||09-27-2011 10:36 PM
The 4.0 was a good engine and many love it but the 3.8 actually put out a very little better numbers. The difference was the 4.0 didn't have to power the larger brick of the JK like the 3.8 and 3.6 has to. The mighty 3.6 even doesn't produce as great in the JK as many thought it would.
There really isn't a way to compare the 3.6 to the 4.0 for the same reason you couldn't compare the numbers of the 3.8 to the 4.0. The 4.0 would have to be put in the JK to get real wheel numbers where it counts in the end.