Gen III Hemi Swap into TJ Reference Guide & Swap Info

[MichaelGH]

Good info, but Just a couple of clarifications. The coil on plug setup did not start in ‘07. My ‘06 runs the coil on plug - but I’m not sure what year they started. It is a nicer setup - especially if you hate spark plug wires (and LS’s…).

The ‘03 to ‘08 Gen III Hemi will work, but for the stock gauges in the ‘01 to ‘06 TJ to work you need to run an ‘05 (or prior) ECU. The ‘06 to ‘08 Hemi (at least in the Ram) used a CAN BUS setup, which is not compatible with the TJ cluster. For the ‘01 and prior TJ, you will need to source an ‘02 to ‘06 TJ gauge cluster, or go custom gauges. Further, if you use the wiring harness from an ‘06+ Hemi, the harness has to be modified to ‘05 specs (among the other necessary changes).

You are correct. On the Ram engine the dual plug coil started in ‘06. Good catch…

The ‘05 Ram ECU seems to work well with the ‘01-‘06 TJ clusters. I run the ‘05 Ram ECU and an ‘01 TJ cluster in my Jeep. Works beautifully…

 

[NashvilleTJ]

You are correct. On the Ram engine the dual plug coil started in ‘06. Good catch…

The ‘05 Ram ECU seems to work well with the ‘01-‘06 TJ clusters. I run the ‘05 Ram ECU and an ‘01 TJ cluster in my Jeep. Works beautifully…

Interesting. As I understand it, the '97 - '01 TJ platform uses a CCD Bus system, which should not be able to communicate with the '05 Hemi ECU, which runs PCI. Hemi ECU's ran PCI from '03 - '05. The TJ platform ran the PCI bus from '02 - '06. I wonder if it was a mid-year '01 conversion?

But again, just my understanding - I could be off by a year.

 

[MichaelGH]

Interesting. As I understand it, the '97 - '01 TJ platform uses a CCD Bus system, which should not be able to communicate with the '05 Hemi ECU, which runs PCI. Hemi ECU's ran PCI from '03 - '05. The TJ platform ran the PCI bus from '02 - '06. I wonder if it was a mid-year '01 conversion?

But again, just my understanding - I could be off by a year.

I’m not sure. Hotwireauto states on the website that ‘97-‘00 clusters would need to be replaced with a newer TJ gauge cluster. So that is what I went by…

 

[NashvilleTJ]

And a little eye candy for the thread:

And a little insight into my build. Prior to the Hemi I ran a supercharger on the 4.0. It made about 300 hp and 400 torque at the flywheel. The '03 - '08 Gen III Hemi made something like 345 hp and 375 torque. No way I was going through all that work for a little more hp and less torque. So I built the Hemi. Molnar forged crank, pistons and connecting rods, 10.5:1 compression, bored 20 over, a mild cam and some head work. I also had ATS do a stage 4 build on the 545FRE to take 700 hp. The math puts it at about 399 cubes, but I call it a 392 because, well, 392...

On the chassis dyno, with my crazy heavy drive train, it made about 390 at the wheels, and about the same torque. Although I've never had it on an engine dyno, it's likely north of 500 at the crank.

My biggest regret was not doing more with the heads - which is the big limiting factor on this version of the Hemi. The subsequent Eagle heads were a huge improvement - flowed significantly more, and therefore make a good bit more power. I've looked a few times at installing a set of ported Eagle heads, and I've come close to pulling the trigger a few times, but it would also require rebuilding the exhaust as it would need a new set of headers to handle the different exhaust port configuration. Building the exhaust was the most challenging part of my build - don't really want to do that again...

Finally, the exhaust was another mistake I made. I run 2.5 pipes through 2 2.5" cats, and then into a custom Y-Pipe - into a 2.5" muffler and tail pipe. This would have been fine for a stock '06 Hemi. What I should have done is go dual all the way out the back, or at least merge into a 3" pipe, muffler and tail pipe. Flyin' Ryan told me I'm likely giving up a good chunk of HP because of that. But, it runs and sounds good. I guess that's another reason to do the Eagle heads...

