E, so I think that is most of it. I have also moved to Pittsburgh, from relatively flat Georgia and most of my driving is now city as opposed to highway. I was getting 18-19 in Georgia. I am now at about 10-11 in Pittsburgh. Of course some of that, is probably my right foot with the tune. Hahaha.

All of that to say, I don't regret it per say, but I would have looked more at gear ratios when buying the truck if I knew more. This is my first ever truck. I do hope to ultimately put Raptor size tires on my truck and when I do that, I fear I will need 4.10 gears.

Nope, no regrets for my Highway Queen!

I have a 2012 with 3.31s. I have 35x17r17 tires and a level. I tow a 27 foot camp trailer with two slide outs. It does fine, plenty of power. I live in eastern Idaho, so that means lots of hills to climb. I have no regrets.

Nice! I'm planning on getting some 285 /75 /17 bfg mt km2 's
Kinda worried due to my 3.31 gears. That's good to hear.
I assume you ment 35/70 /17's ya?

Nah miss print 35x12.5r17. Toyo at2 on raptor wheels.