General Tech Motor swap vs forced induction

We have done more than enough LS swaps into Jeeps to know what it costs and the work involved, In my opinion my favorite power adder for the 4.0 is the sprintex supercharger kit. It will honestly rival any junkyard 5.3 LS swap, you can do it in a full day and like has been mentioned in here before it is fully reversible in the same amount of time it took you to install it.
 
Sorry I'm late to the game. An LS swap is sweet. A whole lot of fun with lots of smiles per gallon. When I first did mine, I ran my AX15 behind my 5.3. It ripped and I consistently averaged 18-20 mpg with 4.56s and 35s. When I went to 37s, 60s but still with 4.56s, it would do 16-18 mpg usually. I "justified" my swap by saying it would pay for itself in fuel. Turns out you can justify anything to yourself. It was total crap though. I've never run enough fuel through my Jeep to pay for that. I did it "cheap" by doing everything I could for myself and doing a bunch of horsetrading and part flipping. I ended up dropping just shy of $7k. The motor was only $850 of that. The motor is the cheap part. The exhaust, electrical and 9000 other parts you need to buy that add up and nickel and dime you to death.

When I cut my Jeep up and stretched it and such, I also swapped in an automagic trans in the form of a 4L80 and also a Hero transfer case. I did commute it to work quite a bit from Sandy to Lehi, and it only averaged about 13 mpg. I blame that on the 4L80 being such a power sink (rumor has it 40hp alone is required to run the pump) and a gear driven t-case will never be as efficient at transferring power as a 231 or 241. Fact of life. Interestingly enough, turning 40s didn't hurt fuel economy at all....

Lots of good points in here though. And there is a lot to be said for keeping a Jeep "stock". Makes it easier to find parts. And if you do an LS swap, it is an emissions nightmare. Possible. But it is a nightmare.

Mouse said:
With an iron block LS, all of the accessories is right about 100 lbs lighter than the 4.0L with accessories. LS swaps vary in cost depending on how you get the engine/trans and what shape they are in. I know a couple of people who bought complete vehicles, stole the engine, trans, computer, etc., then parted the vehicle out and got all of their money back that they invested in the donor - they actually made money getting the engine & trans they wanted. The LS swap is definitely more work as well.
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I've been busting this myth every chance I get. The internet is full of lies. Haha I had heard this and been preached to while I was researching the swap, in fact I think it is even on Novak's website. But a fully dressed iron block LS and a fully dressed 4.0 to not tip the scales like people think. The 4.0 is about 130# lighter than a 5.3. I think you might be almost an even swap pound for pound with an aluminum block LS. But even that is probably slightly heavier than a 4.0. I used to believe this, but had the opportunity to put each engine on a pallet scale. My jaw hit the floor with the results.
 
Component-per-component wise it's easy to compare, but that doesn't really matter as every swap is different. I'll be sure to get numbers when the opportunities shows itself. I have seen coilover spring rates need to be changed (lighter) on a buddy's CJ5 when he made the swap, but that was going from a 4.2L to a LQ4/TH400. The effort to weigh complete drivetrains is not something I would expect many to be able to do. I'd be interested in the combinations you weighed and what the totals were - nice to see some independent data.
 
Mouse said:
Component-per-component wise it's easy to compare, but that doesn't really matter as every swap is different. I'll be sure to get numbers when the opportunities shows itself. I have seen coilover spring rates need to be changed (lighter) on a buddy's CJ5 when he made the swap, but that was going from a 4.2L to a LQ4/TH400. The effort to weigh complete drivetrains is not something I would expect many to be able to do. I'd be interested in the combinations you weighed and what the totals were - nice to see some independent data.
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I didn't weigh complete drivetrains, only fully dressed engines (intake manifold, all accessories, no flywheel/flexplate). I have exact values somewhere in my files, but I remember the 5.3 was close to 530 lbs and the 4.0 was right around 400. In my case, the front of my jeep sagged close to an inch and I had around 150 lbs more on my front axle and close to the same as before on my rear axle.
 
I have researched the V8 swap EXTENSIVELY. For me, getting rid of the gutless puke of a 150hp engine in an LJ with lots of extra weight and the craptastic mini van trans is going to happen one day, likely when the trans gives up. I looked at the LS swaps a lot but lately the Hemi swaps have caught my eye. Having never done either, it seems from what I have read that the Hemi is an easier swap. The computers play nicer with each other and the 5.7 Hemi's seem to be cheaper. Anyone have any experience with a 5.7 hemi swap? I know Nate built a couple but haven't seen him on RME in a while.
 
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Getting computers to play nicely only matters if you want to keep your stock gauges. Novak (and maybe others) makes a converter box that turns GM signals into Jeep signals. So you keep the jeep computer in place and it runs the dash thinking the whole time that it still has the Jeep motor in it. You then mount the GM computer somewhere and it takes care of everything else. It's actually pretty simple.
I'm not positive but I think I remember the LS series being a much smaller package than the Hemi's, and Fords for sure. Engine bay space is at a premium so the smaller the engine the more you have room for links, driveshaft etc.
 
