Tow vehicle fuel question

[switz]

If the OP does a lot of mountain driving, another option would be to retrofit a small turbocharger on the gas engine. One would not be looking for lots of boost but the ability to maintain sea level power to say 10,000 feet which would cover most of the roads in North America.

[Jack46]

Thanks again for all the replies. Very helpful.

[dkottum]

By the way, I always select a gear to keep the engine above 2000 rpm when pulling the Airstream even on level, for us that is 4th (of 6). That keeps the transmission from down shifting on the usual rises in grade or strong headwind. I don't see that increasing fuel use at all because the engine pulls comfortably there and the transmission does not hunt.

[FastEddieB]

As a data point, my 2011 Flex with EcoBoost says this:

3.5L V6 EcoBoost engine

Your vehicle is designed to run on regular fuel with an octane rating of 87 or higher. For best overall performance, premium fuel with an octane rating of 91 or higher is recommended. The performance gained by using premium fuel will be most noticeable in hot weather or in severe duty applications such as towing a trailer.

So far, I've just run regular, to no apparent ill effect.

[Jack46]

I did order the Suburban with a 4.10 rear end. At the time I thought I would need the extra towing capacity, but we ended up buying a 7,300 gw AS rather than a significantly heavier brand X.

Regarding mileage, we get about 10 mph hauling and about 19 mph on open road without the trailer. Living on the east coast we expect to travel west only intermittently. But the mileage highlight (or lowlight) of our trip last summer was the 4 mph we experienced climbing the sixteen miles between Oray and Durango, CO. Ouch!

Thanks again for all the replies.

[Jack46]

Oh, and we found ourselves running in first gear for some of the Oray-Durango stretch.

[dkottum]

Might be good to reconsider the amount of gear in the truck and trailer you bring on those long trips, try to lighten the load significantly.

[r carl]

Originally Posted by FastEddieB

As a data point, my 2011 Flex with EcoBoost says this:

3.5L V6 EcoBoost engine

Your vehicle is designed to run on regular fuel with an octane rating of 87 or higher. For best overall performance, premium fuel with an octane rating of 91 or higher is recommended. The performance gained by using premium fuel will be most noticeable in hot weather or in severe duty applications such as towing a trailer.

So far, I've just run regular, to no apparent ill effect.

The computer will back off engine timing so you don't have an ill effect.

[carl2591]

very interesting info on towing and MPG..
however it might be helpful for all if you include.

year of TV
size engine, gas or diesel
rear end ratio
manf and sub name.. ie.. 2008 Dodge Ram 3/4 ton with cummins diesel

and other pertinent info cause a suburban with 4.10 mean less than knowing the year of that vehicle.

it just help compare apples to apples, so to speak.

[minke]

I am under the impression that high altitude 85 octane gas is the same stuff as sea level 87 octane and the different numbers are simply a consequence of measuring the octane at different atmospheric pressures.

[perryg114]

The need for Octane goes down as altitude goes up. This is if you don't have a turbo. If you have a turbo it will maintain the same boost no matter the altitude and you should use the recommended octane even at high altitudes. The only gas turbo tow vehicle that I know of is the F-150 Eco boost.

Perry

[pappy19]

On my Ford V-10, whenever possible, I use non-ethanol gas. Non-ethanol 87 is the same as 85 ethanol. In other words, non-ethanol is much better on engines and cat converters than ethanol. More power and better mileage too.

[carl2591]

Originally Posted by perryg114

3000 RPM is not going to allow that engine to produce much horsepower. Ask the dealer what a safe redline is for that engine and what the RPM is for peak HP. If you are climbing hills you need to stay at the peak HP to get up that hill. A diesel will be able to pull a hill at 3000 RPM but a gasser won't develop enough HP. It is ok to run a gas engine at high RPM. That is what they are designed for.

Perry

have to differ with the 3000 RPM being to slow to tow.. its not HP that get you up the hill with a load it torque and the engine may produce better torque at that RPM.

that the reason diesels are perceived to be better tow vehicles is the torque they produce, not the HP.

check a power curve to see the difference.

for example on a 5.3L V8 the max HP is at 5600 RPM (355HP) the torque on the other hand tops out at 483 FT Lbs at 4100 RPM, but in looking at the chart 2014 Chevy Silverado - Page 2 you can get torque of about 350 ft lbs at 3100 RPM so not all that far off.. so the poster running 3000 rpm in first gear is very plausible.

again its torque to the top,, more than HP..

[J. Morgan]

Horsepower is torque times speed.

Torque is twisting force, horsepower is how fast a job can be accomplished.

For example with a big long breaker bar I might be able to generate a thousand pounds of torque at 2 rpm, but I would be woefully inefficient at pulling an Airstream up a six percent grade at more than inches a minute.

It has become somewhat cliché to say torque does the work, time must be factored in, that is where HP comes into play.

A horsepower is 33,000 foot pounds of work per minute.

As a point of useful trivia, due to the way the formula works, horsepower and torque are always identical at 5252 rpm.

The 5.3 will pull a hill stronger at peak horsepower than at peak torque. The numbers say this is true as well as the seat of my pants feel.

[ROBERTSUNRUS]

Originally Posted by J. Morgan

Horsepower is torque times speed.

Torque is twisting force, horsepower is how fast a job can be accomplished.



The 5.3 will pull a hill stronger at peak horsepower than at peak torque. The numbers say this is true as well as the seat of my pants feel.

Hi, my Lincoln has a torque rating of 355 ft lbs at a very low [for a gas engine] 2,750 RPM. But if I can keep my engine spinning at around 4,000 RPM in second gear, it will climb mountains like crazy. Once I lose my momentum, I usually can't get it back. [300 HP]

I just checked and my horse power peaks at 5,000 RPM.

[perryg114]

Math don't lie. The transmision will deal with rpms. Peak hp will be the quickest way to the top. That is why I like a manual for weak 4 bangers. It is the only way to keep them at peak hp. Automatics are never at the right gear. With big engines this is not as big a deal.