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392 Hemi NAG1 or 6.2 LT1 10L80

  • 392 (6.4) Hemi SRT with NAG1 (WA580)

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  • 6.2 LT1 with 10L80

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Discussion Starter #1 (Edited)
Just curious what the average JK'r would rather have: 6.4 (392) Hemi SRT V8 mated to their NAG1 (WA580) or 6.2 LT1 with 10L80?

I am back in a JKUR (Recon) and have the torque/hp bug. I have done my research and am trying to compare apples-to-apples turnkey swap-wise; prices are very close/high (Rubi-Trux vs MoTech).

Would probably just get an L96 6.0 6L80 from MoTech, but I want to stay EPA emissions legal in as many states as possible (HD engine in a half-ton etc) because I might move to an emissions strict state like Colorado and want the ability to sell to it in as many states as possible way down the road. The 6.4 Hemi offers the simplicity of the iron block without all the CVVT, Direct Injection, AFM (point of failure). The LT1 is lighter and has the superior transmission (10L80). 6.4 also makes more power stock and will probably leave the engine stock for the most part.

Thanks in advance for your votes and comments.
 

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Doc,
I had the 6.4 Hemi and it worked great for the 36K miles that I owned it. I like LS engines better but this worked out at the time. Once you drive a V8 Wrangler you'll be hooked. Colorado emissions SUCK & really you're at the discretion of the referee on passing or not even if the Jeep is all legal equipment wise.
 
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Discussion Starter #4
Thanks ScubaTech,

Initially it looked like the 392 Hemi iron block is by far the simpler engine and more likely to be reliable, however, I keep finding stories of lifter/cam failures similar to GM Gen IV AFM collapsed lifters. Makes me wary of the Hemi, though I am not stoked about the Direct Injection, Continuous Variable Valve Timing, and Active Fuel Management on the GM Gen V engines either.

I am a fan of Robbie's (MoTech), but I do like the simple interoperability of FCA component communicating with other FCA components and part of this thread is just to find out which combination will be more sought after whenever I sell it and move on. Right now the 392 looks like it is more desirable, just concerned about reliability.

Glas to see the 6.4 Hemi worked well for ya!
 

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Colorado Emissions depends on the county...

I wouldnt get the 10 speed. This is a pure hunch but Im betting it would shift way too much while offroading. Just because it has more gears doesnt mean its better. It just means that the trans shifts more often to keep the engine in the most efficient power band. Considering these motors actually have decently broad power bands, there is no need for a 10 speed unless you are trying to squeeze out one extra mpg.

6.4 with a 6 speed or 6.2 LS non direct injection would be my choice. LS allows for more aftermarket support if that bug you caught really starts itching.
 

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Discussion Starter #6
I prefer port injection in this application. Have heard great and terrible things about the 10L80. Gear ratios are supposed to be great and shifting seamless according to MoTech YouTubes, however, quite a few Tahoe/Silverado/etc owners had bad shaking from 10L80, not sure if it was ever sorted?

Reason I am comparing with Gen V (LT) engines is because if the years and vehicle types used-in. Allegedly need to use same model year or newer engine (2017) and same class vehicle (half-ton) to meet most of the strict conversion parameters.

If I knew I would own forever and emissions/compliance was no issue, would probably do 6.0 L96 (iron block) with 6L80 and be done with it.
 

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Trick question. The answer is none of the above.

392 w. Getrag 238 FTMFW!

Sent from my LG-H918 using Tapatalk
 

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Thanks ScubaTech,

Initially it looked like the 392 Hemi iron block is by far the simpler engine and more likely to be reliable, however, I keep finding stories of lifter/cam failures similar to GM Gen IV AFM collapsed lifters. Makes me wary of the Hemi, though I am not stoked about the Direct Injection, Continuous Variable Valve Timing, and Active Fuel Management on the GM Gen V engines either.

I am a fan of Robbie's (MoTech), but I do like the simple interoperability of FCA component communicating with other FCA components and part of this thread is just to find out which combination will be more sought after whenever I sell it and move on. Right now the 392 looks like it is more desirable, just concerned about reliability.

Glas to see the 6.4 Hemi worked well for ya!
Doc,

Most of the cam issues were early 5.7 Liter. That 6.4 has all the goodies in it. I used to have a spec sheet I found on All Par. Mine was a crate engine, no MODs but did have VVT. The integration was like a factory set up. I had a couple glitches in the first 1K and the rest of the time it was flawless. The 5 speed auto worked good off road as all the gears from L1 through high range were in succession so they never overlapped like some trannies.

I rented a Jeep last fall for Moab and it had the 8 speed with turbo 4 and it worked surprisingly well.
 

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Discussion Starter #10
Thanks again Scubatech, makes me feel better about the 392 with exception of damn-near $30k turnkey cost 😅
 

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Thanks again Scubatech, makes me feel better about the 392 with exception of damn-near $30k turnkey cost 😅
Doc,

You can source that engine on the internet. I found several places that had a good inventory. The price went from $ 12500. to $6600! Had I not found this I would have had to settle for a 5.7 Liter. So for $ 600. more I got the 6.4 Liter. There are a lot more engines available now than there were 6 years ago. Kits are similar in cost & install price should be the same.
 

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I would go with the gen 5 if it was me. I’m in Colorado with a 6.0 6l80 and absolutely love it. It has been super reliable with no issues.
 
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