HEMI swap for the JL?

Spank

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This conversation is very interesting and very baffling to me. I am having a hard time understanding, when there have been millions of wranglers on the road, who have been able to push through the wind, how someone could justify as sensible spending $20-$30k to swap out an engine because in part they are worried about their wrangler fighting through the wind, or towing.. People are always breaking Aventus's balls about how he is looking for the wrong car with his "high end" wants, but it sounds like the people who want to make this swap are trying to turn their wrangler's into sports cars, or pick up trucks, and that is not what they are designed to be. Feel free to try to enlighten me if you want, but this was more of a rhetorical question because I am baffled. Then again, I am willing to spend $5-6k to improve my stereo system in my jeep, so maybe I am just as nuts but in a different way.
I agree. I've never felt the Wrangler needed a Hemi. The Pentastar's nearly 300HP is plenty. However, it certainly wouldn't hurt to have a smidge more torque in a vehicle designed to crawl and climb. The diesel always made more sense.





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Vegas_Sirk

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This conversation is very interesting and very baffling to me. I am having a hard time understanding, when there have been millions of wranglers on the road, who have been able to push through the wind, how someone could justify as sensible spending $20-$30k to swap out an engine because in part they are worried about their wrangler fighting through the wind, or towing.. People are always breaking Aventus's balls about how he is looking for the wrong car with his "high end" wants, but it sounds like the people who want to make this swap are trying to turn their wrangler's into sports cars, or pick up trucks, and that is not what they are designed to be. Feel free to try to enlighten me if you want, but this was more of a rhetorical question because I am baffled. Then again, I am willing to spend $5-6k to improve my stereo system in my jeep, so maybe I am just as nuts but in a different way.
Just like lots of things in life there may not be a NEED but there is usually a WANT. For example who needs a 707HP Grand Cherokee? Yet FCA is building one.
 

The Great Grape Ape

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I have never actually considered the 5.7L HEMI up until your comment...The 5.7L sounds like it would do the job JUST FINE.
However remember, that's the recent "Eagle" Gen2 and Gen3/2.1 refresh, the earlier 5.7s of a decade ago not only had less HP (which is less important, but 40+HP is still not something to ignore) , but more importantly was also very noticeably much slower at delivering it's torque. So if you find a donor engine make sure it's a recent one 2009+ or more recent to be sure (there were some 2007 applications like RAM but it's also a heavier build).
From 2016 they offered a few crate options with a bunch of configuations, but even the new base one gets you to near 400HP and over 400lbft, and relative to the entire conversion, just a few more sheckles can get you over 400/400 and a bit of weight saving. However it's not as impressive as their top performance models which are awesome light & powerful.. but... also very fragile which Mopar doesn't warranty for anything as their life expectancy is measure in hundreds of miles not thousands.

And you're right: I did not add the need for a comparable and adequate transmission into the mix. But that is because most places out here that have quoted me $30k for the HEMI swap already include a transmission compatible with the 6.4L (or so I've been told).
It also depends on the conversion, the manual transmission in the JK can barely handle the pentastar, so regardless of Hemi it's gotta go, the NAG1 is a robust transmission and has been show to be stronger than its 580NM rating, but Imwould only feel secure with it on the 5.7 and an older and weaker 6.1 or a heavy truck 6.4 which is tuned for fuel economy, durability and low end torque which crest just at the max of the NAG1, and while those characteristics seem to make it a perfect fit, it's much heavier than the 5.7, and compared to a Gen2 slmost side by side on torque and HP.

A 2012+ JK auto transmission (NAG1) would be fine for all that, and likely even OK for a mild mannered 6.4 (2011-2015) , but if you are going to be going the 392 route then for most conversion they likely think you're not going to be babying it, so might as well swap that too.
Unfortunately there isn't as much headroom on the new transmissions, so even a 5.7 is risking it without a transmission uograde, which means a bit more money to the already high conversion cost.

Finally, maybe a sprintex supercharger would do the trick... or maybe just suck it up and stay with the stock diesel option. However, I just cannot for the life of me see the benefit over the nuisance of the ESS engine. We might as well be driving Prius' at this point... because we all know the ESS engine is only for compliance issues and does next to nothing for fuel economy.
Yeah, like I said, unfortunately desel doesn't work for my use case where remote cold makes it a non-starter... literally.

