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Performance upgrades?

2784 Views 19 Replies 9 Participants Last post by  DaveJKJ
I've asked questions similar to this before, but I was just curious how you could possibly squeeze a little more out of the 3.7. I know it can't handle boost pressure from a super/turbocharger and I've done a CAI (and no one can agree if it works or not) and a magnaflow catback. Would JBA cat forward headers have any effect without damaging the picky catalytic converters/O2 sensors?
And aside from the headers, are there any other performance mods? I've heard a little about the fastman throttle bodies but I dont exactly know where I'm supposed to be looking and if it would help that much.

Separate from the performance mods, how would I go about regearing to 4.10's? such as where would I get the new gears and can any shop put them in? I know it's going to be a bit pricey...

Any information on these kind of upgrades would be great. Thanks, sorry I have so many questions for the forum..
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From the factory, you had a cold air intake system already. The pretty add-ons are cold air in your wallet intakes, do very little if any to increase power, just make the intake side of things louder=more power obviously:rolleyes: . The headers, doubtful they would really do a lot. You need to look at full length headers(which are not street legal on emission vehicles), or like on V8s, triple Y headers. Increasing throttlebody diameter can increase air flow and help top end power, but you end up with reduced intake velocities at lower rpms, robbing the engine of low end torque. That's the opposite of what you need! Now regearing, that will give you a performance increase, though costly for two axles. Driveline shops can do it, offroad shops(avoid tanner IMO), and a lot of independents can. The majority will want to use their parts partially to make their margin(hey they are in business to make money, not charity Obama work), and if you provide your own, expect a tail light warranty. Plenty of sources carry the gears, I'm sure jeepinbyal has them.
 

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Headers are no longer available from what I've heard they only fit a few years and were done away with due to low sales etc
 

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An exhaust and nitrous are about your only options haha
Exuast will do nothing but make more noise without internal engine mods and PCM tuning.NOS will only blow the engine up as it's basically like adding boost which the 3.7 can not handle with stock pistons.On another fourm a guy blew his 3.7 up with only a 50hp shot of NOS.
 

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Exuast will do nothing but make more noise without internal engine mods and PCM tuning.NOS will only blow the engine up as it's basically like adding boost which the 3.7 can not handle with stock pistons.On another fourm a guy blew his 3.7 up with only a 50hp shot of NOS.
Expensive 50hp shot..................who did that, someone on LOST?
 

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Coming from autocross racing, this is the age old how to get more power question. Bottomline is that if there was a cheap easy way to do it, Jeep would have done it. You want naturally aspirated power and have some cash to blow, engine swap it is. You could adjust your speedo for five miles over. At least that way you'd think you're going faster lol.
 

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That, or do a full tear down and put in some forged pistons, upgrade the valve seats, etc, and force induction. Someone was working on a 4.7L swap, and there is a member with a 302 in his. These aren't race machines, and never were meant to be. If you think we lack power, go drive an old FJ60.
 

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That, or do a full tear down and put in some forged pistons, upgrade the valve seats, etc, and force induction. Someone was working on a 4.7L swap, and there is a member with a 302 in his. These aren't race machines, and never were meant to be. If you think we lack power, go drive an old FJ60.
The 4.7 swap on Facebook was done and then sold right away ??? Wonder why?
Someone else posted they had done one but never said how or if any issues then disappeared. Seems each one thats been done disappears right after its done so no one really knows how well they work or don't
The 302 is still sitting and not finished, motor is just sitting down in the KJ
 

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Has anyone ever thought of the srt4 engine in the liberty? I read somewhere that you can do this swap in a jk/tj. I dont know if this would actually work but hp was like 240 and with tuning easly get 300+. Of course turbo lag would play a huge role in offroad ability.
 

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Since you own a 2005, you can get a hypertech tuner. Advertises roughly 25 hp/tq. The few people who got one report good results with it. The WK guys especially love it. :thumbsup:
So, the hypertech tuner only works in an 05? Haven't seen that option/mod done on a KJ. Just curious.
 

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Has anyone ever thought of the srt4 engine in the liberty? I read somewhere that you can do this swap in a jk/tj. I dont know if this would actually work but hp was like 240 and with tuning easly get 300+. Of course turbo lag would play a huge role in offroad ability.
You would almost never even use the turbo. The only fi that would make sense is a supercharger. I don't know much about that srt 4 motor except it is similar to an evo engine. The internals should be able to handle the sc though. Either way this sounds like so much work, no amount of power gains would even outweigh the hassle of making it work.
 

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Discussion Starter · #16 ·
How much would I be looking at for parts and labor to regear? That's been on my mind for a while.

And not that I really have the funds to do it, but how much would it cost to basically reman the engine to the point where I could run some boost?

And does anyone have more info on the hypertech tuner or does anyone currently run that?

Finally, on the headers, I know these are expensive, but has anyone used these ones? would they ruin my O2 sensors?
http://www.autoanything.com/exhausts-mufflers/61A2280A0A0.aspx
 

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How much would I be looking at for parts and labor to regear? That's been on my mind for a while.

And not that I really have the funds to do it, but how much would it cost to basically reman the engine to the point where I could run some boost?

And does anyone have more info on the hypertech tuner or does anyone currently run that?

Finally, on the headers, I know these are expensive, but has anyone used these ones? would they ruin my O2 sensors?
http://www.autoanything.com/exhausts-mufflers/61A2280A0A0.aspx
It would run around $1200-$1800 to regear to 4.10's,more if you add lockers at the same time.Rebuilding the engine to handle boost would be around $2500-$3500 then what ever a custom turbo kit/supercharger kit would run which would be well over $5000.And finally no one makes long tube headers for the 3.7,let alone a KJ.JBA once made shortie headers but stopped production over a year ago so finding them maybe hard and you will gain nothing in the lowend.
 

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Shorty headers aren't real efficient. Add to that the additional heat under the hood, its probably a wash. Try a regear first, and see how it responds, you may be happy with how it wakes up. From there, figure an engine swap if you really want more power.
 

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Shorty headers aren't real efficient. Add to that the additional heat under the hood, its probably a wash. Try a regear first, and see how it responds, you may be happy with how it wakes up. From there, figure an engine swap if you really want more power.
Agree with the regear. Probably would be cheaper to regear and there should be more cost/results benefit.
 
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