Has anyone towed close to 10,000 lb's in the rocky mountain states with a 5.4 / 6spd.? If so how'd it pull on the interstate with 6% grades?

 

I bet that will not be a fun experience.

 

This is a very vague question IMO. There are several factors that apply to towing over the max weight. The 5.4 6spd has a max towing of 9600 LBS. What axle ratio? With or without max tow package? What kind of trailer? Stock suspension or do you have a lift with larger tires? I'm sure there's many more.

 

Wow, I'd much rather be in a Superduty with that much weight and steep hills. Sorry I couldn't help more, but in my 2003 5.4L (2wd & 3:55's) with a 7,000lb toy hauler. I had a decent hill (5 miles long, 3%) and I had the throttle mashed the whole time. We pulled it 50-55mph and about 5,000rpms the whole time. I was under warranty and figured she's gonna break or we'll make decent time over the pass. The same trailer with my 08 SD 6.4L diesel just for kicks I did the same thing, but pulled it 75+mph and no groans or drivetrain noises screaming. I laid off the throttle just because towing at that speed just isn't smart. I lowered it to 65mph with plenty of throttle left.

 

What kind of trailer?

 

I'm looking to buy a Sandstorm 263 which is 6700 lb's dry.

 

That's going to be over limits and very painful. On 6% grades over 8000 feet, you will probably be down to 20 mph in 1st gear in the slow lane. At that altitude at that load, that's forced induction territory - preferably a diesel.

 

^ yeah, I didn't even think about altitude. 10k & 8,000ft will kill any nat aspirated motor.

 

Depending on tires, tow package, and rear end ratio, the 5.4 with 6 speed is rated for up to 11,300 lb.

 

6700 lb. will probably weigh no more than 10k, which is well within limits.

Steep grades at high altitude will probably slow the rig dramatically but, if pulling only occasionally, that is better than having to pay for reduced gas mileage the rest of the time.

 

I have done the Rockies multiple times in F250 diesel 4wd crew cabs. It was the minimum I would take through the mountains at that weight 32ft and 10k lbs. Ford says to de-rate capacity for altitude and conditions in the manual. I had my Super Duty in tow haul coming down Cottonwood Pass, Raton Pass, Monarch Pass etc. There were a few times the tow haul was holding 4k rpm which is a lot for a diesel all the way down the grade which was 4-8 miles some times. I was holding my breath hoping the diesel could engine break and hold the speeds low enough to make the curves without smoking the brakes.

I did tow my lighter Keystone 245RB at 6k lbs to Lake City, Pikes Peak and Taylor Park, CO. My 2010 FX4 F150 screw handled everything safely and within my comfort limits. I had to go 10-15mph slower than I could at altitude due to the lack of HP but I still got there.
Of course there are people that tow crazy stuff but I am a bit more conservative. I'd say 26ft and 6k lbs is the most I would tow through the Rockies with a F150. The truck doesn't have the compression braking to hold down speeds down long grades. You would smoke the brakes going 5-10 miles down a grade without good engine braking.

 

Ive done it plenty of time with my '05 F150, is it fun no, but its the only thing I had so it worked, run as hard as you want just watch those tranny temps. And watch your breaking, just go as fast as your comfortable with.

 

On an interstate with a 6% grade how much would your speed drop down?

 

I Googled the trailer and it looks like a high profile toybox. That has to factor in to towabiity. Wind profile is a buggar and throwing a couple ATV's in the back could change the balance a bit.

 

^ Heck yeah. My trailer was a 21ft Gearbox (not ultra light). With the F-150 the tail would wag the dog. I would also drain all the fresh water and dump any left over food or wood just to lighten the load after camping. With the F-250 everything would come back home and I'd even keep the left over fresh water in the tank so I could water my plants when I ghot home. Also, the tail wouldn't budge that dog. Even huge wind gust wouldn't faze the SD while towing.