It will be interesting to see what the after-market options are for 'improving' the upgraded Pentastar, and also how next year's BSG Pentastar fits in with those options. I still likely won't go the mod route until year 3 of the JL when deciding on extended warranty (I like a warrantied daily driver), doing a mod/swap or a new JL is the route, and that will likely be a 2021/2022 JL byt that time, and maybe there's a new Hybrid in the future to make it a more interesting decision process justifying an extra year warranty/ownership, etc.

Still just want a factory Gen2+ 5.7L Hemi, and then I could buy a JL to last me a decade and be done with it.
That would be worth ~$10K to the sticker to me without blinking.
 

The Great Grape Ape

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This conversation is very interesting and very baffling to me. I am having a hard time understanding, when there have been millions of wranglers on the road, who have been able to push through the wind
Have they? Truly pushed through the wind, or have they just gone up against their own air resistance and claimed it was pushing theough the wind because of the common phrase? :whatsgoingon:

I travel both in the mountains and the foothills & prairies where strong sustained winds are not uncommon. Even a mild headwind at 60kmh will cause the Wrangler to want to jump from 2,000 RPM to 3,250+ just to keep the 110Kph speed limit, increase those winds, or the Speed limit to 90/120 and then the engine wants to head even higher to maintain speed with the other vehicles on the highway, and not impede traffic. Having more tq/hp at lower RPMs means that the engine can more easily push against the wind and its own resistance without getting overly excited and cratering fuel economy, and getting hot and stressed. Twice this past summer when crossing NewFoundland highlands and Saskatchewan plains I faced nearly 100Kph headwinds which meant I was going about 7 Kph under the speed limit (on rather empy highways thankfully) in order to keep my RPMs nearer 3,000, yet even then my fuel economy dropped from 12.4L/100KM (19MPG) to 16.5+L /16.8 in Sask (~14MPG) and the brief period that I did the speed limit the Pentastar wanted to stay above 4,000 RPM and crated fuel economy to 22+ L/100KM (~10-11MPG) and neither of those are desirable. Even my old Caravan (aka Ski Bus) in the early 2000s with ttheir s 3.3L engine wasn't anywhere near as affect by the strong winds of the foothills heading to Banff/Louise/Revey as the Wrangler, but moving to the 3.8 with it was definitely more relaxed. Lowering the top or removing the doors just makes it even tougher still.

Having a slight bit more potency would help those of us who truly are pushing our Wrangler bricks into actual strong Winds. :tumbleweed:

It also helps going up hill even when not towing, especially in mountain passes in the Rockies, where the speed limit is wishful thinking in a Wrangler (some times I'm cruising for minutes @ 2/3rds the speed limit because I am already at 3,500 RPM going up hill and don't want to go 5,000+ just to crest one of many ridges/climbs). In that situation altitude is also working against you robing you of power ever foot you climb. Having more to start with is nice, and forced air can help there too, but usually with other associated costs.

how someone could justify as sensible spending $20-$30k to swap out an engine because in part they are worried about their wrangler fighting through the wind, or towing..
As it's their money, probably the same way Americans justify many things, like $5K stereos... while the children of the world starve, etc... :crying:

Of course we could all drive econoboxes so we don't have to justify ourselves, that's typical of people who only buy vehicles based on MPG and resale value and cost of ownership (OK Wrangler does do well in 2 out of 3 of those), they have no passion for their vehicle, it's just a functional tool, but where's the fun in that? If anything a Wrangler is about fun and enjoying your vehicle more than just the 'logical' choices.

However some of us don't want to spend that $20K+ we would prefer that Jeep do for it's halo and often top seeling vehicle, the same as it did for its GC which has a $2K Hemi option (plus a second Hemi option, and a third) and has for years, including the completely unnecessary except for bragging right SRT and TrackHawk variants. For the Wrangler it does make sense, and without the stock option people are forced to give more of their money to third parties, to do what Jeep should've been doing for years and profiting from.

People are always breaking Aventus's balls about how he is looking for the wrong car with his "high end" wants, but it sounds like the people who want to make this swap are trying to turn their wrangler's into sports cars, or pick up trucks, and that is not what they are designed to be.
Really the Wrangler/CJ was never designed as such? Had a V8 in a 2,500lb vehicle in the 70/80s after the fuel crisis in a time when speed limits were 55 not 75? Not designed for off-roading and moving big tires? HMmm sounds like it was designed just for that very thing, but that EPA got in the way of giving it what it needs for those who use it for more than a grocery getter.
I have supported Aventus usually in his quest, and have on the rare occasion busted his balls publically (which got more of a reaction from y'all than him) when it meant changing the Wrangler from a Wrangler to precisely something else where it's best to just make that something else because there will also be enough demand for it to exist too alongside the Wrangler.

