I have to believe the Yukon weighs less than the F-150, and the tow mirrors don't help with wind resistance either. I tow over 8000 lbs. and get between 8-9 mpg, and if I tow above 70 mph. its less. I too have the Eco with 3:73's with a 6.5' bed, and that comes at a fuel economy penalty. My old 2010 FX4 with the 5.4 V8 towed my trailer with little power reserve and at around the 7 mpg range, so the ECO or BOOST engine isn't that bad of a trade off.

 

It was a like a contractors trailer that I borrowed from my neighbor last summer to help another friend move to a neighboring city about 25 miles away. I had to make two trips with this set up. The trailer is a tandem axle and the roof line is higher than my truck.

I get what you're saying, I should have been more clear. But, the fact remains and we've agreed on this in the past, the 3.31 axles are plenty behind the ecoboost for lighter work and daily driving.

 

Absolutely.

 

We are probably talking different things here. I am referring to general principle of physics of the motor to produce power, comparing each other. You are correct at where ecoboost produces power relative to the NA engines including the 5.0. much lower But to make power at 1.5 liters smaller than 5.0 or 1.8 smaller than Chevy 5.3, it uses boost to add more air and fuel. Given the 10:1 compression the boost actually makes the compression higher than the 5.0 10.5:1 ratio to produce the basic power needed. Without boost, the rpm would need to be higher to make up the basic displacement loss. But I see your thinking of less rpm, less fuel, its just not the case if trying to produce power vs riding along at 70 at light throttle.
All things are never equal- displacement size, compression ratio, cam timing and then throw in boost and everything is out the window. But the same theory applies in producing any power, fuel and air, its just how much...
And a new set up is only better than the old engines in improving intake and resulting output. Adjusting intake runners, timing, boost, that's the trick to fuel economy year to year. You are right, I was just off in another field...
General outline...
Producing More Engine Power - HowStuffWorks

 

I agree with this. For my uses, it's a GREAT trade-off.

 

I'm tracking. All I was saying is that the EB is peaking for torque around 2000-2500 RPM, so it can sit there and pull at that RPM vs. the NA engines that need to downshift to get back in their torque peak of 4000. The EB will just add fuel & build boost to maintain speed up a hill instead of downshifting. That's what I meant by "all other things equal"...

Check out the Ike Gautlet runs with the EcoBoost on YouTube. Pretty impressive.

 

Bakon, whew, when yall boys go to digging that deep in physics mumbo jumbo, I'm outta here. Me old haid cain't take it. I'm with old Red of Red/Green show. He speaks me language.