392 V8 Engine Swap is In and Running!! (2023 Gladiator Mojave)

I have the 392 in and running. Still need to clear some DTC's. But for the most part it is fully functional. This is pretty much an "OEM" swap. All the parts are orderable from Jeep. For the programming you need to go to someone other than Jeep to get done. In my opinion, the Gladiator was made to do this. For example the windshield washer bottle on the 392 Wrangler's, is deep down inside the drivers side wheel well. Between the firewall and drivers side inner fender. The studs, holes and cage nuts to put it there are already installed. Unless the diesel Gladiators used the same washer bottle setup? Only the 392 Wrangler's would use that position. I kept the MP1622, Select Trac transfer case. So unlike the 392 Wrangler's, I CAN do 2H!! I suspect epic burns will ensue LOL! I kept the Mojave Orange accent color on the "valve covers" and 392 hood emblems. These too were orderable from a Jeep licensed supplier! I am kind of torn on installing the Hydro Guide. It will bolt up but isn't a Mojave "thing"!?

Did you do the swap yourself?

Ryan, I did the labor and parts ordering. The programming I had to use someone to do that. This isn't an AMW or RubiTrux "kit". Which as far as I know, they don't offer. It really is for the most part OEM.

Well that's cool, what special parts or programming did you need and where did you source it?

tcabece said:

Ryan, I did the labor and parts ordering. The programming I had to use someone to do that. This isn't an AMW or RubiTrux "kit". Which as far as I know, they don't offer. It really is for the most part OEM.

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Nice!

Do you happen to have a parts list?

Did everything bolt in, or did you have to cut/weld/fab anything?

Motor mounts for example, are they from a 392 Wrangler and did they bolt right in?

J.R: You'll need your original BCM. However this is one of the only modules that you can get a dealer to copy. So before I pulled anything out of my Gladiator I had the dealer install and program a new BCM. The BCM is central to the logic flow of the whole system and most importantly it has the IMMO codes. You'll then need to source a used ECM from a 392 Wrangler. These are not difficult to find (LKQ) it seems like lots of owner wreck these things! LOL. Tom's 4x4 Superstore out of Chattanooga, TN did the programming. New 392 ECM's come blank, unless you have a friend who has a 392 Wrangler. I suppose you could then get a dealer to "replace" their original ECM with a new one??
One issue, is that the 392 Wrangler's only came with the GPEC2A ECM. JL's and JT's up until 2020 maybe early 21 all used GPEC2A, ECMs. Later years switched to the GPEC5. As far as I know, no one is programming the GPEC5's, as of today. I have a 2023 Mojave manual transmission and the manual transmission JL/JT's kept the GPEC2A until 2023. When Jeep dropped the Manual option. If you have a GPEC5 Gladiator, you'll have to do some research to see if you can swap it out to a GPEC2A. This very critical because there are lots of other modules (ABS, DTCM, RF-Hub, Airbag etc...) that are all dependent on the modules talking together. My guess is the GPEC5 systems have newer code than GPEC2A systems. They are probably not backward compatible??

Interesting, I would imagine the 2026 392's will use the newer architecture.

Wheelin98TJ said:

Nice!

Do you happen to have a parts list?

Did everything bolt in, or did you have to cut/weld/fab anything?

Motor mounts for example, are they from a 392 Wrangler and did they bolt right in?

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Ryan: I'll have to work up a parts list and get it over to you. Everything, except the exhaust is available from Jeep. The motor mounts, really the frame perches. The welded on parts of the frame that the motor mounts bolt too. Are different for the 392. I did purchase these from Jeep. These are 4 pieces each side. Because the factory jig that locates these isn't available. You'd have to hang your engine and transmission and then figure out where they weld too. So yes you have to cut off the 3.6L/2.0L/3.0L perches and weld on new ones. Tom's 4x4 Superstore out of Chattanooga TN (they did my programming) make a one piece self locating perch(s) LF/RT that I used. These are is a lot easier to install. The big issue will be your ECM. You'll need a 392 ECM and those are only GPEC2A. Even if you have a GPEC2A Gladiator 20/21 (All) 20-23 (Manual Transmission). You'll still need a 392 GPEC2A ECM. This isn't an issue. The problem is most Gladiators since 2021 have the GPEC5 ECM. You'll have to do some research regarding backward compatibility. There are a whole host of other modules (ABS, DTCM, RF-Hub etc..). I suspect that on a GPEC5 system they have newer software than a GPEC2A system?

Jrgunn5150 said:

Interesting, I would imagine the 2026 392's will use the newer architecture.

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J.R. Your right, as for the GPEC5 programming it is much more difficult. I understand the need for security and intellectual property rights. But I also feel that somehow "the right to repair" is getting trampled on here! LOL

Awesome job Tim!!! Is there a 392 specific radiator/fan for cooling? How hot does it run?

Very nice! I like leaving the accents on under the hood! Guesstimate on what in ran you to do all this yourself?

jmr said:

Awesome job Tim!!! Is there a 392 specific radiator/fan for cooling? How hot does it run?

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Jim: Actually the 3.6L radiator is the same. You can buy a 392 radiator, different p/n. But it is the same. I heard/read somewhere that because the 3.6L has a single exhaust "port" per head. The "exhaust" manifold is effectively water cooled. The heat load for a 3.6L is similar to a 6.4L. The 6.4L have the traditional air cooled cast iron exhaust manifold. I did buy a new cooling module which came with the radiator, condenser and transmission cooler. Only because I had a manual transmission and didn't have the trans cooler. You will need to purchase the radiator "bottle". The radiator fill bottle on the firewall, by the brake booster. As for the fan if you have the tow package, which has the 850 watt fan. It is the same as the 392 fan. My 392 runs fine, cool even but that's probably our Colorado winters! LOL. I will tell you that "burping" the cooling system on a hemi is nearly impossible. Vacuum filling them is the only sure way to get out any air bubbles!

Hemy5587 said:

Very nice! I like leaving the accents on under the hood! Guesstimate on what in ran you to do all this yourself?

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Hemy: I'd say half of what AMW wants. They run about $40k, so $20k savings. This was using a used 392 and 8HP75 trans (and MP3022 transfer case) out of a wrecked Wrangler. These are easy to find (LKQ/EBAY) seems like the owners wreck these at a prodigious rate!! LOL The Mojave's and the 392 Wranglers share a lot of the same parts. Specifically the front and rear DANA 44 differentials/axels. The Mojave front axel uses universal "knuckles" vs the 392 Wranglers that have CV joints for their "knuckles". The front coil springs for the Mojave are the same part number as the 392 Wranglers.

Great job!
So was your 3.6L still good?
What drove you to do the swap?

RougeShot12er said:

Great job!
So was your 3.6L still good?
What drove you to do the swap?

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RougeShot: 3.6L was/is fine. I really had no complaints, the Pentastar is a very capable engine. As for the Hemi, it was really something I just wanted to do. Now that it's completed (or nearly), I am super happy I did do it. I still miss my manual transmission. Maybe a Getrag 238 in the future? But a 20 year old transmission faces some serious software issues with today's code!