The Wrangler is a platform that you can then change to match your needs, so adding bigger rims with low profile tyres means nothing to me, because your use-case doesn't affect mine, so enjoy it as you like. However asking for a stock add-on that makes it into pointless vehicles like a Commander versus offering it as an option on a vehicle it is well suited for, and sells enough to justify it's application, doesn't seem counter to the brand or purpose of a Wrangler; and unlike many of the requests from folks (including Aventus) adding a Hemi as an option has zero impact on the Wrangler's configuration for other users.

I have no desire for a diesel, and likely never will since it can't meet my needs in the cold, however I always supported the Wrangler getting one because I can see how others would use it for their needs, which may mirror some of my own, and it is a good match for off-roading and the light towing duties (especially in the mountains) so more power to them. Sure I don't see the positioning of the tinyturbo4 when it's right next to the Pentastar and doesn't provide much added MPG compared to a naturally aspirated 4, but whatever, I know why it's there.
And while I support those options I'm not trying to displace them of or paint an unrealistic picture of the Hemi in order to make it look more appealing than it is, it IS Heavy, it's NOT the most fuel efficient, but it IS a GOOD fit for the Wrangler for people who do the classic things with a wrangler, like going where there are no roads and towing a small piece of artillery. :captain:

Feel free to try to enlighten me if you want, but this was more of a rhetorical question because I am baffled.
More torque improves off-roading capabilities, and helps get bigger tires of both the crawlers and the posers moving better/quicker, it also helps with people who want to take their seadoo, boat, small or poo-up camper with them when they want to leave the pavement or just do it on paved roads with the roof down/off.

HP for some like me, is a function of what it does for the Wrangler more than who it impresses.

I want both because I litterally do climb mountains in my Wrangler while carrying gear to setup Int'l ski races in the fall to winter, or to access remote backcountry skiing/hiking/picnicking spots, or for multi-day & multi-thousand km/mile treks, and for all that it would be the perfect addition to what is nearly the perfect tool for the job. :jk:

Unlike some people who want the Wrangler to be somthing else, I want it to be more of what it truly IS, and a Hemi would help accomplish that more than the diesel or tinyturbo4.

After ALL THAT... I hope, as requested, that that helps to enlighten/inform you about why it's not trying to make the Wrangler into something else, like a stoplight/0-60 Champ, or a 5th Wheel King of the Road, or a Euro Extreme HP SUV, or a Monster Hill climbing King of the Hammers... just a better Wrangler doing Wrangler things.

However, as much as I know it's the perfect match, I also know that IT WILL likely NEVER HAPPEN in a stock Wrangler from FCA because of the bigger picture concerns like CAFE etc, which is as Sad as it is True. :(

*edited to clean up quotes to avoid what happened to Now&Then's reply, because I accidentally left a spare closed quote.
 
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The Great Grape Ape

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The diesel always made more sense.
Both can be put to good use in a Wrangler for different needs and focuses, it shouldn't have been an either/or situation, and should've mirrored the Grand Cherokee options long ago if it weren't for size/space issues (for the Ecodiesel).

Of course the diesel is heavier, costlier, and makes significantly less HP than not only the Hemi, but even the current Pentastar.

However, neither are outliers, both seem like very good options for the Wrangler, for different uses.
 

nowandthen

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However some of us don't want to spend that $20K+ we would prefer that Jeep do for it's halo and often top seeling vehicle, the same as it did for its GC which has a $2K Hemi option (plus a second Hemi option, and a third) and has for years, including the completely unnecessary except for bragging right SRT and TrackHawk variants. For the Wrangler it does make sense, and without the stock option people are forced to give more of their money to third parties, to do what Jeep should've been doing for years and profiting from.
[/QUOTE]
An impressive reply, but this stood out for me. Well said!
 

chuck h

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Have they? Truly pushed through the wind, or have they just gone up against their own air resistance and claimed it was pushing theough the wind because of the common phrase? :whatsgoingon:

