HEMI swap for the JL?

The Great Grape Ape

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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.
Just to be clear for this, It’s not about the altitude, just about the cold, where there’s two issues.
In truly cold weather diesel freezes or gels/waxes up clogging the fuel filter (even with Arctic diesel that we get here waxes up around -40 +/- and freezes at -43, let alone Winter diesel).
If the vehicle is plugged in or in covered parking all the time it won’t matter, but leaving it unplugged for extended periods needing to use it in -40 weather on a consistent basis, diesel is not reassuring. And when it gets truly cold then the problem can occur further back in the fuel system prior to the fuel filter heater, so being plugged in can affect that unless you extend heater back the fuel system. But this is an issue for just a small number of us who aren’t just driving it from plug to plug or cover to cover, most people won’t have an issue in the lower 49th because only a few spots even get that cold (wind chill doesn’t count).

The other issue is that in order to get lower cloud points those Winter/Arctic additives cost you fuel efficiency because the additives aren’t as energy rich as the diesel itself, it is similar to what happens when running ethanol in a gasoline engine.

Neither of those issues make it an attractive option for me, especially since sometimes I will head into the backcountry to ski or snowshoe etc and it will start ‘warmer’ and suddenly drop off the scale, or during races I will need to park on the hill or unplugged in the lot near our comms trailer for ~12hours. However, this isn’t an issue for most people, but it is a big issue for my use-case.





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Nebakadnezar

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Just to be clear for this, It’s not about the altitude, just about the cold, where there’s two issues.
In truly cold weather diesel freezes or gels/waxes up clogging the fuel filter (even with Arctic diesel that we get here waxes up around -40 +/- and freezes at -43, let alone Winter diesel).
If the vehicle is plugged in or in covered parking all the time it won’t matter, but leaving it unplugged for extended periods needing to use it in -40 weather on a consistent basis, diesel is not reassuring. And when it gets truly cold then the problem can occur further back in the fuel system prior to the fuel filter heater, so being plugged in can affect that unless you extend heater back the fuel system. But this is an issue for just a small number of us who aren’t just driving it from plug to plug or cover to cover, most people won’t have an issue in the lower 49th because only a few spots even get that cold (wind chill doesn’t count).

The other issue is that in order to get lower cloud points those Winter/Arctic additives cost you fuel efficiency because the additives aren’t as energy rich as the diesel itself, it is similar to what happens when running ethanol in a gasoline engine.

Neither of those issues make it an attractive option for me, especially since sometimes I will head into the backcountry to ski or snowshoe etc and it will start ‘warmer’ and suddenly drop off the scale, or during races I will need to park on the hill or unplugged in the lot near our comms trailer for ~12hours. However, this isn’t an issue for most people, but it is a big issue for my use-case.
Bustin out "cloud points". Nice! Someone's got a chemistry background, haha!! Thanks for the info. We are in the Rockies and get a ton of snow, but I've never seen anything close to -40 around here. Thanks for the on point response!
 

WXman

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Yep, never been -40°F here either. Our record is -37°F. In the last several years, the coldest I've had here is -10°F or so. But still, I don't see any issues with diesels and I don't know anybody who has issues with diesels. You plug them up when you can, but even if you can't today's diesels will start in the cold and run fine.

As far as why FCA doesn't and never will put a V8 in a Wrangler ever again, that's been discussed many times. A former lead engineer stated that making the V8 work in the engine bay was simply not doable from a practical and safety standpoint. Remember, aftermarket companies don't have to go through the crash testing and durability standards that a major automaker does. AEV dropping a V8 into a Wrangler and a shade tree mechanic at home dropping a V8 into a Wrangler does NOT mean that FCA can drop V8s into Wranglers on the assembly line.
 

robplumm

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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.

.
Arctic diesel or Anti-gel additives don't work up there? (not that it gets nearly cold enough here for them...just wondering)

ETA: Should have kept scrolling :D see the extensive answer now
 

Solidaxle

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There’s a company or two that already have Hemi conversions for the JL and the JT pick up truck is going to be a prime candidate for a Hemi conversion. They expect that to be done before Sema of this year.
 

guarnibl

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There’s a company or two that already have Hemi conversions for the JL and the JT pick up truck is going to be a prime candidate for a Hemi conversion. They expect that to be done before Sema of this year.
There was one at Barrett Jackson, forget the name -- that has a Hellcat swapped JL. It may or may not have been on Dana 44's :cwl:
 

eddybarba

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America's most wanted 4x4 in michigan is doing 6.4 and hellcat swaps already
 

BenDiesel

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Dakota customs is offering kits now
 

custmfxwg

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Not sure if anyone has considered doing the swap themselves rather than paying a company to do it. The harness is available from Mopar, as is the crate engine; $1585 for the harness, $5600 for the 5.7L Hemi, and $99 for motor mounts. There are a few other things you'd need, but the harness is plug & play on the engine side with about 6-8 splices under the dash. This makes this a less than $10K swap rather than a $20K-$50K option.
 

