Gas mileage comparison

[portalto]

I currently tow a 23' 2007 Safari with a 2007 Ford F150 Super Crew with the small 4.6 V8. I have an equalizer sway weight distribution set up. My question iswhen towing which would get better gas mileage(only changing the engine)the 5.4 V8, the 4.6 V8 or the new V-6 double turbo Ford is putting out. I really only use the truck to tow so I don't care about the regular mileages that they advertise. Thanks for the help.

[jcanavera]

While I can't comment on the Ford products, here's my experience with my GM vans. Van 1 was a half ton 5.7 liter 3.73 axle pulling a 6,000 lb. 27 ft Safari. Had to tow in 3rd gear no OD per owners manual. 10-13 mpg towing.

Van 2 was a 3/4 ton 6 liter 4.10 axle pulling an 8,200 lbs 30' Classic. Can tow in OD per owners manual. 10-13 mpg towing.

Where the real difference is when I'm not towing. Van 1 was about 17-18 mpg with Van 2 around 13 mpg.

Jack

[xonvldz]

my experience tells me speed is the killer on fuel mileage .55mph and keeping your engine rpms within the power range should produce the best results,

[barts]

Hmmm... if you tow on the flats, you're best off w/ a rig that lets you run in OD while towing... it actually doesn't take that much power to pull our trailers on the flat. At 55 mph, w/ diesel (only for example), if you get 15 mpg you're actually using about 36 hp (assuming 10 hp-hr/gal).

Now, gas engines perform most efficiently loaded at the lowest speed that will produce the needed power, since running at higher speeds requires throttling the engine and increases pumping losses. Diesels also are more efficient at lower speeds, but this effect is much less pronounced there.

So, all else being equal, get an engine/tranny that lets you tow in OD. Now, if you do a lot of hill climbing, you're going to want enough power to pull at a reasonable speed up the grades. This is a much more complicated problem, since this involves power curve of engine, gear ratios available in tranny and amount of weight you're dragging up the hill.
The difference between second and third gear is usually quite large, and mileage drops a lot if you have to climb in second.... There's a reason the new heavy duty Ford has a six speed automatic - you get to match the optimum engine speed w/ the load w/ fewer compromises.

[gmwelder86]

The 5.4 seems to be torque monster, its power band seems to be really low in the rpm range which is great for towing.

All mileage while towing is going to be bad, it doesn't matter who you talk to everyone seems to be getting from 9-13mpg pretty much regardless of engine and manufacturer differences. I think a solid motor and a 6 speed tranny and if all you use the truck for towing up the rear end ratio that would allow you to use the 5th and 6th gears. And I am saying 4.10's and higher. 3.73's are good but 4.10s would be better for a straight TV

[portalto]

Thanks for the advice. Seems the rear end ratios and transmission speeds mean more than horsepower. A glaring generalization I know. My current truck has the 4 speed automatic. The new f150s have a six speed transmission. That could be a total difference. I always tow in od on the flats. Can't see much difference even on the hills. That might be the 4 speeds. 6 speeds could make non overdrive really work better in the mountains.

[boondockdad]

2500 Suburban 8.1L. 1400/14000 Hensley. 30' S/O. 7-8 mpg (65 mph). Unhitched 11-12 mpg.

[gmwelder86]

The nice thing about the 6 speed is you usually get 2 overdrives, or atleast thats how my tundra is 4th is 1:1 5th .728 and 6th .558. This way you wont end up with a huge rpm jump when going from OD to 4th as I am sure you have expereinced.

[brad1]

Just got back from a 684 mile trip with moderate mountain climbing. Towed our fully loaded 19' International with F150 5.4L and got 16.8mpg actual.

[portalto]

That is great. What year truck? Does it have extras and ups or just the regular package. How about the transmission and rear end? Thanks for the info.

[eddiejenn]

I went to tenn to pick up my 1976 31' AS and I was getting 14-16 mpg. With a duramax 4x4. But there is no comparison if you want good towing and good gas mileage go with a dodge diesel. I could haul my 20 ft flat bed with a backhoe and was getting 18mpg. It got 22 empty. I love how this chevy rides, but if you want power, performance, easy to work on and great gas mileage pay the extra money and get a dodge diesel.