I travel both in the mountains and the foothills & prairies where strong sustained winds are not uncommon. Even a mild headwind at 60kmh will cause the Wrangler to want to jump from 2,000 RPM to 3,250+ just to keep the 110Kph speed limit, increase those winds, or the Speed limit to 90/120 and then the engine wants to head even higher to maintain speed with the other vehicles on the highway, and not impede traffic. Having more tq/hp at lower RPMs means that the engine can more easily push against the wind and its own resistance without getting overly excited and cratering fuel economy, and getting hot and stressed. Twice this past summer when crossing NewFoundland highlands and Saskatchewan plains I faced nearly 100Kph headwinds which meant I was going about 7 Kph under the speed limit (on rather empy highways thankfully) in order to keep my RPMs nearer 3,000, yet even then my fuel economy dropped from 12.4L/100KM (19MPG) to 16.5+L /16.8 in Sask (~14MPG) and the brief period that I did the speed limit the Pentastar wanted to stay above 4,000 RPM and crated fuel economy to 22+ L/100KM (~10-11MPG) and neither of those are desirable. Even my old Caravan (aka Ski Bus) in the early 2000s with ttheir s 3.3L engine wasn't anywhere near as affect by the strong winds of the foothills heading to Banff/Louise/Revey as the Wrangler, but moving to the 3.8 with it was definitely more relaxed. Lowering the top or removing the doors just makes it even tougher still.

Having a slight bit more potency would help those of us who truly are pushing our Wrangler bricks into actual strong Winds. :tumbleweed:

It also helps going up hill even when not towing, especially in mountain passes in the Rockies, where the speed limit is wishful thinking in a Wrangler (some times I'm cruising for minutes @ 2/3rds the speed limit because I am already at 3,500 RPM going up hill and don't want to go 5,000+ just to crest one of many ridges/climbs). In that situation altitude is also working against you robing you of power ever foot you climb. Having more to start with is nice, and forced air can help there too, but usually with other associated costs.



As it's their money, probably the same way Americans justify many things, like $5K stereos... while the children of the world starve, etc... :crying:

Of course we could all drive econoboxes so we don't have to justify ourselves, that's typical of people who only buy vehicles based on MPG and resale value and cost of ownership (OK Wrangler does do well in 2 out of 3 of those), they have no passion for their vehicle, it's just a functional tool, but where's the fun in that? If anything a Wrangler is about fun and enjoying your vehicle more than just the 'logical' choices.

However some of us don't want to spend that $20K+ we would prefer that Jeep do for it's halo and often top seeling vehicle, the same as it did for its GC which has a $2K Hemi option (plus a second Hemi option, and a third) and has for years, including the completely unnecessary except for bragging right SRT and TrackHawk variants. For the Wrangler it does make sense, and without the stock option people are forced to give more of their money to third parties, to do what Jeep should've been doing for years and profiting from.



Really the Wrangler/CJ was never designed as such? Had a V8 in a 2,500lb vehicle in the 70/80s after the fuel crisis in a time when speed limits were 55 not 75? Not designed for off-roading and moving big tires? HMmm sounds like it was designed just for that very thing, but that EPA got in the way of giving it what it needs for those who use it for more than a grocery getter.
I have supported Aventus usually in his quest, and have on the rare occasion busted his balls publically (which got more of a reaction from y'all than him) when it meant changing the Wrangler from a Wrangler to precisely something else where it's best to just make that something else because there will also be enough demand for it to exist too alongside the Wrangler.

The Wrangler is a platform that you can then change to match your needs, so adding bigger rims with low profile tyres means nothing to me, because your use-case doesn't affect mine, so enjoy it as you like. However asking for a stock add-on that makes it into pointless vehicles like a Commander versus offering it as an option on a vehicle it is well suited for, and sells enough to justify it's application, doesn't seem counter to the brand or purpose of a Wrangler; and unlike many of the requests from folks (including Aventus) adding a Hemi as an option has zero impact on the Wrangler's configuration for other users.

