Ok gents,

I've posted this info dozens of times and it seems to keep popping up. Gas mileage with the various gears. New users are coming here and looking for info on which gear is best. The only advise we can offer is to drive the truck and describe it's anticipated use.

OK, these are real numbers from today. 2011 F-150 Ecoboost 4x4 Scab 3.31 axles.

We took Sarah back to school today, a 400 mile round trip from the coast and flat lands of Virginia to the Virginia mountains and back.

Going, I was well loaded and headed North West with a steady climb for the last 60 miles and I averaged 21 MPG's doing 70-80. At 80 mph, I tach 2000 RPM's. She never downshifted once.

Coming home and headed South East and descending from the mountains, driving 75-80 I averaged just over 23.

There's no fricken way that I can hold this stallion to 60-65.

This posting is meant for information only, comments are welcome of course. Oh, and the truck is still rated to pull around 9K. That's plenty of truck for the majority of us.

So, for those on the edge and can't decide but MPG's are paramount.......

 

As a future buyer, thanks tsee! That is indeed helpful information from someone who actually has that differential. Wow! With 4x4 too! To me, this kind of really shows what Ecoboost is for - 3.31 gears, and can still tow that much! I don't think there is another gasoline engine that can match it.

 

I also have a 4WD Screw EB with 3:31 gears.
Over 22,000 miles, my overall milage is an honest 20 mpg. My driving is very consistent, and I can say winter fuel knocks it down to the 19 range. Summers are 21. I live at 6000 ft, and all my driving involves highways and mountains.

Recently I drove several hundred highway miles at night, only going 55 (1300 rpm) (deer are the smallest critters I worry about on these roads).
After filling up, I started at 4000 ft, went up to 7K, down to 6K, back to 7K and down to
4K. Then did it all backwards. Truck got 23+ mpg in these mountains for 200 miles. Unbelievable.

Driving 80 (2000rpm), which is legal in some parts of my state, and 75 the rest of a 1400 trip last winter, I got 18 on those legs.

I test drove EB's with 3:55s and 3:73s, and in conservative driving on our mountain roads, didn't see a whole lot of difference in performance between them. In fact the overall performance was so incredible going up these mountain grades at 7000 ft, I ordered mine with the standard gearing.

Also tried out the V8s. Both very nice; would have been happy with either one, but at this altitude, the performance gap between them and the EB is very noticeable.
My 2$ (better then 2 cents)

 

I average anywhere from 16-18 city and 19-22 highway. Recently driving the 72 mile roundtrip (85% highway) to work and back for the last 4 days as well as the regular stop, go, idle, while at work I averaged 21.5 for that tank of fuel.

2012 Supercrew 5.0, with 3.31 gears and 26,400 miles on the clock.

 

Gear ratio math is now more or less a dead horse.

Here's why: Back in "the old days," automatic transmissions had a first gear ratio of 2.5 (or so) to one. When you tried to get the truck moving, even with torque-converter slip, you made the engine fall on it's face trying to get the beast moving with such a numerically low gear ratio. Thus, enter the numerically high gear ratio rear-end. Of course, then you had the engine screaming it's guts out at freeway speeds. Enter the overdrive gear on a 3-speed transmission (with the aforementioned 2.5:1 first gear). Now you had a way of keeping highway RPM's low, but have decent pulling power to get you (and your load) off the line.

Nowadays, transmissions have at least one more gear (6 and 8 speeds), and a much deeper first gear ratio. A truck no longer NEEDS a 3.73 or higher rear-end gear, on factory 29-inch tires, to both get up and go, and still get decent mileage. Today's automatic has a deeper first gear than almost any manual-shift transmission ever offered in a pickup-truck, combined with 2:1 converter slip. '

What used to be absurd (a 3.08 in a truck?!? Bwahahaha!!) is now commonplace because the technology in front of it is much better.

-blaine

 

^^^^^^^

Kinda funny that this comes up. Back in the day long before I bought my truck, I was shopping for a superduty. I just thought I had to have a smoker.

My shopping and research reveal a puzzling piece of information for me, the trucks with 3.31's had the same tow rating as trucks with the 3.55's. I kept thinking, how is this possible?

All I could remember was how doggy my '84 and '86 trucks were with the 3.08's, I passed on those superduty truck and it's best.

Being on FTE has taught me a thing or two about putting the power to the ground and how the six speed was a game changer in these trucks.

My truck sat on the lot for six months, it's not well enough equipped or the 3.31's scared everyone off or both. Either way, I got a screaming hot deal on a great truck!

 

The 3.08s are still offered, and the extra trans gears do help, but they are not a magic fix... Watch the video of the Chevy in a recent thread on this forum... Even though it has a gutless turd of a 5.3 (Aren't all Chevy motors torqueless???) the truck was really straining up the hill they were pulling. The main excuse made by the hosts was that the 3.08 rear gears (in a Z71 no less!) were just too high for any sort of heavy towing (well, any towing with a Chevy is not going to be a fun experience...).
For light hauling and towing, 3.08s are ok, given modern transmissions, whereas the same loads could never have been adequately handled by older 3 or 4 speeds. However, if one really is doing some towing, especially in hilly terrain, lower gears are still a must.