 

[hardtailpan]

1) I have the Savvy 1.25” body lift so I went with the MORE 1” taller bracket. Just to keep the steering shaft in better alignment. You are correct that the four-cylinder bracket can be used though…

2) The 2005 Ram 5.7 Hemi Power steering pump works beautifully with the TJ steering gear. At least it does with the early box. I am not sure about the later Mercedes box…

3) A TJ 4.0 power steering pressure line works perfectly between the Ram pump and the earliy TJ steering gear. You only have to bend the one end a little to go in the Ram power steering pump…

The low pressure line needs to be fabricated though. You need to go from the 5/8” hose nipple on the Ram reservoir to the early TJ steering gear low pressure port. It can be done several ways…

4) I actually bought a hydraulic crimper and made all my own AC lines. An AC shop can easily do it though…

5) I do not have cruise control. I believe Hotwireauto has an aftermarket kit that will work…

Thanks!

 

[Daubie3]

Another option that I went with was replacing the cross wire plug wire system with the shorty plug wires that do the same thing as the later model black plastic valve covers with the dual plug coils. I wanted to keep the aluminum valve covers and paint them HEMI orange just mostly because I'm old school and like the retro look. Off the top of my head I don't remember who I got the shorty plug wires from because it was over 2 years ago when I bought most of the things for my swap before putting on hold starting with the pandemic..
They may not be quite as clean as the bigger coils, but again "old school" and I like the looks of the wires. Eye of the beholder.

They do come in a few different colors, I liked the red...

 

[NashvilleTJ]

Another option that I went with was replacing the cross wire plug wire system with the shorty plug wires that do the same thing as the later model black plastic valve covers with the dual plug coils. I wanted to keep the aluminum valve covers and paint them HEMI orange just mostly because I'm old school and like the retro look. Off the top of my head I don't remember who I got the shorty plug wires from because it was over 2 years ago when I bought most of the things for my swap before putting on hold starting with the pandemic..
They may not be quite as clean as the bigger coils, but again "old school" and I like the looks of the wires. Eye of the beholder.

They do come in a few different colors, I liked the red...

View attachment 390636

I gotsta admit, the main reason I went with these Accel buggers was that they matched the rig…

 

[Hammer_c]

@Wildman saved me some time

The Hemi swap will resume once I get situated after the move this summer. I have been reading good things about some of the aftermarket controllers for the 8HP transmissions, so I may end up doing something with that instead.

Alternatively, Holley now offers a controller for the Eagle motors + 46RE transmissions, which is actually a better transmission (wow, never thought I'd be saying that about a 46RE!!!) for higher horsepower builds. Since everything rusts apart in PA, I may be on the prowl for a 98 5.9L ZJ in the junkyards and snatch up the trans from it (the Jeep RE's have the starter on the right-hand side).

I can confirm a 2019 Ram 8HP70 will work in a TJ with a 6.1. I’m wrapping up the swap and have 50 or so miles on it. I’m using a harness from Hotwire and a trans controller from Russel, at Sound German.

 

[Hemic]

I can confirm a 2019 Ram 8HP70 will work in a TJ with a 6.1. I’m wrapping up the swap and have 50 or so miles on it. I’m using a harness from Hotwire and a trans controller from Russel, at Sound German.

I just pulled out a 6.1 out of a Challenger working on swapping the pan to a rear sump oil pan and a Holley mid mount accessory drive. I'll be sending my fuse box/harness to Hotwire for the Hemi swap and 545RFE using '08 Ram ECM. If I were to use a 8HP70 tranny, does Hotwire need to build the wiring differently? I've got Holley motor mounts and transmission adapter for 545RFE. Do I need to fabricate a transmission mount adapter for 8HP70? Does it require a 1" body lift or can be done with no body lift? Thanks for any input...

 

[Hammer_c]

I just pulled out a 6.1 out of a Challenger working on swapping the pan to a rear sump oil pan and a Holley mid mount accessory drive. I'll be sending my fuse box/harness to Hotwire for the Hemi swap and 545RFE using '08 Ram ECM. If I were to use a 8HP70 tranny, does Hotwire need to build the wiring differently? I've got Holley motor mounts and transmission adapter for 545RFE. Do I need to fabricate a transmission mount adapter for 8HP70? Does it require a 1" body lift or can be done with no body lift? Thanks for any input...

Nice! The 6.1 8 speed swap was relative easy if you can fabricate. Without hijacking the thread I can shed some light on the swap. When I get time I’ll do a detailed write up.