I have no desire for a diesel, and likely never will since it can't meet my needs in the cold, however I always supported the Wrangler getting one because I can see how others would use it for their needs, which may mirror some of my own, and it is a good match for off-roading and the light towing duties (especially in the mountains) so more power to them. Sure I don't see the positioning of the tinyturbo4 when it's right next to the Pentastar and doesn't provide much added MPG compared to a naturally aspirated 4, but whatever, I know why it's there.
And while I support those options I'm not trying to displace them of or paint an unrealistic picture of the Hemi in order to make it look more appealing than it is, it IS Heavy, it's NOT the most fuel efficient, but it IS a GOOD fit for the Wrangler for people who do the classic things with a wrangler, like going where there are no roads and towing a small piece of artillery. :captain:



More torque improves off-roading capabilities, and helps get bigger tires of both the crawlers and the posers moving better/quicker, it also helps with people who want to take their seadoo, boat, small or poo-up camper with them when they want to leave the pavement or just do it on paved roads with the roof down/off.

HP for some like me, is a function of what it does for the Wrangler more than who it impresses.

I want both because I litterally do climb mountains in my Wrangler while carrying gear to setup Int'l ski races in the fall to winter, or to access remote backcountry skiing/hiking/picnicking spots, or for multi-day & multi-thousand km/mile treks, and for all that it would be the perfect addition to what is nearly the perfect tool for the job. :jk:

Unlike some people who want the Wrangler to be somthing else, I want it to be more of what it truly IS, and a Hemi would help accomplish that more than the diesel or tinyturbo4.

After ALL THAT... I hope, as requested, that that helps to enlighten/inform you about why it's not trying to make the Wrangler into something else, like a stoplight/0-60 Champ, or a 5th Wheel King of the Road, or a Euro Extreme HP SUV, or a Monster Hill climbing King of the Hammers... just a better Wrangler doing Wrangler things.

However, as much as I know it's the perfect match, I also know that IT WILL likely NEVER HAPPEN in a stock Wrangler from FCA because of the bigger picture concerns like CAFE etc, which is as Sad as it is True. :(

*edited to clean up quotes to avoid what happened to Now&Then's reply, because I accidentally left a spare closed quote.
No one can ever say you are not thorough my friend!!!! Man, I ain't even gonna try to reply other than to say that, because where the heck would I start! Haha. I hope you actually know how to type, if u r a "hunt and peck" typer, or did that all on a phone, u r gonna need to sleep for a week to recover from that response.

And if my question seemed critical, far from it, as u stated, and I 100% agree, part of the beauty of car ownership, when done right, is loving your car, so if someone wants to spend $20k-$50k for an engine swap, God bless ya, go right on ahead, awesome u have the money to do that. I guess I was just thinking it is already the most capable off road vehicle around, as best I know, so the $20k to me seemed overkill, but all good
 

The Great Grape Ape

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LoL, no I wasn't thinking you were being too critical, just thinking there are some common misconceptions of why anyone would want a Hemi, so I thought I'll explain (thoroughly) my desire for that option since you asked, and it seemed like a good idea/thing to add to the thread.

Also, I'm not a hunt & peck..er , been typing on PCs since the 70s, used to be a relay operator for deaf & hard of hearing in college. GA to SK.

Only thing is it's hard to avoid typos on 'slow to keep up' tablets mostly while multi-tasking watching the tube on the couch, or in bored... err... boardrooms/conf-calls at work, especially when pretending to pay attention to a colleague or girlfriend while typing. ;)
 

Spank

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Of course the diesel is heavier, costlier, and makes significantly less HP than not only the Hemi, but even the current Pentastar.

However, neither are outliers, both seem like very good options for the Wrangler, for different uses.
I'd gladly trade 50hp for an added 200lb/ft of torque, but I agree. The fact that buyers will now have an option is ultimately what Wrangler has been missing for a long time.
 

guarnibl

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$50K, WOW! I can't imagine that. Maybe if you order every possible option. (Edit: A well equipped JLUR with the diesel engine will likely get you there).

Window sticker on my 2014 JKUR, manual transmission $39,110. And I paid less than that. Less than $40K out the door (tax, license, title) I ordered it. I am patient and get exactly what I want and nothing more. :)

Base price $34,995
Connectivity group $495
Tow package $395
Supplemental front seat-mounted side airbags $495
A/C with automatic temperature control $395
Freedom top black 3 piece hardtop $995

No automatic.
I put in an aftermarket radio so I didn't buy the upgraded factory NAV system.

Additions this time around:
Automatic ~$1200?
I would like to have blind spot detection. Don't know what that will cost.
Remote start (I think this is around $395 on the JK)
May go with the factory 8" entertainment system, due to all the "built ins" (e.g. rear camera). No interest in factory NAV but will take it if I have to. I will never pay the outrageous price to update it. I'll use my Garmin or my phone. That could add maybe $1200?

