An Engineer's Ultimate Guide To 3.21 VS 3.92 Axle Ratio

[Mountain Whiskey]

Interesting. Just read through the thread "At what RPM does your aftermarket exhaust drone?" It seems that the 3:92 crowd for the most part did not have troubles with drone. It was just when the MDS kicked in or trucks with 3:21 gears struggling to get up the highway that experienced the annoying sounds.

Hmmm. One more 3:92 advantage.

 

[BowDown]

I see in your signature that you have a 4X2 and it can’t be an equal comparison with 4X4, the window sticker will show a slight advantage for the 4X2 but in reality the 4X4 will have an even bigger difference (meaning worst mpg) than the window sticker mpg.

All the guys complaining about mpg are 4x4 trucks?

HSKR R/T said:
Where did you get your numbers from? I doubt anyone is getting 17-18mpg in city driving. Right now, I'm averaging about 15-16mpg displayed mileage in "city" driving.

And what he actually said was that he doubts anyone us getting 17-18 in city driving.
He was wrong

 

[Idahoktm]

Where did you get your numbers from? I doubt anyone is getting 17-18mpg in city driving. Right now, I'm averaging about 15-16mpg displayed mileage in "city" driving.

As for your blanket statement about people complaining in every other thread about fuel mileage, most don't specify what gears they have in most threads. And anyone complaining about gas mileage in a V8 powered 1/2 ton truck probably shouldn't be driving a truck.

I am getting 17-18 mpg in the city with 3.92 gears.

 

[KWKSLVR]

I am getting 17-18 mpg in the city with 3.92 gears.

So much of it really is how much lead is in your foot and how often you're locked into cruise. Road trips in our minivan are the perfect example. I'm about 4mpg higher than my wife.

 

[Scram1500]

Well, you have a point. It might belong to one of the girls but then it just wouldn't be right to park on top of it.

Hey do you think one of the FCA engineer geeks saw this and thought up the electric Ram Truck?

She's been parked on before, believe me

 

[HSKR R/T]

I am getting 17-18 mpg in the city with 3.92 gears.

What do you consider "city" driving? Stop light to stop light under 40mph, I find that hard to believe. If most of your driving is 45-65 mph on longer stretches where you can set cruise, that's not really city driving

 

[Idahoktm]

What do you consider "city" driving? Stop light to stop light under 40mph, I find that hard to believe. If most of your driving is 45-65 mph on longer stretches where you can set cruise, that's not really city driving

Why do you find it hard to believe? Is it because it doesn't align with your opinion?

On this particular tank of gas I'm at 17.3 mpg. I do have a 2 mile stretch of highway to get into town, but other than that Coeur d'Alene, Idaho (population 54,000) is mostly 25 to 35 mph roads. I did drive into the woods yesterday. By the time we got to our destination, I was at 16.3 mpg...it was 35 mph and all uphill from 2,000' to 4,000'. I gained all of the mpg's back on the downhill back into town. In a normal week, I drive an 82 mile round trip on the freeway and that accounts for ~23% of my driving for that tank of gas. On those tanks of gas, I'm normally at 17.5-17.7 mpg.

I usually avoid threads like this because they go absolutely nowhere, but I was bored and had a weak moment while reading some of the misleading comments.

 

[HSKR R/T]

Why do you find it hard to believe? Is it because it doesn't align with your opinion?

On this particular tank of gas I'm at 17.3 mpg. I do have a 2 mile stretch of highway to get into town, but other than that Coeur d'Alene, Idaho (population 54,000) is mostly 25 to 35 mph roads. I did drive into the woods yesterday. By the time we got to our destination, I was at 16.3 mpg...it was 35 mph and all uphill from 2,000' to 4,000'. I gained all of the mpg's back on the downhill back into town. In a normal week, I drive an 82 mile round trip on the freeway and that accounts for ~23% of my driving for that tank of gas. On those tanks of gas, I'm normally at 17.5-17.7 mpg.

I usually avoid threads like this because they go absolutely nowhere, but I was bored and had a weak moment while reading some of the misleading comments.

Thank you for the honest reply. Answers my question.

 

[german88]

Here's a real world comparison of 2 similarly equipped Laramie 4X4's, mine with 3.21 gears and "Idahoktm's" with 3.92 gears. I did the same drive as he this past week. (I did drive into the woods yesterday. By the time we got to our destination, I was at 16.3 mpg...it was 35 mph and all uphill from 2,000' to 4,000'.) Add to that two weeks worth of city driving dropping kids at school and running errands. Currently at 19.8 mpg. On a recent trip from Cleveland OH to Spokane WA I reset to zero and landed in my driveway at 21.3 MPG. I will admit my style of driving is more on the grandpa side and I never disable "start stop" since it works so seamlessly. Having driven with "Idahoktm" I would call his style more of a "Big Daddy Don Garlits" type!

 

[KWKSLVR]

Here's a real world comparison of 2 similarly equipped Laramie 4X4's, mine with 3.21 gears and "Idahoktm's" with 3.92 gears. I did the same drive as he this past week. (I did drive into the woods yesterday. By the time we got to our destination, I was at 16.3 mpg...it was 35 mph and all uphill from 2,000' to 4,000'.) Add to that two weeks worth of city driving dropping kids at school and running errands. Currently at 19.8 mpg. On a recent trip from Cleveland OH to Spokane WA I reset to zero and landed in my driveway at 21.3 MPG. I will admit my style of driving is more on the grandpa side and I never disable "start stop" since it works so seamlessly. Having driven with "Idahoktm" I would call his style more of a "Big Daddy Don Garlits" type!

