JPop

Sure thing.

With an automatic transmission you have some slip, in round numbers about 10%. You also have in most modern vehicles with an automatic transmission a lock up torque converter. This eliminates the slip of an automatic transmission when at cruise speeds. Whenever there is extra load placed on the drivetrain the converter will unlock, increasing engine rpm and placing more power to the wheels.

With the advent of the new OD gears in both the manual and automatic transmissions, they are much closer and the automatic is now running a steeper OD gear. With roughly about a 5% difference in OD gear sets, and 10% in slip the automatic is straddling where the manual transmission is. That's a ton of improvement, and dropping into 4th gear with an automatic transmission now won't send your rpms through the roof. Even better is double kick downs are going to be more palatable as well.

Hope that helps!

JPop

Good, that's about where it should be as things are based on actual tire size.

JPop

Yeah, pick the wrong gear set with an auto JK before the 2012 and you were hosed. The flatter torque curve and more power at lower rpms will make the Pentastar gear sets a lot more forgiving.

JPop

knight1000

JPop. Thank you for taking the time to do this.

IV.Sleepy

So are you telling me the 2012 can run 37's with the 4.10 and if you throw an exhaust and intake on it, it will do pretty decent? - add to the torque curve.

JPop

For my tastes that would be a little less than ideal, but doable. At the same time it wouldn't put me off from doing 37s until I had gears either.

JPop

Here's at least a pretty chart which matches up with the one for the 3.8l. I'll edit things as time goes on, but I'm certain this is very close.

joe002

Just for comparison could you post (here) the charts for the 07-11s?

JPop

The charts for the 3.8L are in the FAQ, but here's a copy of them. The charts for the 3.8L and the Pentastar are virtually the same for the manual transmission as Chrysler dropped some juice out of the OD gear. The automatic is where the huge gains are and personally it's enough for me to forego a manual transmission this time around.