2021 1500 Limited 4x4 with 20' wheels 3:21 or 3:92

[Long Range]

I do very little towing if any, if ever did doubt it be anything over 6500 lbs. Live in a small town can drive across it in probably 8 min even if I hit a couple of lights. If I trade I'm hoping to improve my MPG from what I get with my 12 Laramie with a 3:55 gear 6 speed trans and stock 20" wheels. The only options I have for of course are 3:21 or 3:92. Thanks for any help.

 

[CG2742]

Depends on if you like going fast or not. The mpg difference for you may be super minimal. Both tow well.

 

[Graygoose]

If you had two identical trucks side by side, get the 3.92...find what you want and its 3.21, get it. I had 35" and 3.21 and it pulled like a dream and had plenty of power.

 

[ramffml]

There is no difference in MPG until the 3.21 can upshift into 8th and reach its final gear ratio. As long as the 3.21 cannot hit 8th (city driving), then both trucks have extremely close matched ratios available so neither truck has an advantage.

In other words; in the city, no difference. Only on the highway.

 

[jdolotina]

I have 3.92s and mainly drive in the city. I enjoy the grunt right off the line that I get with 3.92s. I purposefully looked for a truck with 3.92s. I had 3.21s in a 2013 ram and just didn't care for them. My city mileage has been up to 17.0 MPG in my 2020. Like others have stated the MPG difference between the two are negligible unless on the highway.

On the freeway with my 2013, it seemed to shift quite a bit every time I hit a hill. With the 3.92s in my 2020 I rarely shift even with cruise control and hit a hill. 4th Gen vs. 5 Gen, I would bet they have made some strides with shift parameters over the years, but I have been extremely happy with the 3.92s. Plus, you get the added benefit of having a higher tow capacity.

 

[ramffml]

I have 3.92s and mainly drive in the city. I enjoy the grunt right off the line that I get with 3.92s. I purposefully looked for a truck with 3.92s. I had 3.21s in a 2013 ram and just didn't care for them. My city mileage has been up to 17.0 MPG in my 2020. Like others have stated the MPG difference between the two are negligible unless on the highway.

On the freeway with my 2013, it seemed to shift quite a bit every time I hit a hill. With the 3.92s in my 2020 I rarely shift even with cruise control and hit a hill. 4th Gen vs. 5 Gen, I would bet they have made some strides with shift parameters over the years, but I have been extremely happy with the 3.92s. Plus, you get the added benefit of having a higher tow capacity.

Of course the 3.21 will downshift out of 8th sooner, it's running at 400 to 500 rpms lower than yours. That's the price you "pay": lower rpms, lower gas, better engine life. However, once the 3.21 is in 7th, its rpms will equal yours in 8th, so it will not downshift anymore often than yours will.

Tow capacity is a "paper win" only; especially with your loaded limited, I can tow more with my light bighorn and a 3.21 than you can with your loaded limited and 3.92. Your payload will determine what you can tow, not the 3.21 or 3.92 as gear ratio is very rarely the limiting factor.

Not saying you can't enjoy your 3.92 of course, but its not the saviour/feature that many think it is.

 

[jdolotina]

Of course the 3.21 will downshift out of 8th sooner, it's running at 400 to 500 rpms lower than yours. That's the price you "pay": lower rpms, lower gas, better engine life. However, once the 3.21 is in 7th, its rpms will equal yours in 8th, so it will not downshift anymore often than yours will.

Tow capacity is a "paper win" only; especially with your loaded limited, I can tow more with my light bighorn and a 3.21 than you can with your loaded limited and 3.92. Your payload will determine what you can tow, not the 3.21 or 3.92 as gear ratio is very rarely the limiting factor.

Not saying you can't enjoy your 3.92 of course, but its not the saviour/feature that many think it is.

While I do agree with a majority of what you have said, I beg the differ on this statement "However, once the 3.21 is in 7th, its rpms will equal yours in 8th, so it will not downshift anymore often than yours will."

I will agree that if you have a 3.21 gear limited to 7th and a 3.92 set to 8th on the same stretch of highway at say 75MPH with cruise set, both trucks should downshift at the same time to the next lower gear as you mentioned the final gear ratios are almost identical. However, if you run the same set of trucks to shift as they please without gear limiting, then the 3.21 will shift more frequently than the 3.92s on the same stretch of highway at 75MPH.

