From 3.8L to 3.6L, Less Equals More—Way More
Day versus night, black versus white, Wrangler 3.8L versus Pentastar 3.6L. Opposites, but not even in the same league. That is the best way to compare the new 3.6L V-6 engine available in all ’12 Jeep Wranglers to the outgoing larger-displacement minivan 3.8L slug. Hello, Pentastar 3.6L. With 285 hp (up 40 percent) and 260 lb-ft of torque, (up 10 percent), the ’12 Wrangler doesn’t just outdrag the 2011 by car lengths. It’s more like football fields!
We recently attended a media introduction of the new Pentastar engine at beautiful Lake Tahoe, California. The presentation included opportunities to drive 3.8L-equipped ’11 Wranglers back-to-back against ’12 models equipped with the Pentastar 3.6L on the mountainous highways (including Donner Pass at 7,056 feet above sea level) in and around Squaw Valley. Then we were treated to a chance to wheel the ’12 models over the famed Rubicon Trail to check out the new engine’s crawlability in a proper Jeep environment.
The new engine is a follow-up to last year’s upscale interior improvements. Wrangler sales are better than ever, and Chrysler feels that the upgrades on the ’11 (new dash, bigger windows, color-keyed tops and fenders) contributed to the success. A new powertrain for 2012 was the next logical step. Not to worry. Despite them boys messin’ with the original JK, the Jeep engineers and marketing guys “get it.” Under their watch, Wranglers will always have live axles for unparalleled off-road performance, removable doors and tops, hose-out interiors, and the like—all the traits that make a Jeep a Jeep. But for 2012, the JK can now get out of its own way, and do it in snazzy new colors and with better driver comfort.
So how is that new engine? The Pentastar V-6 first appeared in the Jeep Grand Cherokee last year. It is 90 pounds lighter than the old 3.8L due to its all-aluminum construction and integrated exhaust manifolds. Although it is a 60-degree V-6 and shorter than the old 3.8L, it looks bigger under the Wrangler’s hood due to its dual overhead cam heads. We found the underhood area to be much more “filled” than last year.
Another observation is noise, or lack thereof. The Pentastar is quiet and has a willingness to rev. Its redline is 1,100 rpm higher than the 3.8’s (6,600 versus 5,500), but from the sound you’d think it wasn’t even breathing hard. The poor old 3.8L is screaming at five grand—where it always seems to be—while the lack of noise from the Pentastar at six grand makes you wonder if the tach is even working.
As for seat-of-the-pants driving, there is no comparison. With the 3.8L you mash the gas constantly and wait for something to happen. However, the 3.6L moves out smartly in any situation, from stoplights to passing rigs at 65 mph. It’s no Hemi, but it allows the JK (especially the heavier four-door with an automatic) to feel like a modern vehicle now and hang with modern traffic.
Speaking of automatics, the slushbox is new for 2012 too. Now found behind the Pentastar is the five-speed A580, which is installed in other Chrysler vehicles behind the 5.7L Hemi, so it should prove plenty stout in the Wrangler. The extra gear allows the new Wrangler to achieve 21 mpg on the highway, something the hard-working 3.8L could never match. The A580 also has a lower First gear than the previous transmission, which provides a lower overall crawl ratio when wheeling. The only feature that scares us is the “filled for life” tranny fluid and lack of a dipstick to check for water contamination or burnt fluid, two common occurrences when you’re wheeling an automatic.
For those of us who still prefer to shift when we want, the NSG six-speed manual is carried over unchanged. As good as the new automatic is, our favorite for off-idle crawling over the Rubicon in First or Second gear was the stick. Jeep has perfected the drive-by-wire throttle to the point where it feels like the real thing. Wheeling either transmission option on the trail was a piece of cake.
We’ve mostly waxed prolific about the ’12 Wrangler’s on-road behavior, but how is it off road? Well, the new engine is all about helping the JK on the highway. Fortunately, it gives up nothing off-road. The 3.8L was competent in the dirt, and the new 3.6L is every bit its equal, but with even better throttle control. The modern JK with the Rubicon package is a fantastic wheeler right out of the box. It’s the kind of rig many of us have strived to build with a mishmash of parts in our garages for years. Now you can just trot down to your local Jeep dealer and drive off the lot Rubicon-ready. And now you’ll have a lot of fun at that first traffic light!