Hi Folks,
I need some input as I am really confused. I own a 2008 f150 4X4 XLT, auto with 3:55 rearend gears, 7400lbs GVW tow rating. I tow a 5700lb GVW travel trailer(not nearly loaded).
On the flat it tows well, but traveling over the mountains, has a hard time. One stretch is 5500feet altitude, with a fairly steep grade for about 3 miles or so. On this stretch of highway I will have the truck floored and only get up to 40 - 45mph at a maximum of 3000rpm. The overdrive is off. It seems to be in second gear, but this seems more like drive.
Guess I could understand the speed but the 3000rpm tops confuses me. The dealer says it is the rpm rev limiter working. If so why does the truck rev way past that on the flat and on lesser grades? Is it just tapped out?

 

The 3.55 gear ratio has a hand in it, plus it isn't a diesel.

 

It's not the rev limiter - you are in fact in 2nd gear and it's pulling as well as it's going to pull. Yep - it's just tapped out. To get significantly better performance under those conditions, you need a diesel.

 

3.73 would help a little... Also, what speed to you hit the grade at. I find accelerating up a grade is different from holding a speed up a grade. Is it interstate - If so, can you start the grade at like 70-75?

 

Gas engine, 5700 pound pull and mountains don't exactly go great together. If you pull threw the mountains a lot, I suggest forking up some cash on a diesel.

 

Thanks for replies.
Yeah I've been thinking about a diesel, but just hate to go into debt for one, as I only take this particular route a few times a year, and the truck is satisfactory in every other way. Also thought about gear change to 3:73 or a blower. Put on a CAI and spacer that may help. Haven't tried them towing yet.
Not looking for a racing machine, just would like a little more pulling power, 5-10mph.
The dealer suggested a programer. Don't know which one to try as they all sound good. I would like to keep 87 octane. The dealer said buy an Edge.

 

^ Okay...

If your going to change gears, you had better go lower than 3:73 or you won't notice much of a difference and you will have wasted a lot cash. Go 4:30.

Blower? Big price tag for the blower alone. Now you have to build up your tranny. The stock tranny will not hold up to boost and hard pulls up the mountains.

CAI will not make any difference at all for you pulling, and a spacer is a waste of money on a fuel injected engine.

Diesels are the only way you will be happy pulling that load threw the mountains.

 

get a gryphon and a custom tune for towing...gears and maybe cams

 

If you only take this route a few times a year, I wouldn't worry about it. Not worth the expense for only a few passes a year. Creep through at 45 and keep thinking about all the money you saved.

 

Just curious, what size tires are you running?

 

Cams will hurt your torque curve and make towing worse.

 

depends on the grind if you pick a grind that makes an *** ton of torque at 2000 to 2500 ud be set

 

4.10's at a minimum if you are going to do a gear swap.