What power upgrades do you recomend?

I have an 07 liberty with a little over 1500 miles on it (had 31 miles when i bought it). I need more power. Ive looked around but I can't seem to find much for power upgrades other than chips and exhaust systems. Its looking like a big project will have to be done to get good power out of this engine, like forged pistons to accept a supercharger... won't be cheap either.

Shift kit, torque converter, and send your PCM off to B&G Chrysler.. That would be a good start.. O

let me know how it goes.

Mine is an automatic. Ill look into those suggestions though.

here is a good place to start:
http://www.lostkjs.com/forum/phpBB2/viewtopic.php?t=17536

I replaced the stock exhaust system with the dual output mopar exhaust. For what i paid for it at the time the mod was worth it. Since its gone up a couple hundred since then so you may want to look into magnaflow and gibson exhausts.

I put in an K&N FIPK; this mod was not worth it. Probably could get the same results with a K&N drop in filter.

I have the transgo shift kit for the 42rle sitting in its box at home. The kit itself is relatively inexpensive; but for most of us, it requires professional installation...which is why its still sitting in a box at home. If/when i find an inexpensive way to get the kit installed correctly i will complete this mod.

A second PCM is on its way so that i can send it to B&G for a reprogramming. I'm also waiting on a fastman ported throttle body.

No plans to add JBA headers. Between the initial cost, installation costs and the potential improvement, i don't think i will be happy with the results.

Links to all the things i've mentioned above are in the how to i linked at the start of this post. Good luck with your mods...if you do make changes, please post how they turn out.

cool thanks!

Bashgod said:

Mine is an automatic. Ill look into those suggestions though.

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Thats good, you can still upgrade all the parts that I said. O

JBA Headers???
Did those idiots finally start making the headers. Figures.
I waited for 8 months to get mine, then they told me they weren't going to do it, and cancelled the line. At least I got my money back.
BTW, with the headers, you'll have to reprogram your computer to match the new curves, they don't mention that.
(sorry still a little bitter about the whole thing)

Did those idiots finally start making the headers. Figures.

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Yea, but it seems like they only fit '05+. I'd be if i went thru what you and others went thru for nothing.

Just out of curiosity how much power do you need? And what purpose do you need more power for? Are you towing a trailer often with your Liberty?
I know my questions sound kind of stupid. I'm just curious because I find that the 3.7L has plenty of torque and horsepower. The acceleration is pretty good too. Gas mileage is pretty poor if you really step on the gas. But other than that, it seems to be more than adequate. Keep in mind, I'm all for more horsepower. I'd cram a 550HP V10 in my KJ if I thought I could make it fit. Do I need that kinda horsepower, nope! But it sure would be cool! Would be even cooler if I could afford to feed a beast like that! (biggrin)

I agree with rebelram.. I wouldnt mind to push my KJ alittle more if I could upgrade the upper end of the engine and put a shift kit in the ******.. I would flog the heck outta it. \/

Some cams along with better heads with better valves springs would be nice.. O

I hear ******'s never work the same after you do those install kits. I wasn't planning on that oe and probably won't do that.

what does reprogramming the PCM give you (power) and what does is cost? thanks

Bashgod said:

I hear ******'s never work the same after you do those install kits. I wasn't planning on that oe and probably won't do that.

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I explained that a little, in another thread, the TCM will eventually adjust, and it will go back to the way it was. You cannot bypass a computer with hardware in this manner. Once it sees values it doesn't like, with the shift kit, it will adjust pressures and solenoid timing all over again, to make up for what it sees as wrong. Shift Kits only work the way they SHOULD, in the 100% hydraulically controlled transmissions.

Powerslave said:

I explained that a little, in another thread, the TCM will eventually adjust, and it will go back to the way it was. You cannot bypass a computer with hardware in this manner. Once it sees values it doesn't like, with the shift kit, it will adjust pressures and solenoid timing all over again, to make up for what it sees as wrong. Shift Kits only work the way they SHOULD, in the 100% hydraulically controlled transmissions.

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Not 100% true.Mostly true for the 42RLE trans but when you add the shift kits to firm the shifts the shifts will always be firm until the clutches wearout,the TCM can not effect that only when it shifts in the 42RLE.If you are lucky to have the 45RFE trans the shift kit also firms the shifts which the TCM can not override(only when it shifts) and also includes a electronic mod(adding a resistor) to increase the line pressure which the TCM can not change since the resistor added makes the TCM "read" the info normal while the trans see's the increased line pressure.


