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  #13  
Old 07-11-2012, 10:57 PM
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Re: **NEW**4.8 V8 Pentastar based engine for next gen WK(2015-16)?

Some things about the Pentastar would extend easily to a V8 ( pent roof 4-valve head, DOHC, everything alloy and plastic) while others would not (60 degree block, log exhaust manifold.

Yes Virginia, a 60 degree V8 is possible but would need some massive balance shafts. Even so when Buick tried a 90 degree V6 they wound up having to use an offset crank (even-fire) to tame vibration. So possible but would require some interesting design kludges & more weight.

Much less costly would be a stroked 4.2 liter V-6 "square" engine (same 3.78" bore and stroke). Personally was surprised to find a short stroke "oversquare" design for high compression (10.2) and trash gas (87 PON), probably the bore is possible only with the central spark plug and careful modeling of the flame front propagation.

Many Japanese cars have 10+ compression but are also undersquare with small bore limiting the distance from the plug to the edge of the chamber.

Sorry about getting technical but once you understand the design "envelope" you can see where to push it. If you do not understand that octane has nothing to do with power, just flame propagation rate (how fast it burns) then fagedaboudit.
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  #14  
Old 07-12-2012, 06:55 AM
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Re: **NEW**4.8 V8 Pentastar based engine for next gen WK(2015-16)?

lol
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  #15  
Old 07-12-2012, 06:16 PM
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Re: **NEW**4.8 V8 Pentastar based engine for next gen WK(2015-16)?

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Originally Posted by Scottina06 View Post
Lol.....how do u even know before anything is released? A higher HP modern engine that gets better fuel economy than the antiquated hemi is seriously what Chrysler needs to keep up with the competition.
I've driven the Pentastar, and didn't care for it that much. It wasn't as stout feeling as the Duratec 35 and 37 Ford uses, despite having more power than many of those variants.

Unfortunately, I suspect you're right, because at the end of the day modern consumers demand high peak hp numbers, with little regard to useful power, or power curves.

Truth be told, I'd be more interested in a stroked 4L version of the Pentastar with some small turbos like the Ecoboost has than a Pentastar derived V8. And frankly, I think that's where the future is, not in something along these lines.

FWIW, I want torque. 400hp is great and all, but if it doesn't have low end torque to back it up, it's just not going to be an engine I will enjoy driving around. My previous vehicle was powered by Honda's J35 engine with 250hp. Unfortunately, it was designed so that most of that power was only after about 4200rpm, and if you were trying to just cruise around town casually, it was downshifting and in many cases would have to drop so it was spinning around 3500rpm (which was loud and obnoxious).

I'll take lower hp and plenty of torque every day over peak hp numbers marketing.
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Old 07-12-2012, 09:08 PM
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Re: **NEW**4.8 V8 Pentastar based engine for next gen WK(2015-16)?

Now you are talking turbo diesel.
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  #17  
Old 07-13-2012, 08:08 PM
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Re: **NEW**4.8 V8 Pentastar based engine for next gen WK(2015-16)?

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Now you are talking turbo diesel.
Yep. I said last time my next vehicle would likely be a TDI, but the cost/fuel didn't work out for me this go around compared to a v8.
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  #18  
Old 07-17-2012, 01:36 PM
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Re: **NEW**4.8 V8 Pentastar based engine for next gen WK(2015-16)?

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Originally Posted by Scottina06 View Post
Looks like Chrysler is working on a NEW 4.7--4.8 V8 based on the Pentastar engines we have now. These will DEFINETELY be used on the Grand Cherokee for 2016 if everything comes to fruition. Expect much better fuel economy from the new V8 and more HP/TQ than the current 5.7 hemi. Looks like the next gen WK GRand Cherokee is gonna be epic!
Good to know! I expected no further V8s to come after the WK2 with turbo'd V6s being the future
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Old 07-23-2012, 10:47 AM
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Re: **NEW**4.8 V8 Pentastar based engine for next gen WK(2015-16)?

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Originally Posted by FAUEE View Post
I have no desire to have a Pentastar based V8. It just doesn't have the low end grunt that an old school V6 or V8 has. Sure it may have better peak hp numbers, better fuel efficiency numbers, but that's at the expense of driveability.

GM's V6 now is a prime example. Never has 300hp felt so gutless and strained to move a vehicle.

Torquey power is where it's at, and I'm concerned that an engine such as this wouldn't have the low end grunt I like about the Hemi. I could have bought a lot of other vehicles, but I liked that the Hemi had that low end grunt I wanted. If I didn't care about that, there's a lot of V6s out there which could have worked just as well.

The 4.7L in 08+ ws a "mini Hemi" and it didn't work. Price difference wise, people will just buy the Hemi.
I don't know but I've been lovin' the 4.7L V8 in my 2000 WJ for a dozen years now!
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Old 09-21-2012, 09:56 PM
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Re: **NEW**4.8 V8 Pentastar based engine for next gen WK(2015-16)?

Any more recent info on this new V8?
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Old 09-22-2012, 02:13 AM
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Re: **NEW**4.8 V8 Pentastar based engine for next gen WK(2015-16)?

Dohc engines and pushrods ones have been around forever. The hemi is not antiquated. DOHC are more efficient but a Hemi can pack more power into a smaller space. DOHC engines are very tall. For example a common conversion is putting a corvette engine in a Miata. It's not great on gas but it fits in that small engine bay.

I'd take a high displacement pushrods over a equal sized dohc when gas is cheap .
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  #22  
Old 09-22-2012, 09:53 PM
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Re: **NEW**4.8 V8 Pentastar based engine for next gen WK(2015-16)?

I have both the Pentastar and the Hemi (the firstone on my WK2 and the Hemi on the 2005 Durango) and I would have the Hemi everytime. I recon I like the tranny on the Durango better than the one in the WK2, but the feel of the Hemi is everything. I din't get a Hemi WK2 only because I didn't had the money for it, I hope I can get one in a year or 2. However I would try it first, because I've tested a 2008 Hemi WK and it didn't feel the same as in the Durango, I think it's because of the active MDS, which the Durango does not have (and I get pretty decent fuel economy on 87 gas).
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  #23  
Old 09-26-2012, 04:39 PM
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Re: **NEW**4.8 V8 Pentastar based engine for next gen WK(2015-16)?

Quote:
Originally Posted by JTS97Z28 View Post
Lol it never ends. Now people dying to order a 2014 are gonna see this and want to wait for a 2015. Best thing to do is take delivery of your Jeep and never visit JG.org haha

LOL! Amen to that. My next Jeep will have a 4.8L Pentastar V8.
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  #24  
Old 09-30-2012, 08:45 AM
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Re: **NEW**4.8 V8 Pentastar based engine for next gen WK(2015-16)?

I think this interesting talk.... :-)
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