I was looking for some feedback from Bitog members who have driven the new 3.6L Pentastar engine. Thanks!
Anyone driving a Pentastar GC or Wrangler?
- Thread starter demarpaint
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My folks took delivery of their 2012 Rubicon Unlimited last week, and really like it. It's replacing a 2006 TJ. Dad said it feels a lot like their old Acura (which we bought last year). It's smooth and powerful, and rather quiet at speed. They'll be here in October, so I could give you first-hand feedback then.
I'm curious also. Its got big horsepower numbers, but I've read comments that the torque curve is a good bit "peakier" than the old 3.5 and 4.0 v6. Looks like it really needs a 6-speed (or more) transmission. I don't really doubt that it will be well-engineered and reliable- ALL Chrysler engines with the exception of the 2.7 have been bulletproof for the last, oh, 90 years ;-) Engines have never been Chrysler's problem.
That said, I am a little skeptical of the cast-in-head exhaust manifolds. Not so much because it prevents modification (modern engines are so optimized that most things like headers are not very effective anyway) but it seems like it might transfer a lot of unnecessary heat to the cooling system, a lot like the way old flathead Ford v8s did by running long exhaust passages through the block.
That said, I am a little skeptical of the cast-in-head exhaust manifolds. Not so much because it prevents modification (modern engines are so optimized that most things like headers are not very effective anyway) but it seems like it might transfer a lot of unnecessary heat to the cooling system, a lot like the way old flathead Ford v8s did by running long exhaust passages through the block.
The cast-in exhaust collectors are becoming more common. Honda has used them on most of its J-series V-6 engines (first introduced on the J30A4 in 2003), and then again in some of its I-4 engines (such as the K24 beginning with the K24Z4). It saves weight over the use of an external header, is more compact (which I imagine is helpful when squeezing an OHC V-6 longitudinally into a Wrangler), and offers the potential for better emissions performance, if the catalytic converter is bolted right to the cylinder head (as it typically is when this design strategy is used).
To be fair, Honda's V-6 engines are noted to run high cylinder head temperatures. I do think, though, that this could be overcome with a cooling system designed with this in mind from the beginning, as it appears to have been in Chrysler's case.
I am very interested in the performance of this engine. I was disappointed in the 3.6's performance in Car & Driver's minivan review a few months ago. Despite packing the best power-to-weight ratio of all the vans tested (Chrysler T&C, Honda Odyssey, Nissan Quest, Toyota Sienna), the Chrysler posted only the third-best 0-60 time. It may be true that the torque curve of this engine is peakier than one might like to see in larger vehicle applications. The 6.7 second 0-60 time that Motor Trend posted with a new Wrangler, however, impresses. It even leads me to scratch my head on that middling 0-60 performance of the van with the same engine.
To be fair, Honda's V-6 engines are noted to run high cylinder head temperatures. I do think, though, that this could be overcome with a cooling system designed with this in mind from the beginning, as it appears to have been in Chrysler's case.
I am very interested in the performance of this engine. I was disappointed in the 3.6's performance in Car & Driver's minivan review a few months ago. Despite packing the best power-to-weight ratio of all the vans tested (Chrysler T&C, Honda Odyssey, Nissan Quest, Toyota Sienna), the Chrysler posted only the third-best 0-60 time. It may be true that the torque curve of this engine is peakier than one might like to see in larger vehicle applications. The 6.7 second 0-60 time that Motor Trend posted with a new Wrangler, however, impresses. It even leads me to scratch my head on that middling 0-60 performance of the van with the same engine.
Sure sounds smooooooth.
Nice ride Hokie! Wish them luck. Did they get the WA580 automatic tranny? I heard that its leaps and boungs better than the 4 speed used up until 2011.
I was planning on ordering a 2012 Wrangler, but things are a little tighter $$ wise than I was hoping. Do you guys think they'll keep the Pentastar w/o DI and use the WA580 in the 2013 model year? I got the impression from reading at the All Par site that the 3.6 might stay DI free for another year or so. I think DI is a problem in search of a solution, and all I need is another year. JMO
I was planning on ordering a 2012 Wrangler, but things are a little tighter $$ wise than I was hoping. Do you guys think they'll keep the Pentastar w/o DI and use the WA580 in the 2013 model year? I got the impression from reading at the All Par site that the 3.6 might stay DI free for another year or so. I think DI is a problem in search of a solution, and all I need is another year. JMO
Yes, they got the automatic. All they do with it is rock crawling, and it's nearly impossible to do real rock crawling with a manual. Their '06 is an automatic also. The '06 is weighed down with all sorts of mods and equipment (long arms, tummy tuck, rock sliders on everything, 10k# winch, 37s, big brakes, etc). Much to my surprise (honestly), they haven't had any transmission problems with the '06. I thought for sure that poor little 42RLE would have given them problems by now with all that weight. I was encouraging them to put a shift kit in it but they never did. The engine sure was overloaded. Typical of the 4.0L, it just took the abuse and kept on going, but it sure doesn't sound happy when it's doing it.
