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Just wondering if anyone knew of headers available for the 3.7L models. K&N Intake, Exhaust, and Jet Chip still dont give me the torque I want with my 32" toyos and lift.
 

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JBA makes headers that fit the 3.7L in our Commanders...they start about $500.00. If you get a set, let us know how they do. Just a lil too rich for my blood.
 

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yes let me know what they are doing for you as well.
 

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I have heard of many people with the 3.7 in the new 4 door JK wrangler. They love the engine for its fuel economy, its quiet, and very dependable. They don't like that no matter what they do to it it won't make the torque they want. The only way they can get the performance offroad they need is to swap gearsets. The lower gear set isn't great for the highway but it does help get that engine to perform. Do you know your gear ratio in the axles?
 

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v6 has 3.07 gears in the axle. what was jeep thinking????

but i digress.

just switch out from 3.07 gears to 3.73 gears. it will be cheaper and more effective then headers on a v6
 

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adamag25 said:
I have heard of many people with the 3.7 in the new 4 door JK wrangler. They love the engine for its fuel economy, its quiet, and very dependable. They don't like that no matter what they do to it it won't make the torque they want. The only way they can get the performance offroad they need is to swap gearsets. The lower gear set isn't great for the highway but it does help get that engine to perform. Do you know your gear ratio in the axles?

The wranglers come with a 3.8 Liter V6 not a 3.7 Liter.
 

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my mistake, despite that I doubt that the .1L will make a huge difference. When it comes to a lift and tires, axle ratio has more to do with torque than engine performance. I agree with 4.7 the gearset swap will be more effective and less costly to get you to have more power to the wheels. For example look at a old wrangler with a 4cyl and 35's on it. The gearset is probably at least a 4.10 or higher.
 

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adamag25 said:
my mistake, despite that I doubt that the .1L will make a huge difference. When it comes to a lift and tires, axle ratio has more to do with torque than engine performance. I agree with 4.7 the gearset swap will be more effective and less costly to get you to have more power to the wheels. For example look at a old wrangler with a 4cyl and 35's on it. The gearset is probably at least a 4.10 or higher.
Not that im purposely trying to correct you but 4.10 gears on a 4 cyl and 35's would be a complete dog. You would need some 4.88's in the axles. Its also a lower gear ratio, just a numerically higher number.
 

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The topic of this thread is headers!!!
 

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4.7commander said:
v6 has 3.07 gears in the axle. what was jeep thinking????

but i digress.

just switch out from 3.07 gears to 3.73 gears. it will be cheaper and more effective then headers on a v6
Where do you go to get gears installed that would be cheaper to buy both front and rear 3.73 gears and get them installed for under $500-600 dollars. (The cost of headers).

I also would take gears over headers anyday. Especially if you only have 3.07's. I feel sorry for those guys with lifted commanders and the V6, they got screwed!
 

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well then someone tell me where to get the 3.73 gears and i will go have it done.lol
 

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I have every tool needed to do gears and about 18 available lifts to do it, but dont have the knowledge on how to do it. Bring someone that does and we can get you hooked up.
 

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well where can i purchase them at? i cant seem to find them and wouldnt know what ones to get for my veh and everything. i am lost on which ones to purchase can anyone help me out and paste a link to the 3.73 gears that would fit in my veh.
 

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07JeepXK said:
Not that im purposely trying to correct you but 4.10 gears on a 4 cyl and 35's would be a complete dog. You would need some 4.88's in the axles. Its also a lower gear ratio, just a numerically higher number.
Just trying to make a point. I would only use a 4 cyl for a beater anyway. the 258ci was where it was at!
 

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go find a couple diff's in the junk yard from an XK or WK and install them. just make sure you get 3.73 gears. they may sell them cheap if you offer to trade your old axles in on them.
 

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ya i will look into doing that.
 

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Discussion Starter #17
the main issue i have with doing a gear swap is the labor it's going to cost me. Assuming I had the knowledge of how to do it myself (which I dont) i would also need a fairly sturdy truck lift and/or multiple jacks and stands. (which I do not). realistically headers won't add much in the way of torque by themselves without a substantial computer overall (my stage 2 jetchip may be able to pull some more out of headers). I can also look at pulling the cat out or modifying the baffling. I would also feel more comfortable buying aftermarket gear sets than junkyard hopping because of the warranty that may (or may not) come with them. i would rather have junkyards parts, especially those that come out of abused jeeps, stay out of my truck. If I do get the headers slapped on (seriously considering) I'll be sure to post updates.
 

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runit3 said:
the main issue i have with doing a gear swap is the labor it's going to cost me. Assuming I had the knowledge of how to do it myself (which I dont) i would also need a fairly sturdy truck lift and/or multiple jacks and stands. (which I do not). realistically headers won't add much in the way of torque by themselves without a substantial computer overall (my stage 2 jetchip may be able to pull some more out of headers). I can also look at pulling the cat out or modifying the baffling. I would also feel more comfortable buying aftermarket gear sets than junkyard hopping because of the warranty that may (or may not) come with them. i would rather have junkyards parts, especially those that come out of abused jeeps, stay out of my truck. If I do get the headers slapped on (seriously considering) I'll be sure to post updates.
That's why 4.7 suggested finding a front and rear axle set from a wrecked WK or XK, then it would be a direct swap and configuration in the computer with the StarScan (yes, you have to have the ECU changed too). No one makes aftermarket gearsets for the the front diff in the WK/XK, which is why nobody on the site can go any higher than 3.73 ratio. The junkyard axles should be new enough that they would be covered under the drivetrain warranty since they're still an OEM item. You can do the swap yourself, saving on the labor costs.

Headers won't do anything noticeable with the 3.7 in the XK except make the engine noise louder. Pulling the cat will void your warranty and make you fail emissions. You live in enviro-land, so I wouldn't go that route.
 

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I'm in the process of looking for an axle to swap but make sure if you do this that the one you pick out has the same diff set up...not sure if the electronic limited slip would work with the 3.7L pcm. If you want power, install a supercharger or turbo and find someone to reprogram your pcm...easy 100hp....draw backs...no one makes this kit and it would cost about $5K if available.
 
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