I have over 1,000 miles and loving it. Did the Rubicon a few weeks ago and plenty of on/off-road with no issues The 8 speed feels like you have an extra 30-40 HP vs the 5 speed and you can hit 100mph+ very easily. Not that a jeep should be going that fast.

As far as I know there are only 3 TJs running the 8 speed and we are all slightly different. There is not a lot of support, however Hotwire and Jeep Speed Shop helped where they could, but I was left to figure a lot out on my own.

The trans harness is completely different since it’s wired as a standalone hot rod harness with its own computer and canbus input.

I made my own gas pedal bracket, trans mount, exhaust, AC lines, and power steering lines. I re-used my TJ PSC pump since the bolt holes lined up perfectly, but had to make a simple spacer to align the belt.

My 6.1 came from a Cherokee and I didn’t need to change the accessory drive since everything fit…closely.

I used the Holley mounts and they worked great once the motor is in but it’s a PIA getting the motor and trans in.

You have to run a 1” body lift. I spent weeks trying to fit the exhaust and trans and couldn’t fit them without a lift. I am running a belly up skid plate so that might have played a part.

Stock SRT manifolds will not fit on the driver side with a long arm set up. Spent countless hours trying. Ended up using a modified shorty holly header to fit everything.

For my 2000 TJ I used a 05 ram computer, flashed the TCM in the trans for a 16 challenger.

6.1 and the 8HP70 bolts right up but I needed a different starter, shifter and trans dust shield.

Feel free to DM if you have any more questions.

 

[Wildman]

Nice! The 6.1 8 speed swap was relative easy if you can fabricate. Without hijacking the thread I can shed some light on the swap. When I get time I’ll do a detailed write up.

I have over 1,000 miles and loving it. Did the Rubicon a few weeks ago and plenty of on/off-road with no issues The 8 speed feels like you have an extra 30-40 HP vs the 5 speed and you can hit 100mph+ very easily. Not that a jeep should be going that fast.

As far as I know there are only 3 TJs running the 8 speed and we are all slightly different. There is not a lot of support, however Hotwire and Jeep Speed Shop helped where they could, but I was left to figure a lot out on my own.

The trans harness is completely different since it’s wired as a standalone hot rod harness with its own computer and canbus input.

I made my own gas pedal bracket, trans mount, exhaust, AC lines, and power steering lines. I re-used my TJ PSC pump since the bolt holes lined up perfectly, but had to make a simple spacer to align the belt.

My 6.1 came from a Cherokee and I didn’t need to change the accessory drive since everything fit…closely.

I used the Holley mounts and they worked great once the motor is in but it’s a PIA getting the motor and trans in.

You have to run a 1” body lift. I spent weeks trying to fit the exhaust and trans and couldn’t fit them without a lift. I am running a belly up skid plate so that might have played a part.

Stock SRT manifolds will not fit on the driver side with a long arm set up. Spent countless hours trying. Ended up using a modified shorty holly header to fit everything.

For my 2000 TJ I used a 05 ram computer, flashed the TCM in the trans for a 16 challenger.

6.1 and the 8HP70 bolts right up but I needed a different starter, shifter and trans dust shield.

Feel free to DM if you have any more questions.

Looking forward to reading your thread on this. Sounds like a very cool setup.

 

[Hemic]

Looking forward to reading your thread on this. Sounds like a very cool setup.

Wildman, I believe you're in WA state. I contacted Russell at Sound German and he said he can get the 8hp70 working using a standalone TCM. Is this what you have done? do you know anyone locally in the Seattle are who could install this? I'm trying to keep all my factory gauges working. Thanks!

 

[Hemic]

Looking forward to reading your thread on this. Sounds like a very cool setup.

Nice! The 6.1 8 speed swap was relative easy if you can fabricate. Without hijacking the thread I can shed some light on the swap. When I get time I’ll do a detailed write up.

I have over 1,000 miles and loving it. Did the Rubicon a few weeks ago and plenty of on/off-road with no issues The 8 speed feels like you have an extra 30-40 HP vs the 5 speed and you can hit 100mph+ very easily. Not that a jeep should be going that fast.

As far as I know there are only 3 TJs running the 8 speed and we are all slightly different. There is not a lot of support, however Hotwire and Jeep Speed Shop helped where they could, but I was left to figure a lot out on my own.