I have had both gear ratios and travel the same set of highway and the 2013 I had with 3.21s would shift to 6th every time I hit a moderate hill with cruise control set at 75MPH. Fast forward to the 2020 I now have and the same stretch of freeway at the same speed with cruise control on and it doesn't shift but maybe twice over a 200 mile journey. If it does shift, it will shift to 7th. Sure, lower gas, better fuel economy and lower RPMs means longer engine life, but every shift in a transmission can cause wear. So is it safe to say my transmission would last longer than yours if we were driving identical highway routes, identical trucks, but with different rear axle ratios because mine would shift less? The stretch of highway I have as reference is I-20 between Shreveport, LA and Dallas, TX. I have small hills throughout the entire trip and my 2013 shifted far more frequently than my 2020.

Both gear ratios bring pros and cons. I just happen to fall more in line of the pros for the 3.92s. Just as you mentioned, on paper everything is close depending on transmission gear and rear axle gear, but the real world for me, the 2013 was a truck that shifted entirely too much on the highway.

City driving between both trucks, I haven't noticed anything different.

 

[ramffml]

While I do agree with a majority of what you have said, I beg the differ on this statement "However, once the 3.21 is in 7th, its rpms will equal yours in 8th, so it will not downshift anymore often than yours will."

I will agree that if you have a 3.21 gear limited to 7th and a 3.92 set to 8th on the same stretch of highway at say 75MPH with cruise set, both trucks should downshift at the same time to the next lower gear as you mentioned the final gear ratios are almost identical. However, if you run the same set of trucks to shift as they please without gear limiting, then the 3.21 will shift more frequently than the 3.92s on the same stretch of highway at 75MPH.

Yes, again, that's because the 3.21 will be running at 400 to 500 rpms lower.

You're basically saying: because truck A has an overdrive, it will have to downshift more often on the freeway than this other truck B which doesn't have an overdrive. It's not a "con" or a negative, what's wrong with an extra downshift every once in a while? The whole point is to reduce RPMS and increase MPG wherever it can. If you get to a point in the road where it's getting really bad and constantly downshifting (maybe lots of steep rolling hills), the gear limiter gives you the option to drop down to 7th and now you don't have the extra downshifts anymore whatsoever. I don't understand the problem here, it's all benefit as far as I'm concerned.

So lets not fear the extra downshift anymore than we should fear going from a 6 speed transmission to an 8 speed. There is a lot more shifting in an 8 speed vs a 6, I don't think you'll find one person that actually thinks the 6 is better to own simply because there is less shifting. Heck, I'm dying for Ram to put a 10 speed in, can't come soon enough.

As for whether the transmission would last longer; I really have no idea. I don't think there is any hard data on this. One can just as easily say that your engine will die sooner because it's revving higher rpms all the time on the highway. I really don't know, but it's not something I'm worried about either. I just get in and drive and am amazed at how low my truck revs everywhere I go. It feels like it's just idling on the freeway for the most part.

 

[ramffml]

Oh, one other thing WRT to extra shifts; the other thing to keep in mind is that in the city, it's your truck that's more busy with extra up/down shifts. Because you have shorter gears, you will hit 3'rd/4th/5th faster than I will, for any given speed.

 

[Mpgrimm2]

I've found with my driving style, the more capable the engine/gear ratio, the heavier my foot and worse the mpg... Comes with the fun Factor...

>> SW VA/Appalachian Mtns area <<

2013 Express 1500 CC 4x4/v8/6spd/3.21
= terrible mpg ~ 14/17mpg avg on a good day
(Owned for 4mos)

2013 SLT 1500 CC 4x4/v6/8spd/3.21
= respectable power for v6, Mpg and handled all my occasional medium tow/haul needs. Some gear hunting when towing near capacity around 70-80 mph ~ 19/23 mpg (24-25 on long hwy trip & light pedal)
(Owned for 4.5 yrs 63k mi)


>> Western SC/ Somewhat flat area <<

2018 Laramie 1500 CC 4x2/v8/8spd/3.21
= Very good power, decent mpg, no complaints whatsoever. ~ 18/21 mpg (22-23 mpg my best)
(Owned for 2.5 yrs 53k mi)

5th gen 2019 Laramie 1500 QC 4x2/v8/8spd/3.92 etorque
= Quick, will get out of it's own way in a hurry, Ok mpg, but I find I have a heavier foot now. I drive 35 mi to work each way so I see the impact at the pump. Fun factor is certainly there. ~ 17/20 mpg (21/22 mpg best I can get on a trip... See below)
(Owned 7mos 8800 mi)

From my current trip being light on the pedal running across SC (50/50 interstate & Hwy driving 72mph/62 mph & Lt traffic)....


M² Mods.
(via Tapatalk App)

 

[Burla]

Yeah, the 8 speed will be the main factor in a positive direction for you. Or if you have room keep your truck and get a smart car or some ****.