As much as the 3.8L V-6 is despised by old-schoolers, my folks say the JKs just run away from the TJs on the way up to the trails. The 3.6L will obviously be much faster still.
As much as the 3.8L V-6 is despised by old-schoolers, my folks say the JKs just run away from the TJs on the way up to the trails. The 3.6L will obviously be much faster still.
Good info! Now if I can figure out if the WA580 will remain for 2013 and not get replaced with a 6 speed AT, and the engine remain DI free for 1 more year I'm golden! I have a feeling 2014 is going to be a year of major changes, not 2013, but then again who knows......
My dad knows some guys at AEV, and I guess those guys are tied in close to Jeep. The word is the 5-speed is here to stay, at least for the near future. They know of no plans to put a 6-speed automatic in the Wrangler. Of course anything can change.
I do agree with you on direct injection. I'm not comfortable enough with its cost-to-benefit ratio yet to buy anything with it.
I do agree with you on direct injection. I'm not comfortable enough with its cost-to-benefit ratio yet to buy anything with it.
Originally Posted By: Hokiefyd
My dad knows some guys at AEV, and I guess those guys are tied in close to Jeep. The word is the 5-speed is here to stay, at least for the near future. They know of no plans to put a 6-speed automatic in the Wrangler. Of course anything can change.
I do agree with you on direct injection. I'm not comfortable enough with its cost-to-benefit ratio yet to buy anything with it.
The news on the 5 speed is good! Thanks! If you find anything out about the Pentastar 3.6 becoming DI for 2013 please let me know. If that's the case I'll wait till after Jan 1, bite the bullet and get the 2012. As much as waiting is better for me at this time I'd rather not get stuck with DI if I can avoid it.
My dad knows some guys at AEV, and I guess those guys are tied in close to Jeep. The word is the 5-speed is here to stay, at least for the near future. They know of no plans to put a 6-speed automatic in the Wrangler. Of course anything can change.
I do agree with you on direct injection. I'm not comfortable enough with its cost-to-benefit ratio yet to buy anything with it.
The news on the 5 speed is good! Thanks! If you find anything out about the Pentastar 3.6 becoming DI for 2013 please let me know. If that's the case I'll wait till after Jan 1, bite the bullet and get the 2012. As much as waiting is better for me at this time I'd rather not get stuck with DI if I can avoid it.
The 5 speed may be durable but it is so widely and tall spaced that it sucks for acceleration. Check out the grand Cherokee 0 to 60 3.6 and you'll see what I mean. It shifts once to get to sixty, most six speeds shifts 3, 4 times to keep of in the powerband. Then again, in a wrangler that wouldn't matter much if at all to most people.
Posted from my HTC Inspire 4G
Posted from my HTC Inspire 4G
Very nice numbers in a Wrangler 2dr:
http://www.motortrend.com/roadtests/suvs/1110_2012_jeep_wrangler_first_test/
TRANSMISSION 6-speed manual
0-60 MPH 6.7 sec
QUARTER MILE 15.2 sec @ 89.1 mph
http://www.motortrend.com/roadtests/suvs/1110_2012_jeep_wrangler_first_test/
TRANSMISSION 6-speed manual
0-60 MPH 6.7 sec
QUARTER MILE 15.2 sec @ 89.1 mph
Originally Posted By: Nick R
The 5 speed may be durable but it is so widely and tall spaced that it sucks for acceleration. Check out the grand Cherokee 0 to 60 3.6 and you'll see what I mean. It shifts once to get to sixty, most six speeds shifts 3, 4 times to keep of in the powerband. Then again, in a wrangler that wouldn't matter much if at all to most people.
