TJ Jeep Hemi Conversion

[unlimitedrubicon]

I am currently early in the discovery and planning stages, but I am looking at swapping in a 5.7, or ideally, 6.1 Hemi into a 2005 Jeep Rubicon. From what I am seeing, the recommended engines are from 2003-2008, and the recommended transmission is the 545RFE. Initially, I am finding better options with the car engine, but I would need to source the transmission from a 4wd truck or SUV. Also, the company that seems to be the crowd favorite for the wiring harness favors the PCM from a 2005 truck to keep it compatible with my existing gauge cluster since it is the older PCI bus. What issues, if any, should I expect by using different donor vehicles for the engine and transmission? Also, would I be able to update the VIN with this combination to maintain emissions compliance?

[84lx]

I don't know where you're from, but where I am in NC, there's no way anything that requires an emissions inspection can pass with a non-factory engine swapped in. During the inspection you have to input engine size, and plug in an OBDII device supplied by the state. I imagine there is data gathered that would tattle on you, even if you put in the factory engine size. Maybe it would work. Never tried, not going to.

The mixing and matching of parts isn't an issue as long as you have the right stuff to mate it all up. Sensors may have different plugs, going to need to do research on what flexplate you'll need, etc. But it sounds like the emissions thing is going to be an issue for you. Talk to someone local to you.

[Wjjeepman34]

As long as both engine and Trans are NGC3 (or at least that's what I think the 05's are), you could run the truck (545rfe) or the car (nag1) transmission. Depends on what you're trying to do with it at the end of the day. The 545rfe is a stout Trans, with 2 overdrive gears (.75, .67), somewhat because of the nature of a lower geared (numerically higher) differential gear, i.e. 3.73. 1&2(and technically 2nd prime, yes it has 2 2d gears 1 for upshifting pattern(1.67), one for downshifting into 2nd while WOT(1.5), and basically a 6xRFE Trans just uses both during normal upshifting) are underdriven, 3rd is 1:1. The nag1/wa580 has just one overdrive gear, that is lower (numerically higher, iirc its like a .83, but not 100% sure) than even the 1st overdrive gear of the 545.
So, depending on your diff gearset, tire size, and overall plans with the jeep, you may prefer one over the other. The Nag1 is just as strong as the 545.

The one thing I'm not so familiar with, is mating up a tcase to the nag1. I assume you'll run the tj 231, and it'll probably bolt up to the nag1, but I can't say for sure. While 100% you can bolt a 231 to the 545, I have that setup in my 2004 WJ (grand cherokee), that came with a full time (awd) tcase originally.

[chasmosis1]

I have done this conversion to a YJ and I can help with some info. The 231J will bolt directly to a (5)45RFE. The 2005 NGC3 ECM is preferred and will run it perfectly fine, however you will find that there really isn't a ton of support for this ECM if you decide to add any performance parts. I can tell you however that a stock Hemi in the short wheel base vehicle is a lot of fun in itself. You will have to choose what accessories you will be running as the car intake will not fit the truck motor without changing the timing cover as well. The stock truck exhaust manifolds fit well in the Jeep chassis. You will need to install a SYE into the transfer case and have a CV shaft built for the rear driveline. If you haven't already replaced it than you'll be quickly finding out how weak the Dana 35 is in the rear of the Jeep. I used a "Hot Rod Harness" as well as Dakota Digital boxes to make all the gauges work in the YJ. I envy you as you are able to buy the mounts to allow you to bolt the Hemi into your TJ, I had to design and fabricate everything from front to back.