Ideal V8 rpms when towing?

[Siletzspey]

My F350 SRW 4x4 with 6.2L gas has a 3.73 axle and 18" tires. I carry a 9'6" NL truck camper which puts me at about 11,000lbs total.

When cruising at 70mph, I turn 1,800rpms in 6th gear, and 2,300rpms in 5th gear. On a mild up slope the engine seems fine in 6th at 1,800rpms (e.g. I don't get any odd sound or sensation of lugging).

Is there any thought on what a good rpm is for the engine and transmission when towing a load? With my prior 1997 Ford Expedition, the TOW button would disable the highest gear (OD).

I also plan to upgrade to a slightly larger 18" tire so I can go from 3,640 to 4,080lbs per tire, and estimate 6th gear will drop to 1,700rpms, and 5th to 2,200rpms. I wonder if I will want to purposely avoid 6th?

Thanks,

--SiletzSpey

[Siletzspey]

Thanks for the replies!

I realized after asking that there is a miles-per-gallon optimization aspect, and a wear-and-tear optimization aspect, and I was thinking more of the latter.

I guess I've gravitated towards the answers that suggest the transmission and computer will choose a reasonable gear for all concerns. I do use the UP and DOWN arrows to set what top gear is allowed when 5-6 jumping occurs, and when going downhill.

Thanks,

--SiletzSpey

[theoldwizard1]

Siletzspey wrote:

When cruising at 70mph, I turn 1,800rpms in 6th gear, and 2,300rpms in 5th gear. On a mild up slope the engine seems fine in 6th at 1,800rpms (e.g. I don't get any odd sound or sensation of lugging).

Is there any thought on what a good rpm is for the engine and transmission when towing a load? With my prior 1997 Ford Expedition, the TOW button would disable the highest gear (OD).

My old E150 was the same way. I would frequently disable OD when approaching a hill so that it would not lug down too low before it kicked down itself.

The newer Ford 6 and 10 speed transmissions are computer controlled and the engine should not lug down too low. I am sure there is a way to manually shift it. If you manually put it in 5th, it is going to stay there forever, even when you slow to a stop, unless you shift it or put it back in full automatic.

[Kayteg1]

When new computer programs adjust the gears torque-wise, they lack intelligence to plan for engine cooling on long grades.
It was common on older heavy sets that well pulling engine will overheat 1/2 the way up the mountain and easy prevention was force it to drop couple of gears when starting and not going faster than 1/2 throttle.
This way higher rpm with less load provide for better engine cooling.
Same going downhill, when even with engine brake and speed controlling program, you might face situation that will call for more downshifting.

[valhalla360]

specta wrote:
Transmission selector in D, tow haul button engaged.

Let the truck decide what's best. 😄

Yep, with modern trucks, the engineers have sorted out which gear the transmission wants.

Now if you have an older truck or manual transmission, it's valid question.

[specta]

deltabravo wrote:

Kayteg1 wrote:
Each engine has it "sweat spot"

My Duramax doesn't sweat

😄 😄 😄 😄

Neither does my 6.0. 😉

[specta]

Transmission selector in D, tow haul button engaged.

Let the truck decide what's best. 😄

[Bert_Ackerman]

time2roll wrote:
I usually recommend close to the rpm associated with the peak torque rating.
Maybe a little lower if lightly loaded and a little more if running heavy.

Op is talking about cruising and slight grades, depending on the year of the 6.2 you usually recommend doing that at 3800 or 4500?

[deltabravo]

Kayteg1 wrote:
Each engine has it "sweat spot"

My Duramax doesn't sweat

[MORSNOW]

It's RPM (Revolutions per minute)as in the number of turns in one minute. Not RPMS (Revolutions per minutes), we have no idea how many minutes you are talking about.

Lower RPM does not always give the best gas/fuel mileage, you can lug an engine down too low and hurt your mileage. Depending on your load, the sweet spot can change for the best mileage.

[jaycocreek]

Keeping the mighty 460 to 2,000 rpms,makes it sip gas....Luckily,most of the roads I travel have 45-60 mph speed limits...4.10 gears has it zipping up the hills like there not even there..Faster than a speeding bullet and more powerful than a locomotive ...

The 460 Ford(Laughing)

[bwlyon]

We have a Ram 3500 SRW 6.4 hemi with 3.73 gears. As a general rule the hemi likes to cruise at 2000-2500 rpm. Depending on speed limit posted that means either 4th or 5th gear on our 6 speed auto transmission. If we are cruising in hilly terrain 4th gear seems to be the best gear to limit down shifts.

[ajriding]

Consider your transmission also. Is 6th gear an over-drive gear? If so, then it may be putting a lot of heat into the tranny with such a load, uphill in overdrive. I would never do this without a transmission temp sensor.
Automatic will figure it out for itself, but a manual will not. Shift down on almost all hills.

[NRALIFR]

I think mine is at the right rpm when it goes “bubbita bubbita bubbita bubbita bubbita..........”.

Just like that. Puts the boss to sleep. :W

:):)

[Bob_Shaw]

Torque, rpms, sweet spot... it all sounds great, right? Try this try towing your trailer over the same route at different speeds, and see how much your fuel mileage changes at the different speeds. Then pick the speed/fuel mileage you can live with. You'll be surprised how fast your fuel mileage drops the faster you go. When I was working, I was in a hurry, and towed at 75 mph and used to get 4.5 - 5.5 mpg. After I retired, I tried slowing down to 62-65 mpg and my fuel mileage climbed to 8.5 - 10 mpg. I guess I'm not in that much of a hurry any more.