3.92 vs 3.21

[Ram408]

I have a 2016 Ram CC hemi 4x4 Sport with the 3.21 rear. At 75mph on flat roadway, in 8th gear, my engine is purring along at approx 1650rpm’s. I have yet to order a 2019 limited and I’m split on which rear to get. Could any of you that already took delivery of your trucks, tell me what your engine rpm’s are at 75mph? I’m so curious to see how much higher it will be on a 3.92 geared truck. Thank you so much for any help!

 

[Zeronet]

Roughly 20% higher RPM. Simple math. 3.92 is about 20% more than 3.21. The rest of the drivetrain is basically the same.

 

[firecadet613]

I'm about 1650-1700rpms at 75mph. Very pleased with the 3.21s, although I will say I was going back and forth before I ordered and even after I took delivery. It took a long roadtrip for me to be fully sold on the 3.21s.

 

[Jus Cruisin]

The only reason I would go with the 3.92 would be if I was looking to max towing capabilities. Or if I was looking at putting some 37's with a lift. Putting 3.92's in it surely doesn't make them a race car by any means.

 

[19llhpb]

I will take a run in my truck here after bit and let you know the rpm’s of a 3:92. I am going to get a lift and 35” tires hence I got the 3:92’s. If my calculations are correct, running the stock 275/55/r20’s with the 3:92’s would be equivalent to a 3:58 rear axle ratio with 35’s. So I will still be ‘torquier’ so to speak than the 3:21’s stock. If that makes sense.

 

[SpeedyV]

Putting 3.92's in it surely doesn't make them a race car by any means.

Race car, no. More responsive off the line, absolutely!

 

[19llhpb]

Ok, here we are. ‘19 Ram with 8 speed tranny and 3:92’s. Mph and rpm’s in 8th gear.

55mph 1500rpm
65mph 1750-1800rpm
75mph 2025-2075rpm

 

[19llhpb]

Race car, no. More responsive off the line, absolutely!

Yes, 3:92’s definitely more responsive off the line and in highway passing, when compared to a 2015 Ram Hemi with 3:21’s.

 

[Jus Cruisin]

Race car, no. More responsive off the line, absolutely!

Relative to the standard rearend, that's about it..... They'll still get dusted by have the vehicles on the road.....

 

[SpeedyV]

Relative to the standard rearend, that's about it..... They'll still get dusted by have the vehicles on the road.....

Well...obviously. It's a truck.

 

[Neocane]

Well...obviously. It's a truck.

Haha!

 

[Duane]

Haha!

Haha!

To get the advertised highway mileage, you must get the 3:21s.