The trans harness is completely different since it’s wired as a standalone hot rod harness with its own computer and canbus input.

I made my own gas pedal bracket, trans mount, exhaust, AC lines, and power steering lines. I re-used my TJ PSC pump since the bolt holes lined up perfectly, but had to make a simple spacer to align the belt.

My 6.1 came from a Cherokee and I didn’t need to change the accessory drive since everything fit…closely.

I used the Holley mounts and they worked great once the motor is in but it’s a PIA getting the motor and trans in.

You have to run a 1” body lift. I spent weeks trying to fit the exhaust and trans and couldn’t fit them without a lift. I am running a belly up skid plate so that might have played a part.

Stock SRT manifolds will not fit on the driver side with a long arm set up. Spent countless hours trying. Ended up using a modified shorty holly header to fit everything.

For my 2000 TJ I used a 05 ram computer, flashed the TCM in the trans for a 16 challenger.

6.1 and the 8HP70 bolts right up but I needed a different starter, shifter and trans dust shield.

Feel free to DM if you have any more questions.

Hi Hammer, thank you for your detailed explanation. I've seen a number of TJ's with no body lift Hemi swaps. Is the 8 speed causing the clearance issues or the exhaust? I have the factory belly pan, which I think could provide more clearance comparing to the belly up. I'm really wanting to stay away from the body lift, if there's any way around it. I heard the 6.4 log style manifolds will fit the 6.1 and help with clearance. Haven't tried them yet. Believe the Holley BlackHeart shorties are very similar. (Holley website shows them with round ports, while they should be D ports if they're for the 6.4, am I correct?)

The Teraflex gas pedal bracket was showing available on 4wp until a few months ago... but apparently it's not available anywhere...

Did you have to modify the Hotwire harness with the 8HP?

 

[Wildman]

Wildman, I believe you're in WA state. I contacted Russell at Sound German and he said he can get the 8hp70 working using a standalone TCM. Is this what you have done? do you know anyone locally in the Seattle are who could install this? I'm trying to keep all my factory gauges working. Thanks!

I don't have a Hemi I've got it's earlier brother the magnum V-8. I have a 5.9 with a stroker kit making it a 6.7. Look at the build thread linked in the bottom of my sig.
Yes I'm in WA and I might know a shop that can do this conversion for you. Contact this person.

Where in WA are you located? I'm 93 miles east of Seattle & about 15 miles west of Ellensburg.

Hi Hammer, thank you for your detailed explanation. I've seen a number of TJ's with no body lift Hemi swaps. Is the 8 speed causing the clearance issues or the exhaust? I have the factory belly pan, which I think could provide more clearance comparing to the belly up. I'm really wanting to stay away from the body lift, if there's any way around it. I heard the 6.4 log style manifolds will fit the 6.1 and help with clearance. Haven't tried them yet. Believe the Holley BlackHeart shorties are very similar. (Holley website shows them with round ports, while they should be D ports if they're for the 6.4, am I correct?)

The Teraflex gas pedal bracket was showing available on 4wp until a few months ago... but apparently it's not available anywhere...

Did you have to modify the Hotwire harness with the 8HP?

Why don't you want to use a body lift? It makes many things easier. You need to use a quality one like from Savvy or BMB.

 

[Wildman]

Here's one 6.1 swap that was just completed recently.

https://wranglertjforum.com/threads/6-1-ljr-build.67130/

Here's another one that just got finished not too long ago.

https://wranglertjforum.com/threads/daubies-at-home-hemi-conversion.67473/

And then there is Jeff's Hemi swap

https://wranglertjforum.com/threads/nashville-tjs-build-continued.42035/

There is a LOT of information out there now on doing Hemi swaps into TJ/LJ's. I did my V-8 swap back in 2006 but bought my engine in 2005. At the time either a Hemi or LS take out was $10K++ so I went the magnum route. For 2002 & older TJ's the magnum is the inexpensive V-8 swap. They don't make the same HP & TQ as a Hemi or LS but they still are better than stock options. And one of the nice things is that the PCM mounts in the stock location and it talks to the Jeep dash so you keep your stock gauges. And it's only about 14 wires to blend the Jeep & donor harnesses together.
I've been in the middle of a complete rebuild of my TJ after my rig was parked for 10 years due to health issues. IT's been a long (slow) rebuild and I'm on my 3rd year of working on it.