Markham

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I’d love to ride in one of those.
 

stickshifter

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On the need for a V8: of course "need" is subjective, and different people have different wants or needs, and we can all get by with the Wrangler's Pentastar V6. But if you live at elevation - or traverse the plains regularly like Grape Ape - the current naturally aspirated V6 engines found in midsize trucks and in the Wrangler have difficulty sustaining speed, especially going up hill at 8,000-10,000 feet. Most of these V6 engines lack low-end torque which is really noticeable going up steep inclines both on-road and off-road. Right now I am driving a 2017 Tacoma (3.5 V6 manual transmission), and in my commute I downshift to first gear on tight turns going up the steep sections (I live at 8,500 feet, and work at 5,500 feet). In my 1997 Tacoma I could take these same sections in second gear. Going up steep dirt roads to get to trailheads for hiking or biking I also am stuck in first gear. I would be thrilled with a small V8.

We all know that if you could get a Wrangler with a factory V8 sales would go through the roof. Its a shame Jeep (FCA) doesn't have a small V8, like the Chevy EcoTec 5.3, which might be a better fit for the Wrangler both in terms of fuel consumption (a little better than the Hemi) and in the engine bay. While both engines are reliable, the 5.3 is a push-rod design that is more compact than the Hemi, and the aluminum block 5.3 is lighter than the Hemi. In addition, the compact 5.3 would have a lower center of gravity than the Hemi. Its also got plenty of power (355 hp, 383 lb⋅ft of torque). Not as strong as the 5.7 Hemi, or as torquey as the 3.0 Eco-diesel, but - in my opinion - great for a Wrangler running 33-37 inch tires. Diesels have some drawbacks, and for many people, are not a great choice. Short commutes are not good in a diesel, gelling of fuel in cold weather (Grape Ape is on the nose), you don't get heat on cold days until the engine warms up (heavy duty pickups have after-market solutions in the form of secondary heaters, but I don't know if these would work in the smaller Wrangler platform), regen cycles, and DEF fluid stand out as some drawbacks to diesels.

I'm not knocking the Hemi 5.7 - that is a great engine - and I would buy a Wrangler in a heartbeat if it came from the factory with a 5.7 Hemi. I'm just wasting time fantasizing about alternatives...
 

rayzjeep

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Not sure if anyone has considered doing the swap themselves rather than paying a company to do it. The harness is available from Mopar, as is the crate engine; $1585 for the harness, $5600 for the 5.7L Hemi, and $99 for motor mounts. There are a few other things you'd need, but the harness is plug & play on the engine side with about 6-8 splices under the dash. This makes this a less than $10K swap rather than a $20K-$50K option.
Wonder if there would be a market for a harness that's plug and play on both ends....and I imagine the 8 speed could hold up to the 5.7l. I don't get how/why these shops are charging 25k+ for this swap. Get it down to 10-12k out the door and I'd probably consider it.
 

AlrightAlready

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The harness is plug & play on the engine side with about 6-8 splices under the dash.
Could you elaborate on this point with some proof? From my understanding, this swap is much more significant wiring wise.
 

ered33

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I also have questions regarding this harness and ecm kit. It doesn't specify anywhere that I can find if it's for manual or auto or if there's a choice. Another big question is will it interface with the can line? All new ECM's require a VIN be applied and all other modules need to see it matching. Also, will there be any kind of writing or coding software available for this ECM? I am currently just starting an engine build based off of a 5.7 that is .020 over with a 4.050 stroke. Also adding a ported 6.1 SRT intake with ported Edelbrock RPM Performer heads and a .560ish lift cam with 235 duration. So even though I will be a 392 in size, a stock 392 tune will not work very well. I have also been looking for any kind of tuning software like HP Tuner that works with Chrysler. There are quite a few companies doing the hemi swaps now so they have to be using something! Anyone have more information it would be greatly appreciated!!!
 

custmfxwg

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Could you elaborate on this point with some proof? From my understanding, this swap is much more significant wiring wise.
I also have questions regarding this harness and ecm kit. It doesn't specify anywhere that I can find if it's for manual or auto or if there's a choice. Another big question is will it interface with the can line? All new ECM's require a VIN be applied and all other modules need to see it matching. Also, will there be any kind of writing or coding software available for this ECM? I am currently just starting an engine build based off of a 5.7 that is .020 over with a 4.050 stroke. Also adding a ported 6.1 SRT intake with ported Edelbrock RPM Performer heads and a .560ish lift cam with 235 duration. So even though I will be a 392 in size, a stock 392 tune will not work very well. I have also been looking for any kind of tuning software like HP Tuner that works with Chrysler. There are quite a few companies doing the hemi swaps now so they have to be using something! Anyone have more information it would be greatly appreciated!!!
Here's a link to the mopar instructions for the engine and the harness. https://www.mopar.com/moparsvc/pim/media?id=9012411170846. It looks like it's not as simple as a splice connector, but if you have time and the patience it doesn't look too difficult. There is at least one requirement to take it to the dealer for the "pedal Learn" function. The info in the instructions under "additional parts" talks briefly about a clutch and flywheel, so it appears either automatic or manual can be used.
 

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