I've driven a nice AEV LJ with a hemi conversion. It had a ton of torque and sounded great. I'm not sure a hemi swap would be cheaper than an LS. Parts for the hemi motor will be more expensive, so I guess if the plan is too keep the drivetrain as OEM as possible, the Hemi has a chance to compete. LS parts, aftermarket or just replacement are more plentiful and cheaper when I've compared prices (custom oil pans, headers, etc.).
 
All good info Unstuck. I have researched the Novak box and would likely go that way if I go the LS route. I thought their kits seemed way overpriced so it's good to hear you confirm that.

From what I have read, Hemi saves money on a few of the nickle and dime you items. The trans bolts right to the T case with no adapter and no tail shaft conversion needed like the LS/4l60. From my interweb searches the Grand Cherokee fits with stock oil pan and exhaust manifolds so all that saves some money too.

I am not a chevy or mopar fan so i have no loyalty to either platform. The LS aftermarket is 10x the hemi but I don't need anything more than double the HP and torque that you get going from a 4.0 to a 5.7 hemi in stock form. Really you go from 150hp to 330hp. So a stock Hemi would be more than enough.

I haven't decided which way to go, it would be great to hear some real world experiences from both sides.
 
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Now that I think about it, I may have a few parts from Novak if you decide to go LS. I'll look and see, but I'd love to get rid of them.
 
I’d assume the 4L60E is still 27 spline output? I’d just swap to a GM IFS 241 to get the driver drop? Is there a reason you need to use the Jeep tcase with the LS motor and GM transmission? That would surely save a few $

Didn’t the 231 come in S10 trucks? That should bolt to a 700
 
There are a few different ways of going about the t-case. As I recall, the stock 4l60e adapter is LONG and a 241 is pretty long as well. So not such a good fit in a TJ. Depending on what adapter you use and your t-case, you either replace the tail shaft in the transmission, slide on an adapter to the stock tail shaft, or cut the stock tail shaft short. There are stock 23 and 27 spline 231's and it's pretty simple to change out that input shaft to get what you need. Personally I wouldn't want to run a 231 behind an LS, but I'm not real knowledgeable with the chain driven t-cases. If your 231 is all stock then it will cost a fair amount to make it work behind a 4l60. Spend a bit more and get an Atlas.
 
UNSTUCK said:
There are a few different ways of going about the t-case. As I recall, the stock 4l60e adapter is LONG and a 241 is pretty long as well. So not such a good fit in a TJ. Depending on what adapter you use and your t-case, you either replace the tail shaft in the transmission, slide on an adapter to the stock tail shaft, or cut the stock tail shaft short. There are stock 23 and 27 spline 231's and it's pretty simple to change out that input shaft to get what you need. Personally I wouldn't want to run a 231 behind an LS, but I'm not real knowledgeable with the chain driven t-cases. If your 231 is all stock then it will cost a fair amount to make it work behind a 4l60. Spend a bit more and get an Atlas.
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I’m in the Atlas camp if you need to do anymore than $5-700 worth of work to the tcase. Less than that, I’d consider making the case I had work. More $ than that, buy once, cry once as Kurt is known to say.
 
This is where I am totally uneducated. I've got a Rubi lj with the 241. I have a little more length du to it being an lj but saving the $600 for the adapter and tail shaft plus labor sound fantastic. Do you know what gearing ifs 241s came with or if you can swap the 4:1 from a Rubi tcase?
 
glockman said:
This is where I am totally uneducated. I've got a Rubi lj with the 241. I have a little more length du to it being an lj but saving the $600 for the adapter and tail shaft plus labor sound fantastic. Do you know what gearing ifs 241s came with or if you can swap the 4:1 from a Rubi tcase?
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I bet you could swap the 241 input shaft from a Chev case and you’d be good to go? (I swapped a Chev 241 input into a Dodge 241 case and it worked fine. Used the GM adapter). I know nothing about the Jeep case so this may not work? Be worth your time to give it a shot by buying a $200-100 GM t case? Maybe your 241 4:1 gears would swap to the Chev case?
 
glockman said:
This is where I am totally uneducated. I've got a Rubi lj with the 241. I have a little more length du to it being an lj but saving the $600 for the adapter and tail shaft plus labor sound fantastic. Do you know what gearing ifs 241s came with or if you can swap the 4:1 from a Rubi tcase?
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241OR cases have a unique input gear. No other spline count exists. If you want to keep the rubi case, you need to get an adapter of some kind that replaces the output shaft on the trans. However, if you are going to a V8 and a 4L60, in my opinion, you don't need 4:1. Sell that baby for $1500 and get a 241 from the chev and get a JB conversions super short SYE.
 
RockChucker said:
241OR cases have a unique input gear. No other spline count exists. If you want to keep the rubi case, you need to get an adapter of some kind that replaces the output shaft on the trans. However, if you are going to a V8 and a 4L60, in my opinion, you don't need 4:1. Sell that baby for $1500 and get a 241 from the chev and get a JB conversions super short SYE.
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I thinking sell it for $1500 to go towards an atlas and save the adapter cost.
 
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