It's simple. The new 4.0L V6 has an aluminum block. The 3.8L has a cast iron block. The 3.8L will outlast the 4.0L V6 in abusive driving conditions like off-roading.

Given the choice between the two, Jeep was right to choose the 3.8L.

The Wrangler is not designed to be a speed demon. The 3.8L has plenty of horsepower and delivers torque at a lower point than the 4.0L (which is the more important measure on a Jeep). That is why the 3.8L will go in the new Liberty and not the 4.0L V6 that is in the Nitro (which is built on the same assembly line).

You do realize that the Nitro's 4.0L gives only 5hp more and actually delivers 5lbs. less of peak torque, right?

The numbers on the 4.0L-V6 Nitro are 255HP (@5800rpm) and 275ft-lbs (@4000rpm).
[Source: 2007 Chrysler Fleet Manual]

The numbers on the 3.8L-V6 Wrangler are 202HP (@5000rpm) and 237ft-lbs (@4000rpm).
[Source: 2007 Jeep Wrangler customer brochure]

By my count, that's 53HP & 38ft-lbs difference in peak values.

I think RUBICON was comparing the 3.8L-V6 to the 3.7L-V6 (210HP @5200rpm, 235ft-lbs @4000rpm).

The corporate mantra for the 3.8L-V6 is that it "maintains higher torque above 3400rpm than the 4.0-I6 it replaces". Translated, that means the 4.0-I6 had more grunt at lower rpms than the minivan engine. Duh. My butt tells me that!

My sources tell me a variant of the 4.0L-V6 (w/ a cast iron block?) is already being considered for the uninspiring 3.8L-V6 minivan engine. If not, we'll have to wait for the new "Phoenix" engines due in 5-6 years...

Having driven the 3.8L-V6 in a 2007 JK Unlimited with both a stick & an auto, saying it is "uninspiring" is a complement.

BTW, if you can spare about $4000 and some wrench time, you might be able salvage your new JK engine. Avenger Superchargers is making a blower for the 3.8L-V6 --sure to be good for a 40-50% improvement in numbers.

My bad... when I looked up the specs on the Nitro something got switched and I was looking at the 3.7L specs not the 4.0L specs.

Anyway, I would rather have the cast iron block which is available today than the aluminum block. IF a cast iron block of the 4.0L becomes available then that might be an option. But right now that is just speculation.

Uninspiring maybe, you want inspiring in a Wrangler you drop the top, go off-roading... not try to do stoplight to stoplight races with the guy in the Viper next to you.

Believe me, I like speed and power... I love the HEMI under the hood of my Commander. But I also realize that it is not applicable for every car. My Cherokee goes along just fine with its 190hp.

It is sort of like people who whined about rough rides in an SUV which lead to nearly everything having IFS and most vehicles going to IRS too. People need to realize that a vehicle has different purposes. If I want a luxury SUV that can go fast but do a bit of off-roading I would go with my Commander. If I want open air fun or even more off-roading I would get a Wrangler. If I want speed I would get a Dodge Charger SRT-8. Granted I know everyone might not be able to afford multiple vehicles but you choose a vehicle that does the things you want the most, not expect it to do EVERYTHING! IE, don't expect your Wrangler to be quick off the line. The old 4.0L never was it just delivered torque and snapped your head back to make it feel like you were going fast.

You also have to remember that the CJ-7s & YJs (thru '90) had the very torquey 4.2L-I6. Stump pulling & inspiring.

The '91 Wrangler then got the 180HP (...eventually 190+HP) 4.0L-I6 which --in 1991-- had better HP than virtually every other V6 and many V8s, and was clocked by a truck mag at a 8.0sec 0-60... faster than any other truck except a LM002 and the Cyclone & Typhoon. It had a little less low end torque than the 4.2L, but still had grunt and felt... INSPIRING. So ahead of its time, that it lasted thru 16 years of Wrangler production with few complaints.

Now we've got a minivan transplant in a heavier JK that is so smooooth, it has lost all its snap and inspiration... with even less low end grunt.

I don't need a drag racer, either, but when Saturn Vues, Ford Edges and Suzuki XL-7s are getting 250HP+... it's hard not to criticize DCX's engine choice.