What kind of RPM's do you get? What about MPG?

deltabravo wrote:

JIMNLIN wrote:
Some folks use their trucks onboard DIC and report that as a mpg number.

Which in my experience is ALWAYS high. It's high on all the vehicles I've driven with a DIC.

I have a spreadsheet that I use to track fuel MPG. I record the DIC reading too. It's always about 1-1.5 mpg high on my current truck.

Same with the 5-6 new vehicles I've had with a DIC.
However my '03 2500 Dodge/Cummins NV5600 3.73 gears 2wd QC short bed with 330k miles for what ever reason has always ran up to 1.5 mpgs less than pencil numbers. I'm the type that resets at maybe tank number 6-8 after refilling. I know some reset on every refill.

When I hauled years back it was with one ton DRW and 460/454 carbureted engines and 4-6 mpgs was common at 55 mph. And that was pulling mostly under 26k-28k gross combined.
Blows me away at what some haulers are operating at 35k-38k declared gross combined and 9-11 mpgs is today with a one ton DRW....and doing it 7 days a week for 300k-400k miles (teams). Times have changes

JIMNLIN wrote:
Some folks use their trucks onboard DIC and report that as a mpg number.

Which in my experience is ALWAYS high. It's high on all the vehicles I've driven with a DIC.

I have a spreadsheet that I use to track fuel MPG. I record the DIC reading too. It's always about 1-1.5 mpg high on my current truck.

crasster wrote:
I've heard that 2400RPM and 7.5MPG is pretty standard. Is it wrong?

Depends on far too many factors to get an answer.

Make of truck
Model of Truck
Year of the truck
Engine the truck has
Gear Ratio the truck has
Is it 2WD or 4WD
Size of the RV
Weight of the RV
Are you driving in mountains are flat land?
Is there a head wind, tail wind or cross wind?


I get about 12mpg towing, RPM varies depending on if I'm on the flats or going up a hill. I downshift manually with my Allison to keep from loosing speed too much speed on hills.

If people get all worked up and concerned about fuel economy when towing (which in my mind is an oxymoron) they probably shouldn't be RV'ing since they are concerned about the expense.

The truck in my signature is a tool meant for a specific job - towing / hauling my truck camper. It's not my daily driver.

JIMNLIN wrote:
Many folks use a single tank refill as their mpgs. And some even short fill the tank so they can report high mpgs.....or use a older gazz station with a slopped driveway so the tank will short fill.
Some folks use their trucks onboard DIC and report that as a mpg number.

Also where one lives and travel on trips makes a difference. When we head to the Rockies its a 650 mile east to west straight run on US-412 from where I live in eastern OK on out to Raton, NM.
And from around 720' in elevation at home to around 7000' at Raton,NM. We've pulled it many many times with the rig or a car or just the truck. Going up will show poor mpgs vs coming back down.....as much as 4-5 mpg differences depending on winds.

The winds blows hard in the plain states much of the time. Prevailing wind are south to north. Many trees out here grow with their tops bent to the north. I've got some fantastic single tank mpgs going north on I-35 or other major US north/south highways. Average on several tank refills also eliminate those best tank figures.

I prefer a mpg average for three tanks (pencil numbers) at a minimum. More refills the better for a average mpgs.
Eliminates those best or worst single tank refill numbers.

I figured mine out over a 6,231 mile trip :)

6.4 Hemi and 4.10 gears. I just know a tank doesn`t last long.

Engine loading has as much to do with fuel efficiency as RPM's - maybe more so.
Even for a given engine, you cannot say it gets X MPG at a certain RPM.

ppine wrote:
If people with gas engines are towing at 1,900 rpms or 2,000 they are lugging their engines in my opinion.

The idea of 1,700 or 1,400 rpms makes even less sense if you want your engine to last.

My 2010 5.4L Torqshift auto/3.73 runs under 2k rpm on the flats. Rolling hills will cause a downshift to direct to run 2700~rpm or to 3rd to run 3800~rpm at 60 mph. At 106k miles, it still runs and looks new. No driveline repairs yet.