I think I am still well under $50K for a very well optioned JLUR. Admittedly not inexpensive, but I have to believe it is at or under $45K sticker.

I can't image going from $39,100 sticker to over $50,000 sticker in just 4 years even when I add in the extras listed above.
Back up camera is federally mandated 2018.5 MY, so you can go with the base radio and still have the backup camera.

RE: base price increase of $2500, that's likely for all models, as the difference between the Sport S is only $3200 more than the Sport and my guess is they will try to retain those gaps between models.
 

guarnibl

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Have they? Truly pushed through the wind, or have they just gone up against their own air resistance and claimed it was pushing theough the wind because of the common phrase? :whatsgoingon:

I travel both in the mountains and the foothills & prairies where strong sustained winds are not uncommon. Even a mild headwind at 60kmh will cause the Wrangler to want to jump from 2,000 RPM to 3,250+ just to keep the 110Kph speed limit, increase those winds, or the Speed limit to 90/120 and then the engine wants to head even higher to maintain speed with the other vehicles on the highway, and not impede traffic. Having more tq/hp at lower RPMs means that the engine can more easily push against the wind and its own resistance without getting overly excited and cratering fuel economy, and getting hot and stressed. Twice this past summer when crossing NewFoundland highlands and Saskatchewan plains I faced nearly 100Kph headwinds which meant I was going about 7 Kph under the speed limit (on rather empy highways thankfully) in order to keep my RPMs nearer 3,000, yet even then my fuel economy dropped from 12.4L/100KM (19MPG) to 16.5+L /16.8 in Sask (~14MPG) and the brief period that I did the speed limit the Pentastar wanted to stay above 4,000 RPM and crated fuel economy to 22+ L/100KM (~10-11MPG) and neither of those are desirable. Even my old Caravan (aka Ski Bus) in the early 2000s with ttheir s 3.3L engine wasn't anywhere near as affect by the strong winds of the foothills heading to Banff/Louise/Revey as the Wrangler, but moving to the 3.8 with it was definitely more relaxed. Lowering the top or removing the doors just makes it even tougher still..
I agree, but you would likely experience the exact same thing in a 5.7 Hemi. Diesel would be better. 6.4. hemi from 2500 -with- proper transmission would provide more torque but I think it would still suffer in those passes. Crossing 10,000 feet in my TJ 5.7 I -had- to stay at 4000 to maintain speed. FWIW, I get about 16 highway with my 5.7 until I get into the mountains and it drops to 9. I'm on a 5 speed auto. Even passes north of phoenix climbing to flag do the same thing. That said, you have power to pass, where you don't in the pentastar, as you are suggesting. But don't expect fuel economy.
 

The Great Grape Ape

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I'd gladly trade 50hp for an added 200lb/ft of torque, but I agree. The fact that buyers will now have an option is ultimately what Wrangler has been missing for a long time.
Yeah, that would be for the Pentastar, I meant vs the Hemi, giving back only 10-20 lbft for a 160 HP, which is why I want both if I’m adding the 100+ lbs weight of an engine over a Pentastar, then improve both by about 50% not trade one off for the other.

But IMO, the lineup is poorly populated, to me it should have the EcoDiesel, a Hemi, and then a 3.2L Pentastar sized engine, and then in the future Surpercharge or TurboCharge the 3.2L if you wanted to get rid of the Hemi. The current limeup has a Capable towing engine now, but then two mid-level engines in the Pentastar and Hurrican, neither is particularly powerful for the non-diesel crowd, and neither is particularly fuel efficient, so having them both there seems like a ‘Meh... whatever’ option that make neither seem interesting, exciting or compelling, just there by default.

Neither the Pentastar 3.6 nor the Hurrricane are bad, but neither is great either, only capable/aceptable IMO.
I will get the Pentastar because I have no other acceptable option, but I’m nowhere enar as happy about it as I would be if I could get a Hemi for $2-4K more.
 

