MJinMN

Hi all, have been reading the forums the last few weeks and have learned a ton, thank you. I'm trying to decide what to buy/ order, between all the different engines and rear combinations. I am not a heavy tower, looking for a daily driver that I can occasionally tow a boat or small trailer and take hunting in nasty spots, but nothing that should challenge either the EB or the 5.0. With that in mind, obviously greater towing capacity means more flexibility, but probably worse mileage. Does anyone have a guess as to how much MPG I give up going to the 3.55 or the 3.73?

canuck8

Glad you asked that question. I too have been lurking about reading all of the excellent information available on the site. I have been putting off on purchasing a new F150 as the debate went from buy a 2010 while I still could (tried and true motor) to which motor in the 2011. After driving both the 5.0 and the 3.5 the answer became quite clear. The 3.5 was definitely the one for me. When I went to build a new EB Screw 4x4 online (canada) I found that you can't get the 3.73 without going to the max tow package or off-road package.........as I want neither (my towing needs max out at about 5000lbs) I was disappointed. Could it be that the diesel like torque curve doesn't require the higher gearing 3.73+ for decent towing? You can get a 5.0 in 3.73 without an offroad/max tow package which tells me this gearing is needed for a decent tow. I will admit that the terrain here in BC will be hilly but I really don't want the beefier packages.........will the 3.55 in the EB be up to the task?

varithms

3.55 vs 3.73 might be 250-300 rpm difference at cruising speed given all other factors are the same.

3.55 and lower are good for lots of hwy driving for better mpg
3.73 and higher yield better mpg in city driving.

Msuforeman

I have a 2011 XLT Screw 5.0 5.5' 4x4 3.73 with 750 miles. I drove it 150 miles today at 75 and it showed 17.5 on screen. I then hooked up to a 6x14' single axle trailer and drove another 150 miles at 75---after resetting economy it showed 13.9 on screen.

Chicane

And the associated math for the emperical...

As long as the tire and wheel package remains the same, for example... the stock 275/55/20 on the FX4 is 31.9" dia...

3.55's in sixth gear @ 70.00972mph = 1807 engine rpm

3.73's in sixth gear @ 70.00743mph = 1980 engine rpm

A difference of 173 engine rpm.


And for those going with the 4.10's...

4.10's is sixth gear @ 70.01114mph = 2087 engine rpm