Many folks use a single tank refill as their mpgs. And some even short fill the tank so they can report high mpgs.....or use a older gazz station with a slopped driveway so the tank will short fill.
Some folks use their trucks onboard DIC and report that as a mpg number.

Also where one lives and travel on trips makes a difference. When we head to the Rockies its a 650 mile east to west straight run on US-412 from where I live in eastern OK on out to Raton, NM.
And from around 720' in elevation at home to around 7000' at Raton,NM. We've pulled it many many times with the rig or a car or just the truck. Going up will show poor mpgs vs coming back down.....as much as 4-5 mpg differences depending on winds.

The winds blows hard in the plain states much of the time. Prevailing wind are south to north. Many trees out here grow with their tops bent to the north. I've got some fantastic single tank mpgs going north on I-35 or other major US north/south highways. Average on several tank refills also eliminate those best tank figures.

I prefer a mpg average for three tanks (pencil numbers) at a minimum. More refills the better for a average mpgs.
Eliminates those best or worst single tank refill numbers.

The penalty is 40% over the TV loaded-same when solo at 55-60.
1970 or 2020
Gas or diesel.

The penalty is aerodynamic.

Diesel isn’t better or worse UNTIL you factor the fuel cost PER MILE.

Gasoline = $2,50
Diesel = $3.00

At my usual 58-mph/1,725-rpm flatland cruise, my average (not high or low) is 15-mpg.

In 100-miles that’s close enough to 6.5-gals diesel. 19.5-cents per mile for fuel.

That’s the same “fuel mileage” as burning (8) gallons of gasoline. Or, 12-mpg.



“Fuel economy” is in having a plan. Records.

1). The annual fuel budget is the context.
Reduce that (overall), and taking a trip isn’t expensive.

2). Control of vehicle use year-round (combined trips; no cold starts or idle time).

3). Constant use of cruise control on highway.
A speed that keeps one from lane-changing (62-mph, tops).

4). Trip plan. Stops known in advance.
Start time and end time are both early (to avoid traffic volume).

If this was a logic problem, no one would ask. But it’s America, thus it’s emotional. Getting used to daily spending more on fuel than one does in a week (is the hurdle).

It’s also become the land of bad drivers, almost without exception.

Failure to maintain adequate vehicle spacing is the glaring one. Neon.
A football field is about right for minimum distance. Solo.

Fail at this, and nothing else will matter.

Safety & Fuel Economy track one another almost 90% or more.
Bad FE is the same as unsafe driving, in other words.
(FE means tested. Combined versus solo where solo weight is only missing the trailer hitched. Not a number pulled from your ___. )

Tires and brakes should last 70k or more.
Tire rotation should almost be unnecessary.

““But, but, I don’t wanna do that!”

Yeah, I know. I have to drive among you.
Daily. Hundreds of miles

Your fathers & grandfathers were better drivers.
In that better society men LOOKED AROUND to ensure their end of cooperation.
That’s gone, now.

Keep records. Test. Formulate a plan. Use discipline.

.

Diesel Cummins 5.9 at 61-65mph highway
Small trailer, fold down to truck cap height 16-17.
23 foot HILO trailer, slightly higher than truck cap, 15-17.
Truck camper (very aero TC) pulling cargo trailer 15-17.
Towing in Rockies I have seen 20, but that is with a manual shift and coasting downhill a great deal. Hills that I can coast down always give me much better mpg with diesel because it is so over-powered/ over-torqued for hauling campers that the hills do not take a toll going up, and are free going down.
Better mpg in CO than in FL for sure.

The same thing with a gas motor, 10-12.

You are not stupid, you already know, and everyone reading, not everyone posting, knows that each person has unique mpg numbers, but if you read enough you start to have enough data to graph the numbers in your head and understand the bell curve aspect and what is normal, what is possible, and what is just bad.