Essentially, the guy is from Corpus Christie, TX and paid JSS out of California to do the Hemi conversion. It was an earlier install and the computer programming apparently sucked. This is per Todd who owns JSS. After almost 3 years of different computers and the owner not liking how warm the Hemi's like to run he decided to go to an LS. The non-VVT Hemi's are the hardest to keep cool in the JK. It would be fine while driving but climb as high as 230deg while crawling or sitting at idle. JSS was still playing around with different mechanical fan setups and the software was also to blame. The latest computer was given to the owner after he had already delivered the Jeep to MoTech for the LS.
Talking with Robbi from MoTech the Jeep ran and drove very well with that new computer, and its the same computer programming JSS currently uses. It did however like to get warm at idle or while crawling. Robbi blames the mechanical fan, location of the engine in the engine compartment, and lack of any kind of fan shroud. He is very confident that I'll be able to get the swap done and running very well if I get the engine located better and run an electric fan with a proper shroud. The owner of the JK was a 75yr old man with no ability to really mess with that kind of stuff, nor the patience for it. He finally got to a point where he just wanted the Jeep to be "right" and Robbi was able to do that with the LS swap. The 5.3 and 6L80E run a lot cooler stock and fit in the JK a bit better. They're also more efficient and that 6L80 really allows you ti make use of every bit of the power the 5.3L makes.
The engine and trans right now have 20,000 miles on them and both Robbi (who is against Hemi's and was paid to do the LS swap) and Todd (who did the Hemi swap and thinks they're overall better than LS swaps) agree that they run really well and will work great. Robbi has some theories on making it run cooler and I agree with some of them, although I don't agree that it absolutely has to have an electric fan. JSS has a new fan shroud and a different fan they use now, Todd is very confident that with them the overheating issues are over with.
I've read about people having troubles keeping the 5.7's cool no matter if Jeep Speed Shop, Burnsville Offroad/Dakota Customs, or AEV did the swap. I talked with the guys who used to do Hemi swaps at Pollard Jeep (Boulder Jeep dealership) and they said what they eventually figured out was the factory electric fan from the 3.6L JK's work very well and draw more cfm than the electric fan from the 3.8L JK.
Here is my take on it:
The guy was frustrated and I would be too, he dropped 13K$ on a Hemi swap and it wasn't working right or as expected. JSS was helping him but it takes a while to get things perfect, especially on the software side and from halfway across the country. During this frustration he got to drive an LS Jeep and was really impressed, he had the money, so he made the move. He never did drive it with the final computer in it, he wasn't interested at that point either according to Robbi who was willing to try and sort out the Hemi for him and save the guy some coin. By that time the guy wanted and LS, end of story.
Software issues aside not having a fan shroud with a mechanical fan is a huge problem. Electric fans need them too but as they generally mount very close to the radiator they can get by w/o. A mechanical fan sits back from the radiator, not having a shroud means the fan is drawing air from around the radiator and not through it. This is especially the case when your not moving at a speed sufficient to force air through the radiator on its own, so while sitting at idle and crawling on the trail.
The computer I'm getting is the newest one and Todd will be rewriting it for my VIN. I will also be getting his new fan shroud and mechanical fan setup. Between that and the upgraded radiator that it comes with I'm confident it'll run fine and maintain tolerable temps on the trail. If it does get too warm for comfort then I'll make some changes.
I'm getting this setup for pretty damn cheap, as in I'm looking to be into this swap for about 4G's total running and driving. I've also been a mechanic my entire adult life, I am very confident I can make it work and work well. Worst case scenario I might have to go with different programming and a different radiator/fan setup. At about 4G's I've got a long time before I get to where it would've been cheaper to start from scratch with a salvaged engine/trans and fresh install kit. I was figuring 9-10G's to do the LS or Hemi swap, so I'm going to into it for a lot less.
Neither Robbi or Todd think I'll have any issues anyways. Robbi thinks I should go with an electric fan and different radiator, Todd thinks I'll be fine with their new shroud and fan setup. I'm going to try it Todd's way first and if it doesn't work out then I'm going to contact Dakota Customs and get their radiator. I'll combine it with a 3.6L JK fan and see how that does.
As for engine mounting location, JSS and AEV both put the engine in the exact same spot. BOR/Dakota Customs mounts the engine farther back and lower in the frame. The nice thing about that is the weight is lower and more centered, also there is some airflow advantages that way to help with cooling. The drawback is you're modifying the firewall and your driveshafts will need to be changed. There is also no off the shelf engine skid plates out there for it.
Mounting it like JSS and AEV do there is no need to modify the firewall and the stock driveshafts are retained. I can replace my engine skid with a Hemi one from TNT that'll work perfectly with the rest of the aluminum belly system I already have. An added benefit is the guys from Pollard, Trail Jeep, and Northridge are all here locally and always used the AEV installs. Running a similar setup means it'll be familiar to them if I need their help after the swap.
