Almost there!

CAN'T WAIT!!!

 

Its a Jeep, why do people feel the need to fly down the hiways and biways of America. Its the perfect vehicle to ENJOY these very roads that most take for granted cause they are too busy slurpin the espresso and talkin on the phone to even notice. Sit back, relax and take in the grandeur of this great land. A Jeep will take you anywhere in this country on or off-road. The 3.8L is fine for this.

 

"It was still based on older tecnology though as I originally stated, including a tall cylinder block with longer stroke and shared some architecture with the old Typhoon six from the early 60's, which is why it had good low-end torque but lacked the ability to rev freely and provide power at higher revs, unlike the JK."

The reality is that the 3.8 actually has a LONGER (just barely) stroke than the 4.0. The smaller displacement actually is because the bore of the 3.8 is slightly smaller than the 4.0. Any difference in torque curve that's not related to displacement is based on the airflow characteristices, engine management, camshaft profile and valve timing rather than the relative size of the bore vs. stroke.

The torque curves of the 3.8 and 4.0 aren't all that different, but the 3.8 does make slightly more torque that the 4.0, but you have to rev the motor to get it.

The main problem with the 3.8 is that it is undersized for something like a 4-door Wrangler, especially with the four speed automatic (the primitive tranny is also a major part of the problem). Stick a stock 4.0 in a 2010 Unlimited and you'll find it's just as underpowered.

The new Pentastar looks to be a superior motor (on paper) to either of the above, but it's biggest advantage is going to be much more horsepower at higher RPM. (it will also likely provide better economy) Chrysler claims that it will produce 90% of peak torque at 1800 RPM, so it will be flexible and might actually have marginally more grunt that either of the above motors. But it will be a mistake to think it's going to have the grunt of a V-8.

If you're unhappy with the passing power of the 3.8 and zero to sixty acceleration is important to you, and you're willing to rev the motor to 7,000 RPM to get it, (which admittedly might be fun) I think the new Pentastar is likely to cure the problem. But, if towing a small boat uphill with in an automatic 4-door with 35's is not likely to make you happy, unless Jeep also fits the Wrangler with a more modern tranny.

 

I sold my 4.0L TJ back in '06 in order to order my '07 JK from the factory. I didn't really get to drive one previous to ordering, until about two months later (ordered it in August, they didn't start showing up on lots until the end of the year). Once it finally arrived in December of '06, I was completely happy with the engine and 6 speed manual tranny, with the 4.10 gearing. My JK would outperform any of my previous TJs, I was always disappointed with the 4.0L anywhere on the street or highway, they always seemed underpowered to me. The only thing I didn't like at first, and still don't, is the delay of the drive by wire, but there are numerous ways to address that issue.

 

I have an 07 with 4:10's and the Auto..and I'm running 33"s...It works great on and off road..I even trailer two ATV's around with no issues.

I'm averaging 16-17 mpg..

Does it have a ton of Power...NOPE but it gets the job done.

 

My first Jeep, so no other experience with other Jeep engines , but with that said I like my 3.8 much better with the AEM CAI, Magnaflow exhaust and Superchips programmer - seems to be all I want/need with DD and some weekend wheelin'

 

I have had my Jeep a year now and I am now okay with the 3.8L. I was unimpressed with the performance in the beginning since I was used to a V8. I expect its power output is appropriately matched to the rest of the drive train to prevent parts from breaking.

 

I dont mind the 3.8. I knew it was slow, and thats what I expect. I just look at it as getting from point A to point B. It is faster than walking for sure!

 

A perfect combination for a daily driver / weekend wheeler -- but wait, are you sure they were 3.73's and not 3.21's? I thought the '10 JK 6-speed 2-door came with 3.21's -- originally I thought I had 3.73's but just happened to look at the window sticker which I still had, and it shows 3.21's.

Given how my combination of 32" / 6-speed / 3.21 feels (slightly shy of perfect), I bet 3.73's would really be the sweet spot for this setup.

 

3.73's were a $50 option on the "S" package 2010 JK 6-speed 2-door.