3.21 vs 3.92: The Last Word

[SnowBlaZR2]

Those weren't as appealing to me

Sure, because "best mpg the truck is capable of" wasn't the priority. You probably did what I did when deciding I didn't want the 33 gallon tank.

 

[theblet]

Sure, because "best mpg the truck is capable of" wasn't the priority. You probably did what I did when deciding I didn't want the 33 gallon tank.

Yea it really wasnt a priority when i was shopping. My truck has all the options and the color I wanted. I would have bought it no matter what gears it had. No big woop for me because I rarely tow.

 

[ferraiolo1]

Sure, because "best mpg the truck is capable of" wasn't the priority. You probably did what I did when deciding I didn't want the 33 gallon tank.

Didn’t want the diesel, or v6.

Wanted the hemi, and the best configuration for mpg the hemi was capable of. So 3.21s was the best option.


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[SnowBlaZR2]

Didn’t want the diesel, or v6.

Wanted the hemi, and the best configuration for mpg the hemi was capable of. So 3.21s was the best option.


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I didn't think you had the eTorque.

 

[Ninety-9 SE-L]

If you guys want Apples to Apples, you're going to need to test Apples to Apples.

I'm picking up my truck Saturday (granted, it won't be broken in). I plan to hang out in New Orleans and Pensacola for the day, then drive back to Tampa at night. I usually cruise around 71mph for hours at a time (just faster than the big rigs, but slow enough to get good mileage). I'll record a 100mi stretch and see what I'm able to get.

Conditions:
71mph cruise control late at night on mostly flat interstate.
100mi stretch without interrupting the cruise control.
3.21 EcoDiesel 4x2.
Record average mpg over that stretch

If anyone wants to repeat my method on the 3.92 EcoDiesel, be my guest. I do this kind of night driving regularly, so I know it's easy to go for 100s of miles on the interstate without touching the gas or brake. I'm making no guarantees, but I'm hoping to beat my 32mpg window sticker.

From this article below, he tested on a fully loaded Laramie 4x4 w/3.92, which was rated for 29 highway mpg, he managed to make about 30.6

I Drove 1,000 Miles on a Single Tank in the 2020 Ram 1500 EcoDiesel

Is 1,000 miles on a tank of fuel actually possible in the real world? Yes—and then some.

www.thedrive.com

Worth noting, the article mentions that the reason the 3.55 was replaced with the 3.21 was because the Gen 3 EcoDiesel makes its peak torque at 400rpm lower than the Gen 2. Basically, the Gen 3 breathes best at 1600RPM, which happens to be 71mph in my truck:

 

[Ninety-9 SE-L]

For the record:


The website is Spicer Transmission Ratio RPM Calculator if you want a quick plug and play

 

[djevox]

If you guys want Apples to Apples, you're going to need to test Apples to Apples.

I'm picking up my truck Saturday (granted, it won't be broken in). I plan to hang out in New Orleans and Pensacola for the day, then drive back to Tampa at night. I usually cruise around 71mph for hours at a time (just faster than the big rigs, but slow enough to get good mileage). I'll record a 100mi stretch and see what I'm able to get.

Conditions:
71mph cruise control late at night on mostly flat interstate.
100mi stretch without interrupting the cruise control.
3.21 EcoDiesel 4x2.
Record average mpg over that stretch

If anyone wants to repeat my method on the 3.92 EcoDiesel, be my guest. I do this kind of night driving regularly, so I know it's easy to go for 100s of miles on the interstate without touching the gas or brake. I'm making no guarantees, but I'm hoping to beat my 32mpg window sticker.

From this article below, he tested on a fully loaded Laramie 4x4 w/3.92, which was rated for 29 highway mpg, he managed to make about 30.6

I Drove 1,000 Miles on a Single Tank in the 2020 Ram 1500 EcoDiesel

Is 1,000 miles on a tank of fuel actually possible in the real world? Yes—and then some.

www.thedrive.com

Worth noting, the article mentions that the reason the 3.55 was replaced with the 3.21 was because the Gen 3 EcoDiesel makes its peak torque at 400rpm lower than the Gen 2. Basically, the Gen 3 breathes best at 1600RPM, which happens to be 71mph in my truck:
View attachment 130513

That’s pretty much what i’ve noticed also. My best mileage is between 70 and 75, or between 40 and 50.

 

[StuartV]

When I towed a trailer full of my stuff, moving from northern VA to SC, my rig weight was:

Steer Axle: 2940 #
Drive Axle: 6100 #
Trailer Axle: 8060 #
Gross weight: 17100 #

That is according to the CAT scale ticket.

I was mostly driving down I-95. I got 8.5 - 9 MPG (according to the Fuelly app, not the onboard lie-o-meter).

The funny thing is, even with a smaller, lighter trailer, I still only get 10 - 11, at best, when towing. Probably partly because I drove a bit slower than I normally would when I had that ridiculously heavy trailer.

(yes, I know was WAY over weighted. I will NEVER do that again. It was NOT fun)

 

[StuartV]

Maybe. Probably. But still fun. Actually I did put it in 4LO because I was on gravel and didn't want to sling it everywhere.

Turns out the metal basket was still around the root ball. I'd forgotten all about that being on there.

Yeah, when your tires are on grass, dirt, gravel, etc., I think you're pretty safe in assuming that the rear end gearing is not going to have any effect on what you can pull (unless you have some MAJOR weight somewhere in your bed or on your bumper). Even a 3.21 will spin the tires easily on a low-traction/loose surface.

 

[SnowBlaZR2]

If anyone wants to take a shot at the title.

 

[ClancyO]

On your wish list is a level kit, sounds like you don’t actually use your truck.

Level kit AND spacers - still on wish list. Reluctant to do them because I DO use the truck. Wdh and bags probably offset the level, but clearly don’t care enough about the results to spend the time & money.

 

[SnowBlaZR2]

Basically, the Gen 3 breathes best at 1600RPM, which happens to be 71mph in my truck:

Wonder where that is for the 5.7.

 

[ferraiolo1]

I didn't think you had the eTorque.

I have it. Generally keep it off as I find A. S. S. Annoying on all my vehicles.

That’s why I said if I was in stop and go traffic moving a small distance I could get 50mpg to your 37!


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[SnowBlaZR2]

I have it. Generally keep it off as I find A. S. S. Annoying on all my vehicles.

That’s why I said if I was in stop and go traffic moving a small distance I could get 50mpg to your 37!


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Do they not have stop signs or traffic lights where you live?

 

[ferraiolo1]

Not ones where I sit for more than a min. All smaller towns and mountains. Thus why the 3.21s are a good option for me


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[SnowBlaZR2]

Not ones where I sit for more than a min. All smaller towns and mountains. Thus why the 3.21s are a good option for me


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We have a few lights that last long enough for my engine to start back up. Sounds like I could do even better up there.

 

[Idahoktm]

On your wish list is a level kit, sounds like you don’t actually use your truck.

Are you saying a leveling kit will make his truck less capable?

 

[djevox]

Are you saying a leveling kit will make his truck less capable?

Watch out, if you had that leveling kit you might not be able to tow a paper clip.

 

[Ramroo]

Are you saying a leveling kit will make his truck less capable?

Yes

 

[BowDown]

That’s pretty much what i’ve noticed also. My best mileage is between 70 and 75, or between 40 and 50.

Me too, same speeds exactly