Introduction & Hemi Basics
If anyone has ever spent time on the Wrangler TJ Forum, you may have seen my Gen III Hemi swap info there. I figured since I'm going through the work on my JKU, that it just makes sense to do that here as well. There are plenty of YouTube videos, some done by vendors selling swap parts (such as Jeep Speed Shop, which is who I'm primarily sourcing my part from), and some done by people trying to help others out.
Some worthwhile videos to check out:
JKB Off-Road: https://www.youtube.com/@JKB_OFFROAD_olllllllo
JK Gear and Gadgets: https://www.youtube.com/@JKGearandGadgets
Jeep Speed Shop: https://www.youtube.com/@jeepspeedshop
While I love YouTube videos, and I may even make a few of my own in those instances where I think other videos may fall short, I think there's a lot to be said of having a step-by-step forum post that can be referenced, corrected, and added to as needed. I'll be building this thread out as I go through my swap, where I'll be putting a 5.7L VVT LX Hemi and 8HP70 into my 2008 JKU. I'll have some info about the Hemi swap in My Build Thread, but the bulk of the technical information, references, and more, will be saved here for future easy reference by myself and by anyone else who needs it.
If there's something I glossed over or something you want expanded up, just let me know!
What is a Hemi?
The Gen III Hemi ("gen three", or generation three), is, as the name would suggest, the third iteration of the Mopar Hemi engine. In 2002, the Gen III Hemi was debuted in the Ram 2500/3500 pickup line, followed by the Ram 1500's in 2003. It boasted 345 hp and 375 lb-ft of torque and was immediately recognized as an excellent engine platform (it has made the "Ward's 10 Best Engine" list six times). By 2005, the 5.7L Hemi was available in pickup trucks as well as the LX-series of Chrysler-family cars.
Some say that the Gen III Hemi, commonly short-handed as the "G3" to help differentiate it from the Gen-III GM motors, is not a "true" Hemi since it doesn't have a traditional hemispherical head design. These people usually eat their own boogers and think that boys shouldn't be allowed to play with dolls. Ignore them, you don't need that negativity in your life...
Much like the GM and Ford counterparts, the Gen III Hemis took advantage of engineering and computer-aided design advancements. As a result, the Gen III retains a traditional push-rod orientation but with significant flow improvements over the previous Gen II V8 engines (such as the Magnum).
In 2009, the 5.7L Hemi received some major internal changes and an even larger use of technology. The block was new, the crank was upgraded, the cylinder heads were better and the cam got a tad more aggressive - all while sporting better power and economy. The 5.7L Ram engine - known as the "Eagle 5.7" was now rated at an honest 390 hp and 407 ft-lb of torque. Some people consider the 2009+ engines to be the "Gen IV Hemi", but this naming convention has not caught on. Most people simply refer to them as the "VVT engines".
The biggest change was the use of VCT - variable cam timing. The ECM can now vary the valve opening to optimize flow throughout the RPM range. The use of MDS - or multi-displacement system technology was continued but improved upon and matched with the VCT for significant gains in economy. It isn't uncommon for swapped rigs to push 18 MPG in Jeeps (when coupled with the Dodge transmissions).
Later Eagle updates also included a "SRV" (short runner valve), which is essentially part of the Hemi "active intake". This valve provides a bypass for incoming air and moves it from the plenum directly to the cylinder heads. The shorter route allows for more power at higher RPMs while allowing the nice long, wide torque curves of a traditional long runner.
What Hemi Should I Swap?
While some older JKU Hemi swaps indeed utilized earlier, non-VVT Hemi swaps, this has all but stopped. The VVT engines make more power, are easier to find, and are cheaper due to availability. There's no compelling reason to use a non-Eagle/VVT Hemi in a JKU swap.
That said, there are some considerations to be made for what platform you got your donor from. The donors are usually broken up into car/SUV, often referred to as the 'LX-platform" motors (not to be confused with LSx), and "truck-VVT" motors. Internally, all the engines are the same. The differences come on the exterior.
The 5.7L truck engines are often easier to find, and many include an 8HP70 if you're considering that swap as well. The truck engines have physically longer front end accessory drives (FEAD). Essentially, the water pump, power steering pump, A/C compressor, etc. all stick out further from the timing cover than car/SUV FEADs do. This means you are unable to run your OEM Jeep fan. You need to either run a manual fan, or go with the common "Camaro fan" (which is thinner profile than the Jeep fans).
LX (car/SUV) engines can reuse your OEM fan. 6.4L engines (from car or truck) must move the air cleaner to the driver side fender due to how the intakes are shaped on both. Any and all engines can be made to work, you may just need some different parts to make it all work together (more on this below).
