JKOwners Forum banner
1 - 20 of 30 Posts

·
Registered
Joined
·
100 Posts
Discussion Starter · #1 ·
I haven't posted in a VERY long time on here but I am just starting to gather information for the hemi swap I plan to do. I wanted to ask a few questions or request a few links to write ups if you feel it warrants. I have a couple of goals in mind and a couple of targets already for sourcing. I have access to a 5.7 with 5k miles and an 8hp70 transmission as a possibility but I have a 2015 Jeep Wrangler Unlimited Rubicon and I know the NAG1 is capable of handling the 5.7. Would it make more sense to try to find a 6.4 engine only and mate it up with the NAG1 or worth the extra to get the 8hp70 in there? My goal is to try to keep the cost under 10-12k total (my wife's uncle is a mechanic and willing to help me through the install process). Any ideas or pointers or minefields I should steer clear of? Thanks in advance.

Oh and my Jeep...2015 Jeep Wrangler Rubicon Unlimited, 3.5" rockkrawler lift with 4" synergy springs, dana 60 rear with dana 44 up front that is armored up. Drive shafts are upgraded. SPOD is a concern for placement but I will burn that bridge when I get there (although my lockers are hard wired into it at the moment so I will def have to figure that part out).
 

·
Registered
Joined
·
100 Posts
Discussion Starter · #2 ·
I haven't posted in a VERY long time on here but I am just starting to gather information for the hemi swap I plan to do. I wanted to ask a few questions or request a few links to write ups if you feel it warrants. I have a couple of goals in mind and a couple of targets already for sourcing. I have access to a 5.7 with 5k miles and an 8hp70 transmission as a possibility but I have a 2015 Jeep Wrangler Unlimited Rubicon and I know the NAG1 is capable of handling the 5.7. Would it make more sense to try to find a 6.4 engine only and mate it up with the NAG1 or worth the extra to get the 8hp70 in there? My goal is to try to keep the cost under 10-12k total (my wife's uncle is a mechanic and willing to help me through the install process). Any ideas or pointers or minefields I should steer clear of? Thanks in advance.

Oh and my Jeep...2015 Jeep Wrangler Rubicon Unlimited, 3.5" rockkrawler lift with 4" synergy springs, dana 60 rear with dana 44 up front that is armored up. Drive shafts are upgraded. SPOD is a concern for placement but I will burn that bridge when I get there (although my lockers are hard wired into it at the moment so I will def have to figure that part out).

Oh and I am not interested in an LS swap. Mainly because my wifes family has a long history of being MOPAR people and the thought of doing that would just upset him...lol.
 

·
Registered
Joined
·
8,419 Posts
The 8hp70 is quite superior to the NAG1 in terms of keeping the motor in its power band. The higher first gear is also going to make it feel quite pep-ier and if I were going through the trouble of a swap, I would want the newer trans. Both are rated for about the same amount of torque so should be fine behind a 5.7

That said, if you are going for a 6.4 which is mated to the 8HP70 in things like the Grand Cherokee, I would want a higher rated 8HP like the 8HP90 but I dont see you doing a 6.4/8HP90 swap for your budget. 6.4s are way harder to find for a deal than a 5.7
 

·
Premium Member
Joined
·
211 Posts
I am about to have a Dakota customs 6.4 and 8 speed kit installed into my 2008 JK. I also doing a Dyntrac serious performance 44/60 combo wiht 4:88 gears. ill let you know how the 6.4 and 8 speed perform once installed .
 

·
Registered
Joined
·
154 Posts
I am about to have a Dakota customs 6.4 and 8 speed kit installed into my 2008 JK. I also doing a Dyntrac serious performance 44/60 combo wiht 4:88 gears. ill let you know how the 6.4 and 8 speed perform once installed .
Why a Dyna 44/60 instead of a 60/60 or a Tera/Currie?
 

·
Registered
Joined
·
240 Posts
I recently got my JK back from JSS with a 392/8HP70 combo and it’s a world of difference. Shifting is so smooth you can’t even tell when it happens. Drove up to Tahoe over Donner Pass (7k feet) and it was accelerating in 7th gear at 80mph. Running UD60s with 4.88 gears, which are perfect for 38-40 inch tires.

If you’ve got the resources, then do the 8sp without a doubt.
 

·
Premium Member
Joined
·
211 Posts
I recently got my JK back from JSS with a 392/8HP70 combo and it’s a world of difference. Shifting is so smooth you can’t even tell when it happens. Drove up to Tahoe over Donner Pass (7k feet) and it was accelerating in 7th gear at 80mph. Running UD60s with 4.88 gears, which are perfect for 38-40 inch tires.

If you’ve got the resources, then do the 8sp without a doubt.
Awesome! I can’t wait to get mine done ! What axles are you running? I’m trying to get a rear drive shaft length figured out .


Sent from my iPhone using Tapatalk
 

·
Premium Member
Joined
·
211 Posts
UD60s. T case moves back 2”, so you’ll need to lengthen the front driveshaft.
So you need to add to the front and shorten the rear ? I have the dynatrac serious performance 44 front and 60 rear . The 60 rear is about 2 inches longer than the stock 44 rear .




PS
We have kinda hijacked the original post …..


Sent from my iPhone using Tapatalk
 

·
Premium Member
Joined
·
211 Posts
Dont play the length guessing game. Wait until everything is in and measure. Yes it will be more down time but I think well worth the outcome knowing the correct lengths are in for your specific build.
Yea , I’m holding off until the engine and trans go in . I’m doing the axle install this weekend. Then a local shop is installing the engine kit .



Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
100 Posts
Discussion Starter · #19 ·
I recently got my JK back from JSS with a 392/8HP70 combo and it’s a world of difference. Shifting is so smooth you can’t even tell when it happens. Drove up to Tahoe over Donner Pass (7k feet) and it was accelerating in 7th gear at 80mph. Running UD60s with 4.88 gears, which are perfect for 38-40 inch tires.

If you’ve got the resources, then do the 8sp without a doubt.
What transfer case did they go with? I am told I will need to change out the tcase on my rubicon if I do the 8hp70 transmission.
 
1 - 20 of 30 Posts
Top