6.4 hemi getting 22 mpg???

[Road_Phantom]

I was a little hesitant to buy a 2500 Ram with the 6.4 gasser, especially after reading the low mpg drivers in this forum were getting with theirs. however, I couldn't justify the price of a diesel for the low amount of yearly driving we do.
If the idiot gage in the truck was anywhere near accurate, I was getting 22 at 60 mph hwy on a recent trip through hilly Pa.
I can only guess that the low mileage posted by other drivers was because of higher speeds, a real gas killer.
We will be making a trip from Pa to Tx this coming weekend. This time we will do a comparison on paper to see if it comes anywhere near 22. I will post that Sunday.

[ib516]

Slowmover wrote:


Can a 6.4 get 22-mpg. I’d take that bet.

Here's a video I made Where mine is getting 21-22 (in the cold) on a flat highway, with a bit of a side wind at 65 mph, and that's with 4.10s and the "old" 6 speed auto.

[Slowmover]

Thanks, Grit Dog. You’ve quite a few good ones yourself.

The MX13 Paccar in this 2019 579 Pete cruises 66-mph at 1150-1200 rpm. 12-speed Paccar (Eaton-sourced) automated Manual. The only time I drop to the sevens in a trip is loaded to gross and/or terrain.

On the TT the plan is to make the repairs and improvements necessary to hit 17 on the flatlands, no wind. That’s at the usual 1,700-rpm and 58-mph. 17k usually and 63’ long.

Whether I hit that or not isn’t as important as my knowing I’ve expended every effort of which I’m capable to minimize fuel burn. Understand that I’ve also planned HOW to make the drive. Lowest friction. As an outgrowth of a living as a driver, putting depth to the details to keep those tenths. (As it isn’t new to me, it isn’t “work”; what I assume is the barrier for most).

Big truck or vacation rig. Some planning and some discipline.

Were the roads as they were in the 1960s and 1970s without the explosion of truck traffic and now the wholly-unexplained phenomenon of WHO THE HELL ARE ALL THESE PEOPLE CROWDING THE INTERSTATES WHEN THEY SHOULD BE AT WORK, operating the vacation rig was less work. More enjoyable. Better.

In the earlier post I noted that solo miles can underwrite vacation miles.

In a technical sense, why is there any discrepancy between town & country driving? Most report a large change. THAT is where to start. There shouldn’t be one of real significance.

My highway AVERAGE is 25. On that bet I got my city AVERAGE to 22. (And as I said, I’m not serious. That Cummins engineer was into the 40s).

Plans: combine errands. Never idle, and never stop. Use Mapquest for best order routing (like UPS delivery; no left turns, etc).

The average RVer travels 5k annually. At 10-mpg with $3 fuel that’s the need to save $100 worth of fuel monthly. $25/week.

Use FUELLY or other to record every gallon. One is looking for a PERCENTAGE CHANGE. That’s the ticket.

It’s not the absolute number. Just bettering what we already have.

Can a 6.4 get 22-mpg. I’d take that bet.

.

[ppine]

philh is right. Everything else is made up.

[Me_Again]

azrving wrote:


2 strokes rock!! 🙂

Run it is 2200 RPM and shift up, pick it up at 1900 RPM in next gear and run it to 2200 again. Just the opposite going the other direction, drop to 1900 climbing a grade and shift down, now at 2200 again.

Chris

[azrving]

Me Again wrote:
I drove this Titan 90 Chevy from 1976-1979. Daily trips were are half empty at 25K GVW and half with 7500 gals of fuel for 72K GVW, once in a while with 8500 gals for 80K GVW. Wheel base of the combination(think Federal bridge weight laws) prevented running routinely with the trailer filed to 8500.

Over all mileage was 4.5 MPG. 8V71 350 Detroit with 13 Roadranger was not very fuel efficient.

So 9 or 10 MPG with modern trucks looks pretty good.

2 strokes rock!! 🙂

[Me_Again]

I drove this Titan 90 Chevy from 1976-1979. Daily trips were half empty at 25K GVW and half with 7500 gals of fuel for 72K GVW, once in a while with 8500 gals for 80K GVW. Wheel base of the combination(think Federal bridge weight laws) prevented running routinely with the trailer filed to 8500.

Over all mileage was 4.5 MPG. 8V71 350 Detroit with 13 Roadranger was not very fuel efficient.

