The JK has a 3.8 and the Liberty has a 3.7. I wonder why?

 

This question was asked of a jeep engineer in a q and a session over on jeepforum. There are a number of reasons. The 3.8 is an OHV engine vs OHC for 3.7 - OHV engines generally have better low rpm torque characteristics. The 3.8 was found to replicate the 4.0's power characterisitcs better than any other engine, including the 3.7. The 3.8 is an older, proven, reliable engine, having seen high volume and extended service in the minivans and other chrysler products. The 3.8 is as fuel efficient as the 3.7. There was capacity to build the 3.8 (can't remember if lack of capacity was an issue with the 3.7). The 3.8 is an older, relatively simple design that is easy to work on outside of a shop (such as on the trail). These are all the reasons I can think of that have been mentioned, but I'm sure there are some I'm missing.

 

I would have went for the diesel if it were available:sad:

 

Another key reason is simple economics: They have a bunch laying around and have to use 'em up before the new engine family (i.e. the "Phoenix" line-up) is introduced.

You can find a lot of "why did they do that" answers in the Jeep engineers' Q & A, but don't waste your time visiting that LESSER forum which shall remain unnamed... check out the exhaustive write-up I did a while back... see here).

Hope that helps.

 

Why is that John? I've seen several people mention they'd prefer the CRD. What does the diesel do better than unleaded engines?

I also think a 4.0 V6 would have been nicer...oh well, I think the 3.8 works just fine.

 

Diesels are generally torque monsters and are more efficient on fuel. Biodiesel comes to mind as well.....and with proper maintenance, they'll go 200k plus.
One of my buddies has a Jetta diesel (I know, not much of a comparison to the 3.8) but he knocks down 45-50 mpg on average. That Car has almost paid for itself in fuel savings. I know that the JK could never achieve that with a diesel powerplant, but it would have to be better that the 16-17 I'm getting now.
Oh yeah, and they sound cool

 

Thanks, guys.

 

Just a point of clarification... they could not have used engines that are sitting around as the jeep engine is a north south layout and the minvan is an east west lay out. The cast is different. Also, the JK engine has a beefed up oil pump.