If anyone has ever spent time on the Wrangler TJ Forum, you may have seen my Gen III Hemi swap info there. I figured since I'm going through the work on my JKU, that it just makes sense to do that here as well. There are plenty of YouTube videos, some done by vendors selling swap parts (such as Jeep Speed Shop, which is who I'm primarily sourcing my part from), and some done by people trying to help others out.
Some worthwhile videos to check out:
JKB Off-Road: https://www.youtube.com/@JKB_OFFROAD_olllllllo
JK Gear and Gadgets: https://www.youtube.com/@JKGearandGadgets
Jeep Speed Shop: https://www.youtube.com/@jeepspeedshop
While I love YouTube videos, and I may even make a few of my own in those instances where I think other videos may fall short, I think there's a lot to be said of having a step-by-step forum post that can be referenced, corrected, and added to as needed. I'll be building this thread out as I go through my swap, where I'll be putting a 5.7L VVT LX Hemi and 8HP70 into my 2008 JKU. I'll have some info about the Hemi swap in My Build Thread, but the bulk of the technical information, references, and more, will be saved here for future easy reference by myself and by anyone else who needs it.
If there's something I glossed over or something you want expanded up, just let me know!
What is a Hemi?
The Gen III Hemi ("gen three", or generation three), is, as the name would suggest, the third iteration of the Mopar Hemi engine. In 2002, the Gen III Hemi was debuted in the Ram 2500/3500 pickup line, followed by the Ram 1500's in 2003. It boasted 345 hp and 375 lb-ft of torque and was immediately recognized as an excellent engine platform (it has made the "Ward's 10 Best Engine" list six times). By 2005, the 5.7L Hemi was available in pickup trucks as well as the LX-series of Chrysler-family cars.
Some say that the Gen III Hemi, commonly short-handed as the "G3" to help differentiate it from the Gen-III GM motors, is not a "true" Hemi since it doesn't have a traditional hemispherical head design. These people usually eat their own boogers and think that boys shouldn't be allowed to play with dolls. Ignore them, you don't need that negativity in your life...
Much like the GM and Ford counterparts, the Gen III Hemis took advantage of engineering and computer-aided design advancements. As a result, the Gen III retains a traditional push-rod orientation but with significant flow improvements over the previous Gen II V8 engines (such as the Magnum).
In 2009, the 5.7L Hemi received some major internal changes and an even larger use of technology. The block was new, the crank was upgraded, the cylinder heads were better and the cam got a tad more aggressive - all while sporting better power and economy. The 5.7L Ram engine - known as the "Eagle 5.7" was now rated at an honest 390 hp and 407 ft-lb of torque. Some people consider the 2009+ engines to be the "Gen IV Hemi", but this naming convention has not caught on. Most people simply refer to them as the "VVT engines".
The biggest change was the use of VCT - variable cam timing. The ECM can now vary the valve opening to optimize flow throughout the RPM range. The use of MDS - or multi-displacement system technology was continued but improved upon and matched with the VCT for significant gains in economy. It isn't uncommon for swapped rigs to push 18 MPG in Jeeps (when coupled with the Dodge transmissions).
Later Eagle updates also included a "SRV" (short runner valve), which is essentially part of the Hemi "active intake". This valve provides a bypass for incoming air and moves it from the plenum directly to the cylinder heads. The shorter route allows for more power at higher RPMs while allowing the nice long, wide torque curves of a traditional long runner.
What Hemi Should I Swap?
While some older JKU Hemi swaps indeed utilized earlier, non-VVT Hemi swaps, this has all but stopped. The VVT engines make more power, are easier to find, and are cheaper due to availability. There's no compelling reason to use a non-Eagle/VVT Hemi in a JKU swap.
That said, there are some considerations to be made for what platform you got your donor from. The donors are usually broken up into car/SUV, often referred to as the 'LX-platform" motors (not to be confused with LSx), and "truck-VVT" motors. Internally, all the engines are the same. The differences come on the exterior.
The 5.7L truck engines are often easier to find, and many include an 8HP70 if you're considering that swap as well. The truck engines have physically longer front end accessory drives (FEAD). Essentially, the water pump, power steering pump, A/C compressor, etc. all stick out further from the timing cover than car/SUV FEADs do. This means you are unable to run your OEM Jeep fan. You need to either run a manual fan, or go with the common "Camaro fan" (which is thinner profile than the Jeep fans).
LX (car/SUV) engines can reuse your OEM fan. 6.4L engines (from car or truck) must move the air cleaner to the driver side fender due to how the intakes are shaped on both. Any and all engines can be made to work, you may just need some different parts to make it all work together (more on this below).
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