I'd LOVE to throw a 8HP70 behind my V-8. Having 8 gears to choose from instead of only 4 would be really nice.

 

[Hammer_c]

Wildman, I believe you're in WA state. I contacted Russell at Sound German and he said he can get the 8hp70 working using a standalone TCM. Is this what you have done? do you know anyone locally in the Seattle are who could install this? I'm trying to keep all my factory gauges working. Thanks!

I’m running factory gauges from an 04 rubicon. The TCM on the 8HP is in the trans. You’ll need a signal from coil #8, converter box for a can input and PSC controller. At least that’s what Russell sent me.

 

[Hammer_c]

Hi Hammer, thank you for your detailed explanation. I've seen a number of TJ's with no body lift Hemi swaps. Is the 8 speed causing the clearance issues or the exhaust? I have the factory belly pan, which I think could provide more clearance comparing to the belly up. I'm really wanting to stay away from the body lift, if there's any way around it. I heard the 6.4 log style manifolds will fit the 6.1 and help with clearance. Haven't tried them yet. Believe the Holley BlackHeart shorties are very similar. (Holley website shows them with round ports, while they should be D ports if they're for the 6.4, am I correct?)

The Teraflex gas pedal bracket was showing available on 4wp until a few months ago... but apparently it's not available anywhere...

Did you have to modify the Hotwire harness with the 8HP?

Hey Hemic, the 8 speed is not the issue, but the clearance from the 3” exhaust, suspension, Atlas, and driveshaft became an issue on mine. I’m running 37s and wanted to keep a low CG and ran into clearance issues with the amount of travel on a 4” lift. I’d try it with the factory skid first since you can always add a body lift.

Even with the shorty black hearts I had to cut and turn down the driver side to clear the tub (part BH2375) Not sure on the long tubes.

Teraflex bracket is discontinued and has been for awhile, I confirmed this with them. The bracket was pretty simple to make with a vice and a welder.

Hotwire uses Sound Germans harness and meshes it with together for a plug and play install.

 

[Hammer_c]

Here's one 6.1 swap that was just completed recently.

https://wranglertjforum.com/threads/6-1-ljr-build.67130/

Here's another one that just got finished not too long ago.

https://wranglertjforum.com/threads/daubies-at-home-hemi-conversion.67473/

And then there is Jeff's Hemi swap

https://wranglertjforum.com/threads/nashville-tjs-build-continued.42035/

There is a LOT of information out there now on doing Hemi swaps into TJ/LJ's. I did my V-8 swap back in 2006 but bought my engine in 2005. At the time either a Hemi or LS take out was $10K++ so I went the magnum route. For 2002 & older TJ's the magnum is the inexpensive V-8 swap. They don't make the same HP & TQ as a Hemi or LS but they still are better than stock options. And one of the nice things is that the PCM mounts in the stock location and it talks to the Jeep dash so you keep your stock gauges. And it's only about 14 wires to blend the Jeep & donor harnesses together.
I've been in the middle of a complete rebuild of my TJ after my rig was parked for 10 years due to health issues. IT's been a long (slow) rebuild and I'm on my 3rd year of working on it.

I'd LOVE to throw a 8HP70 behind my V-8. Having 8 gears to choose from instead of only 4 would be really nice.

Thanks for the links Wildman, there’s a wealth of good info in there. To clarify there isn’t a lot info on swapping an 8 speed into a TJ and I’ll help out where I can.

 

[Wildman]

Thanks for the links Wildman, there’s a wealth of good info in there. To clarify there isn’t a lot info on swapping an 8 speed into a TJ and I’ll help out where I can.

No problem.
I did my first swap years ago and enjoyed it but there were times I wished I had more gears on the highway. My Jeep has turned into more of a trailer queen now so it isn't as important.,

I will second your comment about fitting a 3" exhaust under our TJ's and needing a body lift. I've had many issues getting things to fit properly. I'd started out planning on running shorty headers and had to go back to block huggers & I'm still having clearance issues. I've got my fingers crossed that I'll be driving my TJ here in the next few days. It's been a long road.

 

[NashvilleTJ]

…. I've got my fingers crossed that I'll be driving my TJ here in the next few days. It's been a long road.

A long and winding road…