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3.7L swap

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v6 swap
16K views 20 replies 13 participants last post by  Oldbear 
#1 ·
I just got my first real jeep last week. I've owned a 2003 Liberty Sport 3.7L and a 2000 Grand Cherokee Laredo with the 4.0L but now I have a 2006 TJ 2.4L 6 speed and it's low mileage so nothing major planned right now but the power is definitely lacking. Given some catastrophic event destroys my motor has anyone done a swap to the 3.7L? I think I prefer it over the 4.0 at this point just for refinement and power. I'm not particularly interested in a v8 swap and I don't feel like the forced induction 2.4 turbo or a supercharger are the way I want to go for longevity. I would like to keep my 6 speed transmission either the stock one I have or a different unit built to handle the additional hp and torque.
 
#2 ·
The reality is that even if you convert it to a 3.7L, you are risking the value of the TJ if you ever decide to sell it. Most potential buyers will avoid conversions in fear of not knowing what they are getting into.

So lets say your TJ is worth $10K now, you convert to a 3.7L for $5000. If you sell it in a few years, ya can probably sell it for $6K. But if money is no object and you have the knowledge and tools for a conversion, and love figuring out and overcoming challenges... it could be a fun project.
 
#3 ·
Unless you're going high performance conversion on a rig you otherwise love (think duramax!) you're really better off sourcing a different vehicle with a bigger engine. These aren't rare vehicles by any stretch.
 
#4 ·
Sounds like a stupid idea to me, a really stupid idea.

If you're going to go through the hassle (and expense) of an engine swap, you'd be better of putting a diesel engine (or something else) in there.

I wouldn't put a 3.7 turd in my TJ, not a chance in hell.
 
#6 ·
I'll try and respond to all posts. #1 if I'm swapping to a diesel it won't be a duramax turd. Have you heard of Cummins? The reason I was thinking 3.7 was because it as well as the 4.0 have been mated to the same transmission I have so minimal effort to get things to work together and I've wanted to stay with a jeep powerplant to make the wiring easier as well since some things are bound to talk to each other better. In the end it will probably be a 4.0 when the time comes because they are cheap and everywhere. I've thought about a regear because my jeep will rarely see mud or hardcore trails mostly gravel roads and my property so I don't want to tear too much stuff up. In order to regear to get around 2300 rpm at 70 mph I would have to drop to 3.55 and lose acceleration so more power is the answer. Why wouldn't a 210 hp 3.7l 6 speed manual with 3.73 gears perform better?
 
#7 ·
I'll be in the minority on this topic. I say do it. (well sorta)

You aren't going to really hurt the value of a 4cyl Jeep unless you set it on fire. (IMO, of course I think of 4 cyl jeeps as worthless. I know I'm a snob).

Power, it will be an increase.

Issue with current motors is not the physical action of swapping motors, or mounting things up. it's all the damn wiring for sensors and dodads.

If you have the skill, and the patience, you can do it. But don't expect it to go smoothly.

There's a decent group of guys that have done swaps (they usually go with v8's....and If I were you, that's the direction I'd go). There's companies who specialize in customizing wiring harnesses for engine swaps. They aren't cheap, but I'm told they do very good work and make things work "more better."

huge +1 to the cummins suggestion though. 4BT would be sweet.


overall point of these ramblings "If it tickles your pickle, have fun and take pics!!"
 
#8 ·
If you were going to spend the time, money and effort I'd think the 3.6 out of a newer wrangler would be much better than the 3.7. You have 265hp vs 210 and a power train that is in a few different jeeps right now.
 
#9 ·
Yeah I thought about the 3.6 but again trying to keep costs down and keep my stock transmission. I'm not looking for a hot rod so I feel the 200-210 hp would be fine. I know there are a lot of companies doing LS swaps that are supposed to be painless but then I need a new trans and I would need a stronger transfer case and then it'll probably snap the Dana 35 and 30 so 44's are in order so I might as well have bought a JK at that point.
 