The auto trans are still 95% mechanical and only 5% electronic still,no way around it.

Put in the 3.7's big brother, the 4.7!

rebelram said:

Just out of curiosity how much power do you need? And what purpose do you need more power for? Are you towing a trailer often with your Liberty?
I know my questions sound kind of stupid. I'm just curious because I find that the 3.7L has plenty of torque and horsepower. The acceleration is pretty good too. Gas mileage is pretty poor if you really step on the gas. But other than that, it seems to be more than adequate.

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X2... the 3.7 gasser has plenty of low-end torque for off-road and towing. I've never tested its drag racing or top end performance because that's not how I roll. But when I need the acceleration on the highway, it's there.

I don't like the shift points on the stock '04 but I live with them.

By the time you spend the money to gain at best 15-20 real world HP
you could regear
this will in effect make it seem to have more power but really make it use the power it has better
as long as you keep your tire OD under 30" and put in 4.10's ,the lowest you can go with 4wd, it will feel to have gained 50 hp
if you have a 2wd then just drop some 4.56's in the rear end
you will be cranking out 3500 rpm at 70 mph but will be able to keep up with most
"sports cars" from 0-60 ,if you can keep the tires on the ground

Bashgod said:

Its looking like a big project will have to be done to get good power out of this engine, like forged pistons to accept a supercharger... won't be cheap either.

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Supercharger? Sounds good to me. I watched "The Fast 'n Furious" just to see them stand the Charger on it's tail!
(bowdown)(bowdown)(bowdown)(bowdown)(bowdown)
But I too have to wonder about the need. Besides, that kind of power starts breaking other things like motor mounts, transmissions, drivelines, axles, the list goes on.

I asked a friend how he liked his sand rail. He said it was great, except that he worked on it more than drove it. Everytime he took it out, he broke something. He would replace that part with a stronger one only to find the new "weakest link" on the next outing.

Call me strange, but I like the "go cart" feel of my '06 Libby, and it doesn't seem underpowered at all.

Enough of my $.02.

If you want power, and want it "realatively" cheap, a good NO2 system will give you the most "bang" for the buck. The key is spending the bucks so it doesn't go "bang".

BTW, If you find a way to get 400HP, and plant it to the ground for a reasonable price - I'M ALL EARS! Far too many Civics with garbage cans for muflers running around these days. The look on their face when you toast 'em off a light in a Libby is PRICELESS! - done it many-a-time.

DISCLAIMER - Uncle Krusty does not condone street racing - unless I win.

Bashgod said:

I have an 07 liberty with a little over 1500 miles on it (had 31 miles when i bought it). I need more power. Ive looked around but I can't seem to find much for power upgrades other than chips and exhaust systems. Its looking like a big project will have to be done to get good power out of this engine, like forged pistons to accept a supercharger... won't be cheap either.

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I checked into the supercharger a couple of years back...
Well, if it is the one from this company...
http://www.kennebell.net/superchargers/dodge/liberty37/libert37.htm
Not to mention that they had some engine failures on them as well and replacements were difficult to come by from what I had read on other Jeep forums that had KJ sections!

Below is an excerpt I copied from Wiki books:
"Kenne Bell discontinued its supercharger for the Jeep Liberty's 3.7L engine. The relatively high piston rings in the 3.7L caused piston land weakness and failure, a problem correctable with forged pistons. A 4.7L supercharger can be installed onto the 3.7L, without issue, if a new tube and upgraded pistons are installed."
http://en.wikibooks.org/wiki/Jeep_Liberty/Performance

Why bother?
I would just as soon stuff a 4.7 liter V8 in my KJ before modifying a supercharger to fit the 3.7.


Too bad!

The problem with the 4.7, is you need EVERYTHING electronic with it...

Also, I know people who used the shift-kits in new Chrysler vehicles with UltraDrive and up, when they started the TCMs, and, it was ok for about 4-6 months, but the TCMs adjusted pressures based in the higher indexes, and they went BACK to the way they were; and in some cases, blew or cracked valves in the valve body because they WERE plastic. Not sure what they are now, die-cast or alum, but, if they are plastic, DON'T...

I know these are better Transmissions, but, the operation is the same. However, by all means, you go right ahead, anyone, and use the shift kit. Then get back to me in 4-6 months and let me know how it's "working" for you...