The Great Grape Ape

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I agree, but you would likely experience the exact same thing in a 5.7 Hemi. Diesel would be better. 6.4. hemi from 2500 -with- proper transmission would provide more torque but I think it would still suffer in those passes. Crossing 10,000 feet in my TJ 5.7 I -had- to stay at 4000 to maintain speed.
What transmission was it matted to in the TJ?
Our Grand Cherokee with the 5.7 didn’t suffer as noticeably as the JK with the Pentastar, even when GC was laden with 4 large bodies ( or 2+2 ) and full of ski gear on the roof and packed inside, vs the JKU with 2 people.
@ 10K ft it would have ~280Tq&HP whereas the Pentstar is at about 100 less on both for the same weight.
Sure forced air helps at altitutde, but it’s not great with serious cold, and diesel even worse. But even though I am often in the mountains at altitude, even that is a rarity for most Wrangler owners. But for my use case specifically Hemi works best from experience.

FWIW, I get about 16 highway with my 5.7 until I get into the mountains and it drops to 9. I'm on a 5 speed auto. Even passes north of phoenix climbing to flag do the same thing. That said, you have power to pass, where you don't in the pentastar, as you are suggesting. But don't expect fuel economy.
Not expecting fuel economy, if I was I wouldn’t be driving a Wrangler, but we aren’t getting that with the Pentastar either when it struggles, only when it’s sedate; and it’s still not going to be impressive with either I just don’t like when it goes into HyperDrive just to ‘keep up’.
Same is likely with the Hurricane where it will look great on paper, but may need to be on boost quite often just to ‘keep up’ especially at higher highway speed limits.
It would have been interesting to see a properly tuned stock HEMI in the Wrangler that could take advantage of MDS and be able to put out significantly more at lower RPMs and see how much difference you could really squeeze from an unaerodynamic heavy brick from conventional approaches.
 

Nebakadnezar

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There are a few small issues with regards to this, and one big barrier which I'll cover below.

YES, Many of us have already been considering this and Supercharger / Turbo futures for our JL(U)s. Personally a diesel doesn't work for me due to cold weather requirements, so for some of us this is the route to more torque and a bit more HP for pushing against windy highways.

Probably the biggest issue is that it appears currently in the little that we know of configuations, that the capable 8HP75 transmission will only come with the EcoDiesel (next year/mid-2018), and the Pentastar and Hurricane will get the significantly weaker 8HP50 meaning that the max recommended/rated input torque will be 500NM , putting it below the current 5.7L's latest numbers (520-555+ NM), let alone well below the 392 Hemi's 640+NM of torque.

Which means in order to put even an old 5.7L Hemi in there you should have the upgraded 8HP75 transmission, requiring you to pay the exorbitant 'diesel tax' in order to get it as part of your initial Wrangler, or else include a donor transmission swap to your list of parts. Hopefully there is a Rubicon+ (ie HardRoc/Recon) with the transmission and a Pentastar making the upgrade easier.

Baring that transmission option then just a Supercharger/Turbo boost will be available for the 8HP50 Wranglers, and less so than available to the current NAG1 which is rated for 580NM. And if you are going to go forced air anyways, might just wanna get & tweak the tinyturbo4 instead, where you can at least pretend that there's warranty support for that.

I'm certain that AEV will update their Hemi swap program to include JL(U)s , but it may take a while for them to get the proper harnesses and programming for the swap. And then it will likely still cost as much as a new base JL sport to do the Hemi swap, making it tough to swallow that extra $20K+ for soemthing that seems like it should be a stock option like in the GC, and that's just the engine swap.

Of the two Hemi options I would prefer the Gen3 (aka Gen 2.1) 5.7L for weight considerations. The Gen2+ has added lots of HP and improved torque delivery (no longer such a dog vs the 6.4's early-on torque they are now both very good at quicker power delivery. The new (2016+) Mopar crate 5.7's 400+lbft/400+HP is more than enough torque for me to get up a mountain side and also more than enough HP boost per RPM over the Pentastar to overcome 100+KPH headwinds in the prairies when driving the Wrangler brick with the top open without requiring 4,000+ RPM to do so, plus MDS should make it about as efficient.

I still think the Hemi 5.7 is the perfect fit for a Wrangler for the trail and the highway, but with the external EPA pressures, and some of the diesel hype that plays to that and other considerations that create false narratives (like towing, only remembering the GC, forgetting the RAM of course), unfortunately the Wrangler will never get the stock Hemi that is likely it's best fit if utility/reliability/price was the primary determining factors, and not CAFE considerations and image.
Maybe a dumb question, but what is wrong with the ecodiesel in cold weather? I live up at 9400' and was pretty much decided on the diesel for the extra torque.
 

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