Posted from my HTC Inspire 4G
I read the gearing in the 5 speed AT was just right for the Wrangler, especially after the 4 speed AT they used for years. I haven't driven one yet though. I just don't think the 6 speed AT is as stout at the WA580 or Chrysler will get the DI engine right either. The current platform seems perfect for me. Man plans and God laughs, all I need is another year for my comfort level to be a bit higher. LOL
The 5 speed may be durable but it is so widely and tall spaced that it sucks for acceleration. Check out the grand Cherokee 0 to 60 3.6 and you'll see what I mean. It shifts once to get to sixty, most six speeds shifts 3, 4 times to keep of in the powerband. Then again, in a wrangler that wouldn't matter much if at all to most people.
Posted from my HTC Inspire 4G
I read the gearing in the 5 speed AT was just right for the Wrangler, especially after the 4 speed AT they used for years. I haven't driven one yet though. I just don't think the 6 speed AT is as stout at the WA580 or Chrysler will get the DI engine right either. The current platform seems perfect for me. Man plans and God laughs, all I need is another year for my comfort level to be a bit higher. LOL
Originally Posted By: Nick R
The 5 speed may be durable but it is so widely and tall spaced that it sucks for acceleration. Check out the grand Cherokee 0 to 60 3.6 and you'll see what I mean. It shifts once to get to sixty, most six speeds shifts 3, 4 times to keep of in the powerband. Then again, in a wrangler that wouldn't matter much if at all to most people.
Posted from my HTC Inspire 4G
"The" 5-speed? WHICH 5-speed? There are two used in rear-drive Chrysler products. The 545RFE is best geared for trucks with torquey v8s, the WA580 has closer ratios and is much better suited to smaller engines and/or lighter performance-oriented vehicles, which is why its found in the R/T and SRT-8 LX/LC platform cars as well as some Jeeps (I'm not entirely sure which ones get it).
But you're right, the 3.6 probably needs more speeds still, to keep the ratios really close... and fortunately the word is that 5-speeds will be phased out in favor of the new Chrysler/ZF 8-speed. I haven't heard what the plan is for the keeping or replacing 68RFE behind the Cummins, though it looks like there are versions of the 8-speed that might be beefy enough for that application too.
The 5 speed may be durable but it is so widely and tall spaced that it sucks for acceleration. Check out the grand Cherokee 0 to 60 3.6 and you'll see what I mean. It shifts once to get to sixty, most six speeds shifts 3, 4 times to keep of in the powerband. Then again, in a wrangler that wouldn't matter much if at all to most people.
Posted from my HTC Inspire 4G
"The" 5-speed? WHICH 5-speed? There are two used in rear-drive Chrysler products. The 545RFE is best geared for trucks with torquey v8s, the WA580 has closer ratios and is much better suited to smaller engines and/or lighter performance-oriented vehicles, which is why its found in the R/T and SRT-8 LX/LC platform cars as well as some Jeeps (I'm not entirely sure which ones get it).
But you're right, the 3.6 probably needs more speeds still, to keep the ratios really close... and fortunately the word is that 5-speeds will be phased out in favor of the new Chrysler/ZF 8-speed. I haven't heard what the plan is for the keeping or replacing 68RFE behind the Cummins, though it looks like there are versions of the 8-speed that might be beefy enough for that application too.
Originally Posted By: demarpaint
I just don't think the 6 speed AT is as stout at the WA580 or Chrysler will get the DI engine right either.
Just for clarity, the only current Chrysler rear-drive 6-speed is the 68RFE, and its *definitely* much stouter than the WA580. It goes behind the 24-valve Cummins in non-PTO applications. Chassis-cabs with PTOs get a cast-iron case Aisin 6-speed automatic. The minivans use a little front-drive 6-speed transaxle with the 3.6, which does have very nice ratios for that engine.
As for DI... I wouldn't want to be an early adopter, but never bet against Chrysler where engines are concerned, that's always been what they do absolutely best. I could easily see Chrysler being the first to really get DI right.
I just don't think the 6 speed AT is as stout at the WA580 or Chrysler will get the DI engine right either.
Just for clarity, the only current Chrysler rear-drive 6-speed is the 68RFE, and its *definitely* much stouter than the WA580. It goes behind the 24-valve Cummins in non-PTO applications. Chassis-cabs with PTOs get a cast-iron case Aisin 6-speed automatic. The minivans use a little front-drive 6-speed transaxle with the 3.6, which does have very nice ratios for that engine.
As for DI... I wouldn't want to be an early adopter, but never bet against Chrysler where engines are concerned, that's always been what they do absolutely best. I could easily see Chrysler being the first to really get DI right.
Originally Posted By: Hokiefyd
As much as the 3.8L V-6 is despised by old-schoolers, my folks say the JKs just run away from the TJs on the way up to the trails. The 3.6L will obviously be much faster still.
