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Chevy 5.3 LS vs Hemi 5.7 vvt.

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Old Nov 15, 2012 | 06:08 AM
  #1  
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Default Chevy 5.3 LS -vs- Hemi 5.7 vvt.

Fellow JK'ers, Some may recall my previous thread whereby i described my oil consuming 3.8l engine and various options to fix/replace.

The progression of ideas has lead me to the following choice for my 2010 JK 4dr Sahara auto.
Current mods include: AEV 3½" lift; 4.88 gears and lockers; AEV hood, bumpers, wheels; 35"s; intake & exhaust.

1. AEV in Michigan. For approx $21k have turn key install with 5.7 HEMI & 545RFE 5 speed transmission.
a. Pro – 3 year/36000mi. warrantee on part & labor. they will pay to have fixed locally.
b. Pro - Its a HEMI! but if it matters, more 'correct' swap for the Jeep brand.
c. Pro - expected specs: 360 hp Torque = 390 ft/lb.
d. Pro - new radiator, new exhaust and cats with kit.
e. Pro - they are professional, has thousands of swaps completed.

f. Con - Transmission is only 5 speed, not best opinions out there for this transmission. not optimal for my 4.88's.
g. Con - Expect no improvement with MPG.
h. Con - AEV install supposedly has engine sitting further forward in Jeep, not as 'balanced'

? - not sure, but is the Hemi still a cast iron block? is that good or bad?
? - not sure, AEV disables the 4-cylinder mode of the vvt
2. MOTECH LS swap kits. For approximately $19-20k gets New Chevy 5.3 LS vvt engine with 6180 6 speed transmission. I can have turn key service from corporate in Vegas, Affiliate in AL. or my local shop install with full Kit. Engine has 3/36 warantee. All shops will give me 1 year on labor.
a. Pro – Expected specs: 315 hp 320 ft/lb. torque.
b. Pro - Newer engine design, aluminum block.
c. Pro - smaller than Hemi, supposedly fits in JK easier, keeps weight further behind the front axle.
d. Pro - The Motech setup, gives you 'tap shift' a manual control for transmission. good options for towing and/or trails.
e. Pro - from consumer comments, expects to improve MPG
f. Pro - Apparently great feedback from this transmission in all models it's in.

g. Con - New kit, not that many around
h. Con - Chevy engine in a Chrysler...?
i. Con - Kit does NOT include new radiator, or exhaust only new cats.
j. Con - less HP/Torques than Hemi. (but i'm not racing it, and anything is better than 3.8!)

? - not sure, Motech keeps the 4 cylinder mode in their software.
I'm expecting to keep the Jeep for a long time after i do this. I had my Jeep pretty close to the way i wanted it when the 3.8 began to consume oil @ 39k miles. Jeep is a 2nd vehicle, I wheel 6-8x a year, use for some towing, plan to use on long distance vacations with family; expect to put 12k miles on a year.

I'm really stuck with my decision, i'm hoping the community can help guide me along in the choice. Plan to get this started next month.

Cheers and Ride lots!

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Last edited by ridelots24; Nov 15, 2012 at 07:55 AM.
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Old Nov 15, 2012 | 06:54 AM
  #2  
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LS!!!!!!!! Lighter and i think they sound "mean"!! And i asked about this kit and u can get a new aluminum radiator. Just email them.
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Old Nov 15, 2012 | 07:06 AM
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I would go with the 2.8 liter VM Motori turbo diesel that they put in the overseas Wranglers and used to put in the Liberty's here. I would consider a Cummins 4BT turbo diesel (very loud), or B3 3.3 turbo diesel (not as loud or as powerful).

Given your choices, definitely the 5.3 Vortec; who cares if it's not a Chrysler product? Neither engine was designed to go in a Wrangler anyway. The 5.3 is a solid power plant, makes more than enough hp/torque, and if it sits better in the Jeep, all the better for all kinds of driving and future maintenance.
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Old Nov 15, 2012 | 07:37 AM
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swap in the pentastar.
1. its made for the jeep, less parts you will need to fab to make it work
2. new 5 speed auto tranny is awesome
3. its only like 15% less hp/torque than the ls 5.3
4. better mpg, i get almost 21.5 mpg out of mine
5. im not sure but im willing to bet its lighter than the ls motor, meaning even better weight distribution.

cons
1. not quite as powerful as v8
2. ticking head issue, from what i understand the problem in the casting process of the heads that caused this issue has been addressed
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Old Nov 15, 2012 | 08:20 AM
  #5  
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As long as they can do it and have everything still work right (Cruise control, gauges etc.) Id go LS.

I know you seem to already have made up your mind but have you thought about maybe putting new rings in your current motor? Might be a hell of a lot cheaper and if you really want more power you could always Turbo or Supercharge it for way less money.
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Old Nov 15, 2012 | 08:27 AM
  #6  
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Id vote LS.. Hemi is overdone on this forum
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Old Nov 15, 2012 | 08:37 AM
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I'd go LS all day long! Parts are more readily available and cheaper! Plus the weight reduction!
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Old Nov 15, 2012 | 09:02 AM
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Originally Posted by Rob 12B1P
As long as they can do it and have everything still work right (Cruise control, gauges etc.) Id go LS.

I know you seem to already have made up your mind but have you thought about maybe putting new rings in your current motor? Might be a hell of a lot cheaper and if you really want more power you could always Turbo or Supercharge it for way less money.
I did consider this option. Assuming that Chrysler would void fixing my motor for free, as i've done so many mods.

Local shop quoted me 5k for rebuilding short block w/ better components
Add turbo kit 5k
Add labor to install turbo kit 1k

Agreed, 11k total is less than what i'm defining as my current options..... In my opinion, for the additional money just getting the V8 and lower end torque is worth it for the long haul. Not that i have back up, but feel that longevity of engine is better with V8 vs V6+SC at high rev's to make equivalent power.. Not saying your idea isnt a good one, but thats just how i viewed it.

of course, my wife thinks i'm crazy and should just dump the jeep and renovate our kitchen....... pfft....womeRn's.....

Last edited by ridelots24; Nov 15, 2012 at 09:07 AM.
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Old Nov 15, 2012 | 09:13 AM
  #9  
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Only swap I would do is the 4bt.

Low end grunt aka torque monster
Mpg are up there
More transmission options
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Old Nov 15, 2012 | 09:57 AM
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Be careful not all LS are aluminum blocks, I would verify that up front. It's about a 75-90lb difference. Either way it's a ton light than the all iron hemi, it's more fuel efficient, the trans is better, it's cheaper and there's better aftermarket support.
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