Which LS is for you? (Or me?)


That dude from Mississippi
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.

Great stuff. I plan on a truck motor, when the time comes.



I'm taking a different approach than most. Its a LC9 that has the DOD removed, a Comp cam installed with a phase limiter. With custom tunes should result in 400HP use reg gas. I'm running 40's, 5.38's and am 6400lbs empty. Hopefully will be installed by the end of the year and I'll report on the results.


New member
Resurection of thread with feedback.

So I thought it might be a good thread to post your experiences with the different LS engines that MoTech supports. As a potential customer still trying to decide all the major details, it would be cool to see real world applications, and to discern the differences between the different versions of the LS engines.

1. Which engine did you go with? (L92, L94, LS3, etc.)

2. Which transmission did you go with? (6L80, 5 speed, 6 speed)

3. What are the big numbers for you? (Horsepower, torque, MPG, speed, accelerations)

4. If you're willing to divulge, what did you pay for your swap? Did you get a used engine or new?

5. Anything else you'd like to add that we should all know.

And if MoTech wants to give feedback for their different options, I'm sure we would all benefit from the answers!

Sorry for the resurection of this old thread but I felt this is a good thread with good questions for future builders. I will give you a short history of this build and then answer the above questions. I started this build with questions for Robbi in late 2010. Found an engine fire 2008 Sahara on a auction site out in Rhode Island that looked like it would be an excellant canidate for a engine transplant thinking this was smarter then buying a perfectly good running one and gutting it. Thoughts on this philosophy later. Background, this is my first jeep, first non-carburated EFI anything build of any kind so a very steep learning curve is involved. So here we go!

1. Went with a LC9 2011 out of a wrecked pickup.

2. Matching 6l80 out of wrecked truck.

3. Motor is suppose to be stock. Salvage yards story was this motor any tranny came out of truck that fell off car carier with only 20 miles on it. Later on story was they didn't know. Did some checking on VIN and it appears it was a take out motor. End result my long term trims would go well over +20% and that sends you into limp mode. Result had jeep dyno tuned because stock perameters wern't working. Dynoed at 292 hp on 87 octane and 0 timing. Lessons on this whole ordeal later.

4. This was I think number 12 or 14 for Motech's LS kit so things were in a developement mode yet. I had $4500 into motor and transmission with shipping. The kit plus any other supplies came to around another $2000 so grand total under $7000. Robbi gave me a break on a lot of stuff since the agreement was to help put together instructions for him. Everything was a learning in progress at this time for myself and with Robbi and the builders kit. This wasn't for the faint of heart at first and consisted of a considerable amount of re-wiring and wiring of the jeep harness's and such. The Gen III kits are getting pretty much plug and play!

5. Now for the lessons. Buying some one elses dream not running and needing considerable amounts of rehab just to get it back to a useable state and doing this for the first time not a good idea! It forced me to get real personal with this jeep and makes it hard to sepperate from if needed. I bought it at auction and shipped to my home for a total of just under $5000. Total to get everything back to transplant state about $13000 so built jeep to V8 for around $20000! Time spent doing this over 4 months priceless! In hindsight I would rather of bought a totaled flooded vehicle with working CanBus then a fire. Grounding issues and getting paint to stick after being burnt or just panting stuff in todays techology in general is not easy without experience with these products!
Number two I should of listened more closely what Robbi was telling me! He strongly suggested I buy a 6.2 which I could of done for a $1000 more from the same salvage yard! But story was this one also came from said donor fell off car carrier! Would I have had same tunning issue I will never know. With that said I still dont have a reason why this 5.3 with all matching numbers is putting out close to 30 hp more then it should be. On premium gas no ethanol it is a little screaming fool! But it was a considerable head ache till tunning problem was resolved! It caused me to upgrade the LS harness to Robbi's gen II harness and electronics because of 2138 code limp mode problems and what we thought were harness problems when it was tunning! The 2138 was mostly a ground issue with the fly by wire between the throttle body and the gas peddle. That is why they use genuine GM harness's now instead of hand built. These electronics are getting more and more sensitive with multiple senesors watching inputs and outputs for safety that any little connection loss or bad grounding results in failures or random limp mode scenarios. I had multiple issues going on so to say the least it was frustrating! But with little understanding at the time it fired up on the first try! Reason for going with 6.2 would be my setup is at the edge for what you gain from price compared to what you gain from stepping up. I get a cosistant 12 mpg mixed driving and on the interstate with 35 Nitto tires and 4:10 gears it shifts a lot at 75. Now a Gen V LS 5.3 would be better since it makes great torque at lower rpm's then the Gen IV does hence the shifting down more. My thought was if I did the 6.2 my running gear wouldn't last. It came with 5:13 gears and yes with those it would not have lasted long. This leads to third lesson.
Number three I should have listened to this group and especially Eddie when it came down to running gear, geometry and lifts. Yes I learned a lot doing it my way but at a cost. First I should of not stuck the stuff I did into the 30 front axle. Trussing it and putting RCV axles in was a waste of money. Yes it still live's but in hindsight I could of did a Ultimate 44 for the time and money spent with re-gearing and added axles and trussing. Second by doing things my way and learning by doing stuff multiple times is not very efficient! Listen and learn! On this forum and other sites there is a lot to be learned and taken into account for. Take addvice and do your research! It will save you time and money in the long run. Don't re-invent the wheel! Set objectives or goals and then figure out the best path to get there!
Lastly I have an example of how nice a system the LS is. Last Thursday night I am driving home after picking up my son from football practice. At a stop light the engine stutters for a second but keeps running. My son smells gas which makes sense after the fact it went into a limp mode. Now my wrench light did not come on but I could tell something was up. On my Aeroforce gauge I had miles per gallon as one of the displays. It was going from 20 something mpg to 2,000 something mpg back and forth. The code I was getting was a p0102 MAF mass airflow sensor error. While moving I reset the code and instantly the motor shut off. Now normally one would limp home and scan for codes and find the error code. With the guage I can do this on the fly but this could of led to me not being able to limp home. Luckily it restarted after a few trys. When this MAF sensor failed I lost my CanBus which is how the ECM talks to everything. By resetting the code the ECM lost communications to everything else because I did not know the MAF sensor had basically opened up and broke the communications path. Point being should of drove home in limp mode then trouble shot. This sensor was only a little over a year old and failed. It was replaced before I had it dyno tuned when shot gunning before replacing engine harness. Luckily I had original Robbi sent with Gen I kit and fired right up. I have been having some wierd CanBus issues even on the jeep side with my radio not coming up on startup. The two systems are tied together now with the Motech module or basically a protocol converter between the LS CanBus and Jeep CanBus. This is how things can be made to work between the two systems. I'm thinking this MAF sensor could have been the culprite till it finally died. The LS has several limp modes and on occasion it just didn't seem to run right so time will tell if these last gremlins are gone.
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