So 9 or 10 MPG with modern trucks looks pretty good.

[mtofell1]

With 82K on my 2014 Ram 6.4 Hemi I'd say the Fuelly average of around 12 is very accurate. Winter fuel, having a lead foot and stop/go driving all really have an impact. I can average upper teens or maybe even 20 for long periods if it's flat and no wind, and I drive 55-60. Towing my 11K 5th wheel I'm usually between 7-10 depending on terrain. Still better than the old Ford 460 mentioned a few posts up on it's best day.... empty. Pretty impressive progress made in the last couple decades.

[memtb]

Many years ago, I was told by an older (much) gentleman, “ there are two things a man will lie about.... their fuel mileage and their sex life”! The engineer/computer geek that designed the fuel mileage computer for the Rams, certainly fits this description! :B

[Grit_dog]

^ very insightful Slowmover. Great post with good things to consider!
Thank you

[Slowmover]

It’s more than “learn about diesel”. It’s having a plan to reduce ANNUAL fuel burn so that VACATION miles are a wash by years end.

First, diesel has 1/3 more “power” per gallon. So the price variation between gasoline and diesel is up against the diesel upgrade cost. These days, diesel doesn’t pay for itself until the trailer is 14K or heavier.

So buy a better trailer. As that’s the better plan.

And it’s not trailer weight that diminishes MPG. It’s the trailer shape. We can build a 3000-lb trailer that a 5500 will be unable to get above 50-mph.

I can run my 20,400-lb Peterbilt with an empty 53’ 12,000-lb trailer at just above 10-mpg at 66-mph. 13L engine. Sure, no headwind, light traffic, etc. Weight isn’t the problem. With up to 30k in the box I’ll still be pushing against 9 in favorable conditions.

If you want lower fuel cost, buy an aerodynamic trailer. There’s one brand of about five still around from the golden age. And one that’s ten years old with depreciation finished is better than these stapled boxes off the local dealers lot when brand new.

If I average 50% better tow mpg than you (while pulling a 35’ TT), maybe it’s because you’ve been looking at the wrong end of the equation.

Can a 6.4 hit 22-mpg? I can (and have) done that in city only with my CTD. On a bet from a Cummins engineer. (He’s serious, I’m not). So we know weight & shape aren’t at issue. It’s down to operator motivation.

As in my earlier post, one stacks the deck in ones favor. Tests.

But my experience on several vehicle forums is that no one has the maturity to change habits or challenge the 16-year old in the drivers seat. That’s confirmed by what I see year round and across the country out on the big road at 120k miles/year.

I’ve posted several times at length on HOW TO get free vacation towing miles. In my case, at my average MPG, it would be 5,000-miles FREE FUEL.

But every time, I hear excuses. And then back to the same echo chamber.

Retired? Reduced income? Fuel is still less than half the daily cost when it’s all toted up. But it’s the “fixed overhead” that CAN be changed.

Keep it simple: How many years will you travel? Last year, how many nights away? Vacation miles were? The total RV costs aren’t annual. They are THE NIGHTS ABOARD (only). Start there.

.

[ppine]

seaeagle2 wrote:
Isn't fuel mileage and heavy duty truck an oxymoron ? You can have mileage or cargo capacity, although I have to admit things have improved since my 1977 F250 with 460 and 4BBl. 6 mpg fully loaded with Kamp King camper, 6 mpg with empty bed...

Learn about diesels.

[trail-explorer]

Always hand calculate the MPG based on the odometer readings on the fuel you put in at fill up

I've had 5 vehicles with the MPG display on the dash, all of them (GM, Jeep, Subaru) display at varying degrees of accuracy compared to hang calculated MPG.

[ppine]

Fill your tank and record the amount of miles until the next time you fill up. Use the miles traveled and amount of fuel burned for the calculation.

My neighbor got 26 mpg on the read out with his Dodge 5.9 Cummins and a manual trans.
I have gotten 23.8 mpg with a one ton Ford 7.3 and auto trans. Those are measured numbers, not approx ones off the read out.

[seaeagle2]

Isn't fuel mileage and heavy duty truck an oxymoron ? You can have mileage or cargo capacity, although I have to admit things have improved since my 1977 F250 with 460 and 4BBl. 6 mpg fully loaded with Kamp King camper, 6 mpg with empty bed...