5thGenRams Forums
Register a free account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members through your own private inbox!
everyone hate there 3:21 gears?
Mountain Whiskey
Spends too much time on here
- Joined
- Mar 2, 2021
- Messages
- 3,291
- Reaction score
- 7,667
- Points
- 113
- Age
- 59
Hey! I resemble that remark.We’ll, not sure about heuvos, but I guess 3.92’s are better for the overweight fast food crowd. I don’t have that issue
We 3.92 guys actually need the extra torque to get the truck moving with the extra heft of the giant huevos. Not like the little satchel the 3.21 wives carry in their change purse to let thier husbands touch occasionally.
i'm guessing it's a case of a small steak making the potatoes look big.
That's amazing. At least they give you some warning. Where is this?
Louhound88
Well-Known Member
- Joined
- Dec 30, 2020
- Messages
- 209
- Reaction score
- 152
- Points
- 43
- Age
- 37
Have to factor in tire size too. I have 35" tall tires, and I show 1900rpm at 90pmh.
Flat highway in louisiana. Surprisingly well paved road too, (for louisiana).
That's with CC on and set to 90mph.
Sonora Pass, Out of Sacremento.
Google Maps
Find local businesses, view maps and get driving directions in Google Maps.
Keep double clicking on the road and "drive up" it's like a cliff.
BowDown
Spends too much time on here
Incidentally, this was on the new part of I10 going east towards LA just outside Baytown.
Louhound88
Well-Known Member
- Joined
- Dec 30, 2020
- Messages
- 209
- Reaction score
- 152
- Points
- 43
- Age
- 37
Also, just because some 3.21 final gears line up with 3.92 finals gears doesn't mean that 7th and 8th respectively perform the same.
Engine RPM through transmission, equates to same driveshaft RPM. Change comes with the rear dif ratio which means the 3.92's wheels rotate one time for every 3.92 turns of the driveshaft.
Takes 3.21 revolutions of the driveshaft to equal one wheel rotation for 3.21 truck. and 3.92 for one wheel rotation for 3.92. That's cool and all, but the engine output doesn't change. The peak horsepower still hits at the same engine RPM and the torque still hits at the same RPM.
3.92 shortens the time it takes to reach that peak engine performance RPM. At the sake of distance travelled. This equates to a different "feel" with the 3.92 than the 3.21, because the revs jump quicker you end up with more wheel to road response.
All that said, I spent way too much time making a spreadsheet calculator to give wheel RPM and traveling speed (mph) based on the two axle ratios and final drive ratios. Based on tire size.
5500RPM seems to be the realistic top RPM you can hit stock. I've gotten close to 6K before, but it's not too easy. But at that engine RPM you can see on stock tires where the trans shifts. Both on stock tires and even loading you'll be in 3rd as you're crossing 60mph. 3.21 will hit the speed limiter (104mph) in 4th gear. 3.92 will do it just shifting to 6th.
In the picture I've attached i'm showing 2000RPM with 34.5" tall tires. It's a fine line with my tires as they're heavier, but I can cruise in 8th with CC on at 2krpm around 92. Beyond that it'll shift to 7th just because the tires weigh more and it needs the extra torque from a higher RPM in 7th to keep me at speed.
Engine RPM through transmission, equates to same driveshaft RPM. Change comes with the rear dif ratio which means the 3.92's wheels rotate one time for every 3.92 turns of the driveshaft.
Takes 3.21 revolutions of the driveshaft to equal one wheel rotation for 3.21 truck. and 3.92 for one wheel rotation for 3.92. That's cool and all, but the engine output doesn't change. The peak horsepower still hits at the same engine RPM and the torque still hits at the same RPM.
3.92 shortens the time it takes to reach that peak engine performance RPM. At the sake of distance travelled. This equates to a different "feel" with the 3.92 than the 3.21, because the revs jump quicker you end up with more wheel to road response.
All that said, I spent way too much time making a spreadsheet calculator to give wheel RPM and traveling speed (mph) based on the two axle ratios and final drive ratios. Based on tire size.
5500RPM seems to be the realistic top RPM you can hit stock. I've gotten close to 6K before, but it's not too easy. But at that engine RPM you can see on stock tires where the trans shifts. Both on stock tires and even loading you'll be in 3rd as you're crossing 60mph. 3.21 will hit the speed limiter (104mph) in 4th gear. 3.92 will do it just shifting to 6th.
In the picture I've attached i'm showing 2000RPM with 34.5" tall tires. It's a fine line with my tires as they're heavier, but I can cruise in 8th with CC on at 2krpm around 92. Beyond that it'll shift to 7th just because the tires weigh more and it needs the extra torque from a higher RPM in 7th to keep me at speed.
Attachments
Louhound88
Well-Known Member
- Joined
- Dec 30, 2020
- Messages
- 209
- Reaction score
- 152
- Points
- 43
- Age
- 37
Ah ok, yeah I was just on the other side of the state line then.
Idahoktm
Spends too much time on here
Here's the chart I used. I just extrapolated the data to get the rpm's for 100 mph. I'm assuming this chart was based on 32" tires.
Louhound88
Well-Known Member
- Joined
- Dec 30, 2020
- Messages
- 209
- Reaction score
- 152
- Points
- 43
- Age
- 37
Yeah, looks about like what I'm getting. Setting tires to real height of 31.8" and using 1925.517 RPM I'm getting 84.7mph. Same RPM the 3.92 will be at 69mph.
At 2360 rpm in 8th gear the same size tire will be at 104mph. 2300rpm at 101mph. For 3.21 that is.
Bump it to a 34.7" tire and at 2000rpm you'll be around 96mph in 8th. 2100rpm would give you 100.8mph at that tire size.
But whether the engine is in it's torque range needed to cruise at 96mph @ 2000rpm and 35"s, that's another story. I can cruise at 92 in 8th, but it will be sensitive. I rarely try to cruise at 92mph though. Usually I limit myself to 80 or 85mph. Keep me around 18mpg and less than 2krpm so my exhaust is quiet.
Idahoktm
Spends too much time on here
Enough with the math.
You guys need to get out and put the pedal to the metal and give us some real world numbers.
I enjoy hammering the gas as much as the next guy, but the days of going 100 mph on the street are well behind me.
Dewey
Spends too much time on here
Not to mention posting pics on a public forum greatly exceeding the speed limits just might self incriminate you. I’ve seen it happen.I enjoy hammering the gas as much as the next guy, but the days of going 100 mph on the street are well behind me.
I don't disagree with you, but at long as you can't tell where he was, there's no way to prove he wasn't on a track or some abandoned air strip.Not to mention posting pics on a public forum greatly exceeding the speed limits just might self incriminate you. I’ve seen it happen.
Idahoktm
Spends too much time on here
Not to mention posting pics on a public forum greatly exceeding the speed limits just might self incriminate you. I’ve seen it happen.
Another good reason to turn off location tagging on your camera app.
BowDown
Spends too much time on here
Not to mention posting pics on a public forum greatly exceeding the speed limits just might self incriminate you. I’ve seen it happen.
BowDown
Spends too much time on here
Has never been on but In case anyone is wondering, my real name is Mountain Whiskey
Dewey
Spends too much time on here
Hey pretty sure I self incriminated myself with this disorderly conduct with a motor vehicle awhile back.
BowDown
Spends too much time on here
Mountain Whiskey Jr, is that you?Hey pretty sure I self incriminated myself with this disorderly conduct with a motor vehicle awhile back.
View attachment 138340
