Shoal Creek

I was happy with the 3.8 liter when I first got my JK. I am even happier with it now that it has the intake and catback exhaust upgrades installed.

I think that the engine is like everything else on the JK. If you don't like it, or need more, tougher, stronger, etc..., just upgrade it to the way you want it.

dougr5150

Back on topic here.

Does anyone know the weight of the mini vans that had the 3.8 compared to a JK?

07 RBY

Hey guys, I didn't mean for you to start a pi$$ing contest. I was just asking a simple question. The last two Jeeps I owned, both had 4.0 straight 6's in them. Thanks for all the useful input.

cab76

Here's a little write up I did on a thread where some were complaining about the 3.8's efficiency and gas mileage of JKs in general - did some research and found that the Dodge Caravan AWD is about the same weight as the JK Rubi Unlimited:

First of all, I am very concerned about MPG - it is one of the primary things I look for when purchasing a vehicle, including a Jeep. In fact, one of the reasons I decided not to purchase a TJ Unlimited a couple years ago was the 14/18 epa mpg figures.

With all that said, however, I think Jeep has done a good job choosing an engine that meets all of the JK's needs well, including increased mpg. Jeep definitely was thinking about mpg when it designed the JK, just not so much that it sacrificed the other design objectives for the JK, which I think was exactly the right approch (and so do many others given the brisk sales of the JK so far).

Let me do a quick comparison to illustrate my point. The 2004 Dodge Caravan AWD (2004 was the last year for AWD) has the same engine as the JK (3.8L OHV V6), weighs about 4,400 lbs, and is arguably a much better platform for mpg than the JK. It is lower to the ground, more aerodynamic, runs on lower profile, street oriented tires, etc. It's EPA numbers are 15 mpg city and 21 mpg highway.

Jeep has managed to put the Caravan's engine in the JK and has obtained EPA numbers for the 07 Unlimited Auto of 16 city and 19 highway (note that the JK Unlimited Rubi Auto weighs 4,340 lbs - almost the same as the Grand Caravan AWD). The JK is even better in the city than the Caravan and only a couple mpg worse on the highway! And these numbers have been replicated by many on the forum - some are seeing worse numbers but some are seeing better numbers as well. Remember this is in a vehicle that is much higher off the ground, has much worse aerodynamics, has solid axles, and has relatively high profile all-terrain tires. Amazing!

Jeep has not forgot about mpg in designing the JK. Remember the slightly curved windshield and curved body lines that had purists up in arms a year and a half ago. That certainly wasn't done to improve off-road performance! The plastic air dam underneath - ditto.

And as for choosing the 3.8 - I'm glad they didn't put a more modern, efficient engine in the JK. The 3.8 is a proven, reliable engine that is an OHV design rather than OHC. It is apparantly relatively easy to work on and an OHV design inherently has better low rpm torque characteristics when compared to an OHC design. The 3.8 I would guess is also cheaper than other OHC engines, such as that 4.0 in the Nitro. Jeep managed to sell a comparably equipped JK cheaper than a comparably equipped TJ when it first came out - this is undoubtedly due in part to less expensive engine components - savings that were passed on to consumers (until a mid year price increase thanks to unexpectedly high demand). So, all things considered, including MPG, I think the 3.8 is a great choice for the JK.

I would like to see a diesel added in a couple years as an option for more power and better mpg when 50-state diesel emissions are figured out. But for now I will happily purchase a JK with the 3.8, even with rising gas prices.

cab76

Right...

The title of the thread is: Do we REALLY have minivan engines? As in, I just noticed that our engine is the same size as these minivan engines - Jeep couldn't have been stupid enough to put the same soccer mom engine in a Jeep - could they? OK - I know I'm putting words in your mouth so to speak and some people have gotten way too bent out of shape over your question - but that is the clear tone of your post - it wasn't just a simple question.

You probably haven't been on the JK forums long enough to understand that this has been a point of contention ever since the JK was introduced last year and some people are a little sensitive about this because there are some that actually argue that the 3.8 is not a good engine, just because it also sees duty in the lowly minivan.

07 RBY

I've been here long enough to figure out it's a decent replacement for the 4.0.