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Thread: Which LS is for you? (Or me?)

  1. #11
    Nothing but a Thing Grubbicon's Avatar
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    Like Thardy said my mom does have a TJ with a 5.3. Its on 37s and the d30/35 but of course she just rides around town in it. Its geared horribly so its a dog. Its in how you use your Jeep. Me personally I know how I drive with my v6s and there is no way I could get away with anything less then tons with my heavy right foot tendencies.

  2. #12
    Old Timer DWiggles's Avatar
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    Awesome thread idea. In for info!
    I've been thinking I want to go with an ls3 (new or low milage >10k) and a 6 speed manual. But we will see what the future brings.

  3. #13
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    After supporting about 200 swaps here is my opinion. I will limit this the Gen IV engines since they are emissions compliant and make the most sense in a JK. I will also assume you are running a 6l80 transmission since it is very strong, adaptive, low friction, low heat , inexpensive and available. The 6l80 has a 4:1 first gear and .6 OD which is key to performance, economy and gearing. Guys with 5 speed Chrysler transmissions think they work great compared to the 4 speeds, then drive a 6l80 and feel the difference.

    With such a low first gear you can run one size taller gear and still launch a heavy JK hard; then cruise 2,000 rpm @ 70 mph getting reasonable fuel economy in the second OD gear.

    There are 3 basic engines to choose from based on performance vs cost, the 5.3, 6.0 and 6.2.

    While a great engine the 5.3 is usually not the best choice for our JK's. The 5.3 is only 1.5 liters larger than a 3.8 and has less torque than the other engines. Torque is what hauls your JK around, up hills, fighting headwinds, high altitudes, etc. The larger displacement engines simply have more torque; this means they are more efficient in heavier JK's.

    Going to Moab @ 70 mph at 7,000 feet fighting a headwind up a hill is a lot of load on the powertrain; especially in a lifted JK with a lot of drag. The 5.3 will hold the speed but it will downshift, it will go open loop into performance enrichment. This means the 5.3 is spinning faster and running richer, approximately 12:1 in OL.

    A 6.0 or 6.2 will hold a higher gear spinning the motor slower, the engine will stay in closed loop running off the O2 sensors with an AF of about 14.2:1. Would be about 14.7:1 but we run alcohol in the fuel so stoich is a bit lower. In the end the larger engine is more efficient in a heavy JK as well as more pleasant to drive without the downshift. A 40" wheel/tire combo can weigh 200 pounds x 4 = 800 pounds so available torque is critical.

    So is the 5.3 useless - no. In a light JK with minimum lift and 32" Rubicon wheels and tires the 5.3 is great and can return 20 mpg on the highway. The key is light and low drag, plastic fenders, bumpers, etc.

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    Last edited by MOTECH; 08-08-2016 at 04:55 AM.

  4. #14
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    When it comes to the 6.0 and 6.2 they will both get the job done, it comes down to performance vs cost. The truck 6.0 is built to haul weight, and it will do it on regular gas (like the 5.3). The 6 liter engine has an iron block and is almost bulletproof. The 6.0 is a great expedition engine because it runs on almost any gas and can be abused. The 6.0 engine is inexpensive and readily available.

    The all aluminum 6.2's are a step up in performance and cost. With high compression heads and all aluminum construction they are designed for performance and turn your JK into a mild muscle car. The 6.2 engines require premium gas, synthetic oil and cost more than the other engines. The flip side is all the 6.2's are over 400 HP and fun to drive.

    Amongst the 6.2's is the truck and passenger car engines. The truck engines have a little more bottom end and less HP while the LS3/L99 have more top end and higher power band. If you drove any 6.2 most of us would think it is enough if not too much HP.
    Last edited by MOTECH; 08-08-2016 at 04:57 AM.

  5. #15
    Knows a Thing or Two Journeyman's Avatar
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    Wow! As usual tons of information. Thanks Motech.

  6. #16
    Nothing but a Thing nmwranglerx's Avatar
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    Every time I read something about these LS engines I get more and more excited about the possibility of putting one in my JKU someday.
    "all roads lead somewhere" -anonymous

  7. #17
    Hooked Big Bad Wolf's Avatar
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    Great thread! And, thank you Motech!

    I know they are both solid, but would the L96 win over the LS3 in terms of reliability and repair costs ? I know the LS3 would be fun to drive but it sounds like the L96 has plenty of power for 40" tires.

    I went to my local GM to price out an LS3, they were very intrigued about my intentions.
    Last edited by Big Bad Wolf; 08-09-2016 at 04:32 AM.

  8. #18
    Hooked caminton's Avatar
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    Quote Originally Posted by Big Bad Wolf View Post
    Great thread! And, thank you Motech!

    I know they are both solid, but would the L96 win over the LS3 in terms of reliability and repair costs ? I know the LS3 would be fun to drive but it sounds like the L96 has plenty of power for 40" tires.

    I went to my local GM to price out an LS3, they were very intrigued about my intentions.
    I'm pretty sure the L96 has more torque. They're "truck" engines (suburbans, tahoes, silverados, escalades, sierras, etc.) vs. the LS3 being the "passenger car" engine (corvettes).
    Reliability, probably higher in the L96. Repair costs, definitely higher in the LS3.
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  9. #19
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    Quote Originally Posted by Big Bad Wolf View Post
    Great thread! And, thank you Motech!

    I know they are both solid, but would the L96 win over the LS3 in terms of reliability and repair costs ? I know the LS3 would be fun to drive but it sounds like the L96 has plenty of power for 40" tires.

    I went to my local GM to price out an LS3, they were very intrigued about my intentions.
    The 6.0 has plenty of power for 40's. The 6.0's are intended for HD trucks so they have a lot of low end torque, similar if not more than the 6.2's off the line. The 6.0's have VVT and the LS3 does not. This means the 6.0 has great bottom end to get you rolling and at about 4,000 rpm the torque flattens out; then the cam phases and you get a second burst of power.

    The truck 6.0's were designed from the ground up to move weight. The lower compression heads, iron block and conservative tuning are meant to make it reliable even when abused or neglected. The 6.0 is designed to run conventional oil and use regular gas keeping operating costs down.

    The LS3 shines if you want performance. The non VVT LS3 runs higher compression, aluminum block and high flowing heads. The LS3 is more power than you need for the average JK IMO. I would not say the LS3 is less reliable but it does require better maintenance. The LS3 uses Dexose synthetic oil and requires premium gas.

    Bottom line is the 6.0 will easily get the job done. The 6.0 is a workhorse engine that is great in expedition vehicles whereas the LS3 is a high performance Vette engine and a lot of fun to drive.

  10. #20
    Hooked Big Bad Wolf's Avatar
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    Thanks Caminton and Motech. I will keep my eyes open for an L96.

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