4.0 compared to 3.8
12-20-2011 | 09:30 PM
#11
JK Enthusiast
Joined: Mar 2009
Posts: 304
Likes: 2
From: Texas
I had a 97 4.0 manual, a 08 manual 2 door, and now a 11 manual 4 door. Honestly, no comparison between the 4.0l and 3.8l.
My 97 had 33's with 4.11s.. It was okay under 50, above that was a chore and it did terrible on long trips. I averaged around 9-12 mpg.
My 11 with 3.73 and rubi tires just did a 600 mile round trip this past weekend, driving above 6000 ft almost the entire time.. Held 75 without any issues and I got 21.9 MPG average.
Anyone who says that the 4.0 is better isn't taking into consideration that the JK weighs a lot more than a TJ. Put that 4.0 in a 4 door and you will be hating it. The torque is better at any point in the rpm band with the 3.8 than the 4.0 as proven with dynos. Just my $.02
My 97 had 33's with 4.11s.. It was okay under 50, above that was a chore and it did terrible on long trips. I averaged around 9-12 mpg.
My 11 with 3.73 and rubi tires just did a 600 mile round trip this past weekend, driving above 6000 ft almost the entire time.. Held 75 without any issues and I got 21.9 MPG average.
Anyone who says that the 4.0 is better isn't taking into consideration that the JK weighs a lot more than a TJ. Put that 4.0 in a 4 door and you will be hating it. The torque is better at any point in the rpm band with the 3.8 than the 4.0 as proven with dynos. Just my $.02
12-20-2011 | 09:34 PM
#12
JK Enthusiast
Joined: Oct 2010
Posts: 495
Likes: 0
From: Dallas, TX
I've owned all three (4.0L, 3.8L, 3.6L).
Well, I put 100,000 miles on my 4.0L TJ Jeep (waving people to pass me), then bought a new 2011 Rubicon with 3.8L which was light years ahead of the 4.0L. Now I could almost drive on the Interstates. Then bought a new 2012 Rubicon with the Pentastar 3.6L - holy gee whiz, in a class by itself. I cruise at 80 mph and it makes the old 3.8L feel like a brick. Regardless of how good a deal ($) there is on those 3.8L Jeep's - they are a bad long term choice.
Well, I put 100,000 miles on my 4.0L TJ Jeep (waving people to pass me), then bought a new 2011 Rubicon with 3.8L which was light years ahead of the 4.0L. Now I could almost drive on the Interstates. Then bought a new 2012 Rubicon with the Pentastar 3.6L - holy gee whiz, in a class by itself. I cruise at 80 mph and it makes the old 3.8L feel like a brick. Regardless of how good a deal ($) there is on those 3.8L Jeep's - they are a bad long term choice.
12-21-2011 | 03:28 PM
#13
JK Newbie
Joined: Nov 2011
Posts: 78
Likes: 0
From: Pittsboro, Indiana
I still have my xj manual with the 4.0 and love it, but I like the 08 manual more. It is a bit of a personal choice though. The 4.0 is less refined and feels like a 'truck' engine in general terms and the 3.8 feels like a 'car' engine in that there is more refinement and much more linear power delivery. They are different so it is hard to say one is better than the other. Once you get used to the 3.8 it is easier to live with IMO.
12-27-2011 | 09:45 AM
#14
JK Enthusiast
Joined: Nov 2011
Posts: 205
Likes: 0
From: North Texas
Even with the JK being a heavier jeep I feel like the power is adequate. I'm completely satisfied with what it gives. I've been running 35s and 410 gears.
I've only had one other jeep with the 4.0 in an LJ, and I hated it. (power) Even it being a smaller lighter jeep it was pretty gutless. Off road I had no complaints. Wouldn't stay in od on the highway. It had 33s 4" lift and factory 373.
My jk won't pull hills in od, but then again most cars won't either, my other driver had always been a diesel, and now being a 6.7 ford diesel. So even after I get out of it and back to the jeep I'm happy with the jk power. My jeep had 90k on it so it's been tested and driven.
To answer question 4.0 doesn't compare to the 3.8 in my book.
I've only had one other jeep with the 4.0 in an LJ, and I hated it. (power) Even it being a smaller lighter jeep it was pretty gutless. Off road I had no complaints. Wouldn't stay in od on the highway. It had 33s 4" lift and factory 373.
My jk won't pull hills in od, but then again most cars won't either, my other driver had always been a diesel, and now being a 6.7 ford diesel. So even after I get out of it and back to the jeep I'm happy with the jk power. My jeep had 90k on it so it's been tested and driven.
To answer question 4.0 doesn't compare to the 3.8 in my book.