#13 ·
I'm not looking for a hot rod so I feel the 200-210 hp would be fine.
If you are only really looking for a little more power, I'd honestly just use the 4.0. My old grand Cherokee had one and it definitely feels like a better motor in the Wrangler. Tune it and you'll have around 190hp from it will do everything you could reasonable do. Just my opinion, but hey if you want to swap a 3.7 roll with it. I'll sit back and watch with a cold one.
 
#10 ·
If your looking for a massive project, go for it with a swap. IMO 4cyl Jeeps have character some other Jeeps dont have.

They dont have alot of power, But they get alot of tough work done on the trail. If you are lacking power you may wanna regear even if you to have "Just 31's". Im guessing you have 31's by your name.

I have seen 4cyl Jeeps on 35's wheel with the big boys on tough trails. Your stock ratio is probably 4.10 or 3.73 and that is barely enough for 31's. You would see alot of improvement with 4.56, or going down in tire size.

If you are not running 31's my bad I just guessed by your screen name.
 
#11 ·
For info I did some research on doing the LS swap. Turns out I could probably still use the factory transmission and transfer case but the build list is not long but EXPENSIVE! Most prices are from quadratec so roughly.

Dana 44 front axle Detroit locker $2,777
Dana 44 rear axle Detroit locker $2,419
Rear driveshaft $424
Front driveshaft $475
Used 5.3 v8 low mileage $500
Radiator $450
Electric Fan $90
Swap kit with wiring and mounts etc $2,995
Grand total not including things that inevitably come up along a build $10,130

WOW!
 
#14 ·
Ha. Ok buddy. Good luck with your swapping engines. Seriously tho man, When people on here try and give you real world advise you should take it. I have personally owned 4 Wrangler/ CJs on top of other 4x4's and am a master certified auto tech.

Also, ask around about gear ratios and powerbands of 4 cylinder Jeeps. It will help you to research before Jumping to conclusions of engine swaps.

Your Jeep has the 2.4l they didnt use in the wrangler for very long. So Im not as sure of its durability. But let me tell you if you had the old 2.5l, it would take a "catastrophic event" or a real pile of miles to actually kill it.

No need for a pissing match either. I was trying to give you actual advise. I myself have swapped engines in Jeeps and other vehicles. And rebuilt engines and tansmissions.

And I was only mentioning that the correct axle ratio for your larger tires will bring your 2.4l back into its powerband. And with Lower gears you will easily be able to exceed 60 mph on the highway and not hurt the engine.
 
#15 ·
Yeah I'm not sure of the longevity of the 2.4 either that's the main reason for thinking of switching motors and more power of course. Honestly it's a low mileage jeep that doesn't have much signs of abuse or off-road use other than one plastic side molding missing. I'll be passing this jeep to one of my kids so I don't want to make it a trail rig.
 
#18 ·
I don't know if any CAN Bus engine is plug-and-play swappable with a different engine's CAN Bus. That would be the question to research. Plug-and-play, if possible, would be easier than replacing all the electronics.

The 3.7 was around during the era of pre- CAN Bus electronics, so it may be easier to interchange with some of the other old engines' electronics.
 
#19 ·
Is the motor mounts and will the standard tranny from a 3.7 bolt up to a 3.6. If not do they sell a kit to do so. Or should I get the standard tranny that comes with the 3.6, also will the tranny bolt in place of the original 3.7 tranny area. When I state standard, I mean a stuck shift tranny. Thank you for your help. I am trying to help a friend. His son blew up his 3.7. Now he want to go to 3.6 for the extra HP and torque.
 
#20 ·
The 3.6 does not fit in a Liberty. That sort of factored into the company's decision to discontinue Liberty when they did. They had the 3.2 on the drawing board as a potential replacement engine for the Liberty, but I imagine the company realized some economies by delaying the 3.2's development and limiting its deployment to newer platforms.

Just check a few sources of re-built engines, like Jasper. It's not a lot to spend if the vehicle is otherwise in good condition.
 
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