3.55 or 3.73 with ecoboost
11-14-2011, 08:07 PM
#53
Senior Member
My 5.0 with 3.73....This is what I usually get. But for some reason this tank I have now i'm getting 19.0. That is probably 70% highway driving. Oops sorry this is an ecoboost thread. But I am just showing that a 3.73 can get good mpg too.
11-14-2011, 08:44 PM
#54
Senior Member
Nice mileage with a 5.0 and 3.73's
07-21-2013, 11:14 AM
#55
It is always an interesting discussion when rear axle ratios are discussed. I think one fact that gets largely overlooked is that we are no longer in the age of three or four speed transmissions with large steps between each gear.
Rear axle ratios matter much, much less these days with modern six or more speed transmissions that provide a gear much better suited to the particular speed you want to go with your trailer and also provide the torque amplification you need to get going or to hold a certain speed on inclines. Sometimes a lower numerical ratio (i.e. a 3.31) is actually better because you can tow at highway speeds and the "right" rpm in fifth gear better than with a higher numerical ratio (3.73) in sixth gear.
My point simply is. There is literally not nearly as much difference between all these ratios with the six speed in our trucks vs. in the old days when you only had three or four ratios and needed the rear axle to be geared for optimal pulling in top gear.
As far as driving without a load. Having compared the 3.73 and 3.31 extensively before buying my truck the 3.31 seems much better matching the ecoboost characteristics than the 3.73 when driving without a load or trailer.
If I had to tow all the time I might consider the 3.73 gears. They do boost your legal max. trailer weight to 11,200 from 9,200 for the 3.31 (even though if I had to pull those kinds of weights I'd get a SuperDuty Diesel!). If I only tow occasionally (like I do ... less than 2% of my total mileage) I absolutely would get the 3.31 gears again. The 3.55 gears are in real life no different than the 3.31 (Top gear RPM are only 100 rpm different between the two and max. trailer weight is 9200 vs. 9600 lbs..) so take your pick.
Unrelated to this thread ... what surprised me is that the 5.0 in my configuration (SuperCrew/145") with 3.55 gears can only tow 7,700 lbs. and only 9,300 with the 3.73 gears while the SC/145" w/ecoboost can tow up to 11,200 lbs. with 3.73s or 4.10s
Rear axle ratios matter much, much less these days with modern six or more speed transmissions that provide a gear much better suited to the particular speed you want to go with your trailer and also provide the torque amplification you need to get going or to hold a certain speed on inclines. Sometimes a lower numerical ratio (i.e. a 3.31) is actually better because you can tow at highway speeds and the "right" rpm in fifth gear better than with a higher numerical ratio (3.73) in sixth gear.
My point simply is. There is literally not nearly as much difference between all these ratios with the six speed in our trucks vs. in the old days when you only had three or four ratios and needed the rear axle to be geared for optimal pulling in top gear.
As far as driving without a load. Having compared the 3.73 and 3.31 extensively before buying my truck the 3.31 seems much better matching the ecoboost characteristics than the 3.73 when driving without a load or trailer.
If I had to tow all the time I might consider the 3.73 gears. They do boost your legal max. trailer weight to 11,200 from 9,200 for the 3.31 (even though if I had to pull those kinds of weights I'd get a SuperDuty Diesel!). If I only tow occasionally (like I do ... less than 2% of my total mileage) I absolutely would get the 3.31 gears again. The 3.55 gears are in real life no different than the 3.31 (Top gear RPM are only 100 rpm different between the two and max. trailer weight is 9200 vs. 9600 lbs..) so take your pick.
Unrelated to this thread ... what surprised me is that the 5.0 in my configuration (SuperCrew/145") with 3.55 gears can only tow 7,700 lbs. and only 9,300 with the 3.73 gears while the SC/145" w/ecoboost can tow up to 11,200 lbs. with 3.73s or 4.10s
Last edited by Alex D; 07-21-2013 at 11:26 AM.
07-21-2013, 01:37 PM
#56
I have proof what mine does...where is your's on a 3.55's EBOOST getting 2-3 mpg better than 3.73. Laughable...and nonsense. There are dozens of 3.73 owners reporting 20 mpg on this site....and more that know there is little difference between the two gear choices . Just doing your math would mean a less than 5% reduction in gear equates to a 15-20% increase in fuel mileage....nonsense. We should all get the 3.31's, a 12% reduction and reap 50-60% better mileage. Those two wheel 3.15's ought to be getting 30 mpg with your math.
As for my opinion... based on a lot of reading on several sites. The 4X4's EBOOST trucks average about 19.5 -20 with 3.73's. The 3.55's are in the 20.0 to 20.5 and the 3.31's which are hard to find and see reports on are another .5mpg. Mine does a little better than the average due to the intake and exhaust. I also see 95% highway use on pretty flat roads.
07-22-2013, 09:41 AM
#57
Nathan
On two recent highway trips (to and from the mountains), my gas mileage was a solid 21mpg at 70mph. (i.e. dash gauge said 11.2 liters per 100 kilometers) The total distance to achieve this was 785 miles, with about 20 traffic lights total.
If I consider the weight I'm hauling—and the speed I was travelling—I think this is amazing!
07-22-2013, 10:01 AM
#58
I have 3:15 on my 13 Eco screw 4x2 lariat. Just got back from 350 mile road trip. All two lane hwy with many stops. 4 people and back loaded with luggage with undercover bed cover. 22.6 mpg. Cannot tell difference on power from my sons Eco screw with 3:55 gear
07-22-2013, 11:06 AM
#59
If you are towing heavier loads and live in an area will hills, the lower the gears the happier you'll be in the long run. I have an Econoost SCrew with a lift and 35" tires so when I ordered my truck from Ford I went with an FX4 package and the 4:10 gears (about 3.7s with the 35's if you do the math). Where I'm pulling about 7500lbs in the state of WA I would not recommend going with any higher gears (3.73s are great, but if your doing a lift and 35's, go with the 4:10s which comes out about the same). However, if you live in a state that has less hills and mountain passes than WA and if your hauling lighter loads, without taller him tires then you would probably be OK with 3:55s. But if you are pulling heavy, live where there are mountain passes and hills, and you want to be able to maintain the speed limit, then you should really consider 3.73s or lower.
So - where do you live, what will you tow, do you want to be able to maintain the speed limit over passes and hills, how much payload will you adding in addition to what you are towing, and in the future do you see your yourself buying a larger toy to tow, etc etc. This should help you narrow it down and others probably have additional suggestions. Oh, and definitely buy the max tow package. Good luck....
So - where do you live, what will you tow, do you want to be able to maintain the speed limit over passes and hills, how much payload will you adding in addition to what you are towing, and in the future do you see your yourself buying a larger toy to tow, etc etc. This should help you narrow it down and others probably have additional suggestions. Oh, and definitely buy the max tow package. Good luck....
07-22-2013, 11:11 AM
#60
If your not towing heavy loads and want the gas mileage then higher gears are the way to go - wow, 22mpg is fantastic. With my 4:10s and 35" tires I've never gotten over 18.5 (not towing). With towing 7500lbs+ with hills I get about 12mpg on average.