The 3.8 has a torque curve shape almost identical to the old 4.0L inline 6. I certainly don't "hate" it, I agree with the Jeep engineers who picked it as the best possible replacement for the 4.0 at the time. People also forget that its nearly as old and proven a design as the 4.0, too. The 4.0 came out in 84, the 3.8 came out in 90 (and the 3.3 its based on came out in 89).
I also wouldn't bet on the 3.6 being faster up the trails just yet. On-road... absolutely. Up the trails... maybe not, for all the other reasons discussed so far (transmission ratios and number of speeds, peaky torque curve).
As much as the 3.8L V-6 is despised by old-schoolers, my folks say the JKs just run away from the TJs on the way up to the trails. The 3.6L will obviously be much faster still.
The 3.8 has a torque curve shape almost identical to the old 4.0L inline 6. I certainly don't "hate" it, I agree with the Jeep engineers who picked it as the best possible replacement for the 4.0 at the time. People also forget that its nearly as old and proven a design as the 4.0, too. The 4.0 came out in 84, the 3.8 came out in 90 (and the 3.3 its based on came out in 89).
I also wouldn't bet on the 3.6 being faster up the trails just yet. On-road... absolutely. Up the trails... maybe not, for all the other reasons discussed so far (transmission ratios and number of speeds, peaky torque curve).
I'm very familiar with the 3.3/3.8. I've owned two of them and they're very nice little mills. Not the most refined, but very durable and smooth at what they do.
The 3.6L wouldn't necessarily be faster "up the trails". But it's much faster "up TO the trails".
I prefer the wider gear spacing myself. See Nick's posting of that YouTube video of a 62TE in the Journey. It's always shifting and keeps the engine above 5,000 rpm at WOT. Is that absolutely best for acceleration? I'm not so sure. It doesn't have as satisfying of a "pull" in a gear when that gear lasts only 3 seconds at full throttle. I'm of the opinion that 5 forward speeds are usually ideal, but 6 are okay when spaced wide enough. I don't like the "rapid fire" shifting of some 6 speeds.
The 3.6L wouldn't necessarily be faster "up the trails". But it's much faster "up TO the trails".
I prefer the wider gear spacing myself. See Nick's posting of that YouTube video of a 62TE in the Journey. It's always shifting and keeps the engine above 5,000 rpm at WOT. Is that absolutely best for acceleration? I'm not so sure. It doesn't have as satisfying of a "pull" in a gear when that gear lasts only 3 seconds at full throttle. I'm of the opinion that 5 forward speeds are usually ideal, but 6 are okay when spaced wide enough. I don't like the "rapid fire" shifting of some 6 speeds.
I think I can handle 6 speeds, an 8 speed AT, no thanks. For an off road vehicle I think a 5 speed AT is all you need. That's if you like an automatic transmission.
I rented a new GC 4x4 last week and ran a couple tanks through it. I was not impressed with the acceleration, the gearing was very tall overall. I don't know if there are any gearing options. I noticed that both 4th and 5th gears were taller than my 6th. Having driven a charger with the same engine a couple weeks ago, I was expecting more. I was surprised how similar (from memory) the engine sounded and felt compared to the old 4.0 I6 in the mid 90's GC (minus the tapping). Obviously they couldn't be more different. The transmission felt good mostly, but a couple times I floored it on the highway and it took a long time to downshift, other times it downshifted quickly. Both the charger and the GC sounded like there was a bit of an exhaust leak at the head, I guess it is a characteristic of that engine.
I was impressed by the overall quietness and solid feel. Also I averaged just over 20 miles per gallon combined around Atlanta - which is pretty good for me. Brakes felt good, steering felt kind of twitchy at 80, but would probably feel great in the woods or in the city.
Interior was very nice, everything was soft. Tach had a green zone between 900 and 1,750. I did not care for the angled chrome rings around the gauges, but that is subjective.
I was impressed by the overall quietness and solid feel. Also I averaged just over 20 miles per gallon combined around Atlanta - which is pretty good for me. Brakes felt good, steering felt kind of twitchy at 80, but would probably feel great in the woods or in the city.
Interior was very nice, everything was soft. Tach had a green zone between 900 and 1,750. I did not care for the angled chrome rings around the gauges, but that is subjective.
I think they use 3.06 and/or 3.21 gearing in the GC. That would not be very impressive when it comes to acceleration but would help with mpg. I'll be going with 4.10 gearing in the Rubi when I do pull the trigger.
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