I'd keep the stock manifold, I've only heard of manifolds rusting out when their wrapped in header wrap and that $130 could go somewhere else to improve reliability and durability. I question the quality of a stainless $130 header too.

 

Talk about some phoney exhaust talk.20 h.p from bigger pipe prove it andI 'll try to beleive you. Also guy a good quality S.Steel won't rust I see you don't know much about metal types so it's better not to say anything.

 

OK newbie, let me use your dyno and we'll see the actual numbers! I never claimed those numbers myself, those are numbers I've read from several sources and if you look at the CFM differences between 2 1/4 and 2 1/2 along with mandrel bends and an aftermarket muffler, the math sounds about right. My experiences also make them believable. Have you even done this upgrade?

Also guy, some high quality stainless can rust and corrode under certain conditions and I do know about different steel, aluminum and stainless grades, I'm not an expert, but I am an experienced welder by trade. Re-read my post, I was talking about wrapping the stock manifold and I doubt a $130 stainless manifold is going to be quality...like I said.

Keep your mouth shut, sit down and try reading posts first before responding newbie

 

did high flow cat & perfomance exhaust on 92 but kept pipe stock plus add after market air intake with open k/n filter noticed seat of the pants increase sorry no dyno. #s i would guess no more than 15hp but thats real hp keep in mind i drove it before & after dont bother changing the pipes you still need back pressure my 00xj bought in July has redesigned intake man. it plenty quick stock plus i like the quiet sounds better just my 2cts. PS the exhaust man. does crack how severe is yours?

 

It has 2 cracks in it now. Has a crack about 1 1/2 long running up and down and another lenght wise front to back. It sounds horrible and I can see fire spit out at night. