Regretting ordering 3.92 on my 22 Ram Ecodiesel and almost debating paying to downgrade to 3.21

[CheechDogg.0n37s]

I regeared from 3.21s to 4.88s but I do have 20x12s with 37s so I really needed to regear, in the OPs case he doesn't need to spend money if he is not going to add bigger wheels and tires.

Stay with the 3.92s OP, you need to give your new truck some time , spend those $2k on something else

 

[getrdun]

What is your fuel cost difference going to equate to in time to make switching the gears actually beneficial? How long before you turn profit. And these trucks turn into brick walls above 70mph anyways so the aerodynamics and drag will greatly reduce your fuel efficiency above 70mph anyways.

 

[scott lass 18]

Did you think about having it tuned or buying a tuner? I would think spending $300-$400 and gaining 2-4 mpg's would be the cost efficient way to go.

I did a tuner. Was well worth it. At frist was 9.0 city. And now 11.0 in city’s. Touck a while to happen. Use reg plus gas and have it runing a lot cooler . 2010 ram

 

[scott lass 18]

Wow, talk about another instance of "******* California".
I'm assuming its not as simple as getting it done from another state. Tbh how would California even know, I guess when it comes down to smog tests etc down the road?

Never had any problems smoging mine ! Only when oxgin. S enters went out ! Nobly use dodge one s ok don’t lost money on cheeper eBay ones ok. Lost 50.00 myself !

 

[JerryETX]

I'm not able to read all the replies so I apologize if I'm repeating what's already been said. You're not going to notice a big difference in fuel mileage with the 3:21. Your biggest issue is 80moh. You'll never get 29 mpg driving 80 unless it's with a huge tail wind and downhill lol. That 29 mpg number you heard of was probably at 65-70 mph. I would look at the big picture and give it a few months before doing something you may regret down the road.

 

[aj_g]

Never had any problems smoging mine ! Only when oxgin. S enters went out ! Nobly use dodge one s ok don’t lost money on cheeper eBay ones ok. Lost 50.00 myself !

I don't know the first thing about a tuner so I'd be ideally going through some shop and trusting them on it.
I was referring to the GDE stuff in that original reply, I'm guessing you don't have GDE?

 

[aj_g]

I'm not able to read all the replies so I apologize if I'm repeating what's already been said. You're not going to notice a big difference in fuel mileage with the 3:21. Your biggest issue is 80moh. You'll never get 29 mpg driving 80 unless it's with a huge tail wind and downhill lol. That 29 mpg number you heard of was probably at 65-70 mph. I would look at the big picture and give it a few months before doing something you may regret down the road.

Im seeing others in the replies get 30+ with the gen3's at 77+ mph, admittedly one was with GDE, but the other I'm not entirely sure about, trying to find more details.
Im not in a particular rush, just trying to see as many data points as possible.

 

[BossHogg]

I can run my 6.7 Cummins at 95 MPH and only turn 1600-1700 RPM.

So what axel ratios are you running to get 95MPH at 1700 RPMs? Axle ratio of 2:56 would get you there but that isn't offered.

1,700 RPMs will yield about 78 MPH with 3:43s, 71 with 3:73s, and 65MPH with 4:10 axle ratios.
1,600 RPMs will yield about 73MPH with 3:43s, 67 with 3:73s, and 61MPH with 4:10 axle ratios.

 

[Adam E]

The MPG difference between 80mph and 70 tells it all. Going to 3.21 is not going to get to 27mpg at 80. More likely 21mpg. And on anything other than a fairly long trip, the time saved isn't much. But, it's your money.

Considering I drive 60-65 around town and 70 on the highway, I'd be pretty tickled with 27+mpg instead of the 17-20 I get now.

Plus there is the added benefit of extending your life expectancy. I think I'll live 5 to 10 years long from the reduced stress after I moved out of the left hand lane.

 

[JerryETX]

Im seeing others in the replies get 30+ with the gen3's at 77+ mph, admittedly one was with GDE, but the other I'm not entirely sure about, trying to find more details.
Im not in a particular rush, just trying to see as many data points as possible.

10-4 hopefully you get it dialed in. It is disappointing not being happy with your truck.

 

[Docwagon1776]

So what axel ratios are you running to get 95MPH at 1700 RPMs? Axle ratio of 2:56 would get you there but that isn't offered.

1,700 RPMs will yield about 78 MPH with 3:43s, 71 with 3:73s, and 65MPH with 4:10 axle ratios.
1,600 RPMs will yield about 73MPH with 3:43s, 67 with 3:73s, and 61MPH with 4:10 axle ratios.

Maybe he's full brodozer with 44" tires...

 

[jimboschnitz]

Both my 2016 Eco and my 2020 Eco had 3.92 gears and the best fuel economy I've been able to get is consistent
24 to 26 on highway with an occasional 27 or 28 depending on a tail wind. A friend of mine has a 2015 with 3.55 gears and he complains of shifting between 7 and 8 when he runs 70 to 75 mph and encounters even small elevation changes. If you live in California I'm guessing you will experience even more downshifts with a 3.21 gear ratio because the engine will not be able to maintain consistent RPM's at 75 and 80 mph. My fuel economy is based on actual gallons per mile, not from the readout on the dash. The dash is consistently 1 to 2 mpg higher than actual. Someone in this string claimed 30 to 32mpg, I'm guessing that is based on the dash readout and not actual.

 

[jwrich4]

80mph = 2200 rpm and ~20mpg
75mph = Just over 2000 rpm and ~24mpg
70mph = I dont remember the exact rpm but its 27+mpg


Granted, SFLA is not known for big hills, but my 21 Bighorn ECO w/ 33gal tank gets 3-4 MPG better mileage at each of your listed speeds.
The question is how long would it take to recoup the money spent for the conversion in money saved in fuel?

 

[gypsy400]

You won't save ANY money by switching ratios. It's the aerodynamic drag at high speeds that are killing the fuel economy. Any speed higher than 65mph, aerodynamic drag is the #1 loss in fuel economy. And if you did actually save any fuel, it would take MORE than the lifetime of the truck to recover the cost of the ratio switch.

 

[WadXpress]

It won’t help the higher gears are the same between the 2 essentially. The difference is in the 0-45. I just swapped to 3.92s

 

[1stGen4me]

When buying a truck with a tow package vs non tow package there really isn't much difference in fuel economy but the big difference is the transmission will not be down shifting when come to any kind of a grade on the road. That's where a 3.92 ratio helps your fuel economy vs a tall gear ratio which hurts. Drive like you have a egg between your foot and the gas pedal folks. My 2018 Dodge truck gets between 19 and 22 on the highway and I don't expect anything better than that because after all it's big block going through the wind.

 

[leroys73]

It is a truck. If you want to use it as a truck and not a car the 3.21 gears would be disappointing. Don't expect miracles.

As probably mentioned, the advertised MPG, if accurate at all, is under ideal conditions with experts in getting high MPG.

 

[turkeybird56]

Your not wrong about the rpms(about 400 rpms less) but your overlooking the wind drag going at higher speeds which killing the fuel economy. These trucks have the aerodynamics of a cinder block

Aerodynamics, Rolling Brick, lmao. OP, gonna take a long time to recover the costs of switching, heck go to Dealer and Trade out for a 3:21, but honestly, the 3:92 just as good as the 3:21, it is more efficient, more about driving habits and conditions. At 80 mph, my HEMI makes that slurping sound that is the sucking of a straw, and I drop from 20+ to 17 mpg maybe, LOL.

 

[Regcabguy]

Hi, I had ordered my RAM with 3.92 ratio as I only seemed to come across the good articles at that time in which I learned that it will have a higher resale value in the future, better for towing, etc. I did see some mention of a negligible difference in mpg but thought nothing of it as the sticker did not update on the MPG at all after I selected 3.92. I had even picked up the bigger diesel tank because I wanted to be able to go on long trips while dreaming about the 29mpg thats advertised lmao.

I live in California, almost everyone and their mother drives 80mph here on the highways and most drive even faster. I live in a fairly rural area, I have to drive on the highways a fair bit in order to get most things.
In my first few weeks of testing, here's what I've noticed for mpg
80mph = 2200 rpm and ~20mpg
75mph = Just over 2000 rpm and ~24mpg
70mph = I dont remember the exact rpm but its 27+mpg

I did reach out to the service department at my local dealer and was told $2,750 + labor in order to switch to a 3.21 (guy sent me a detailed parts list as for the breakdown) and I'm following up with them now to see how much labor that would be.

In terms of switching over
Pros:
For the most part I can drive as I normally do and not have to worry about being inefficient in terms of diesel
Would be saving time as well as I'd be driving at 80mph instead of 70/75

Cons:
The upfront cost of course
Potential resale value in the future may be impacted but I dont like switching cars very often
Towing impact, I dont tow much now but it was just futureproofing


You may be calling me crazy but this is bothering me so much, like how did I look into every little detail and end up making this big of a mistake. Also, I am under the assumption that going to 3.21 will give me lower RPM's at 80mph, please correct me if I'm wrong.

Higher ratio would never be better for towing.

 

[drossday]

I ran an 811 mile round trip in April with a combination of fwy (75mph) county rural road, city and stop and go and my total trip mpg with my 3.92 and limited slip was 33.5mpg (and verified by fuel receipts)....