View attachment 107933

Yeah, driving style definitely makes a difference. Even in my daily driven Camry that is a combination of 55mph highway and stop and go, my lead foot will get me 23/24mpg and my light grandpa foot gets me 28-30mpg. I hear people say, "It's a 4 banger, it doesn't matter how you drive it) and that's garbage. I'll get 36-38mpg on the interstate in that thing. My old 97 Trans Am would eclipse 30mpg on the interstate once it had full exhaust, or I could go sub 10mpg.

Your driving style matters. I don't care what gears you have. You're driving a brick and if you drive a brick with the pedal to the floor @85mph you're going to get garbage fuel economy.

 

[Idahoktm]

Here's a real world comparison of 2 similarly equipped Laramie 4X4's, mine with 3.21 gears and "Idahoktm's" with 3.92 gears. I did the same drive as he this past week. (I did drive into the woods yesterday. By the time we got to our destination, I was at 16.3 mpg...it was 35 mph and all uphill from 2,000' to 4,000'.) Add to that two weeks worth of city driving dropping kids at school and running errands. Currently at 19.8 mpg. On a recent trip from Cleveland OH to Spokane WA I reset to zero and landed in my driveway at 21.3 MPG. I will admit my style of driving is more on the grandpa side and I never disable "start stop" since it works so seamlessly. Having driven with "Idahoktm" I would call his style more of a "Big Daddy Don Garlits" type!

View attachment 107933

Hey, Don Garlits is a grampa.

 

[Mountain Whiskey]

Yeah, driving style definitely makes a difference. Even in my daily driven Camry that is a combination of 55mph highway and stop and go, my lead foot will get me 23/24mpg and my light grandpa foot gets me 28-30mpg. I hear people say, "It's a 4 banger, it doesn't matter how you drive it) and that's garbage. I'll get 36-38mpg on the interstate in that thing. My old 97 Trans Am would eclipse 30mpg on the interstate once it had full exhaust, or I could go sub 10mpg.

Your driving style matters. I don't care what gears you have. You're driving a brick and if you drive a brick with the pedal to the floor @85mph you're going to get garbage fuel economy.

Oh hogwash. I came frome driving a jeep. This truck slips through the air like a sparrow.


As for driving style, I drive it like I stole it and net 14.3 mpg. I'm on top of the world!

 

[Mr.Grid]

I have a question about Tow Haul with the Hemi. When you enable Tow Haul, does it only allow the transmission to go no higher than 7th gear?

 

[Mountain Whiskey]

I have a question about Tow Haul with the Hemi. When you enable Tow Haul, does it only allow the transmission to go no higher than 7th gear?

You still have 8th in tow haul mode on new Rams. The shift is just later so you hold higher rpms and it downshift when letting off the throttle for engine braking. I think there is a warning somewhere in the owners manual about not using it in slick conditions because of the engine braking making you loose traction.

Sorry, have to throw the trigger in there for this thread,,,, The tow haul mode will of course work better if you have 3:92 gears!

 

[Mr.Grid]

You still have 8th in tow haul mode on new Rams. The shift is just later so you hold higher rpms and it downshift when letting off the throttle for engine braking. I think there is a warning somewhere in the owners manual about not using it in slick conditions because of the engine braking making you loose traction.

Sorry, have to throw the trigger in there for this thread,,,, The tow haul mode will of course work better if you have 3:92 gears!

I’m switching from 545rfe in the 4th gen to the 8 speed in 5th Gen with the same 3.92 gear as prior. Tow haul in 4th gen kept you from going into convertor lockup when selecting tow haul I believe.

Does the 8 speed in 5th Gen do the same? Select tow haul and no convertor lockup?

fixed a mistake, got the gens mixedup

 

[Mountain Whiskey]

I’m switching from 545rfe in the 4th gen to the 8 speed in 5th Gen with the same 3.92 gear as prior. Tow haul in 4th gen kept you from going into convertor lockup when selecting tow haul I believe.

Does the 8 speed in 5th Gen do the same? Select tow haul and no convertor lockup?

fixed a mistake, got the gens mixedup

I don’t know the answer to that. I would have thought disabling the lockup would make the transmission run hot at highway speeds, especially under load.

 

[Mountain Whiskey]

What? 2 weeks has past and no one with 3:21 gears has been on here bragging how good their milage is while old Datsun pickups loaded with landscaping equipment are passing them asking if they need any help to get rolling.

We can't let the thread die. It hasn't cracked 1000 posts yet!

 

[c3k]

What? 2 weeks has past and no one with 3:21 gears has been on here bragging how good their milage is while old Datsun pickups loaded with landscaping equipment are passing them asking if they need any help to get rolling.

We can't let the thread die. It hasn't cracked 1000 posts yet!

Well, I was driving 80mph just this evening, and the pain of my mpg meter dropping below 28 (average) made me change display to the battery voltage. Now I've got to worry about those numbers instead...

 

[ferraiolo1]

3.21 bragging? All in the mountains doing 80.


Sent from my iPhone using Tapatalk

 

[HSKR R/T]

I have 3.67 rear gearing now.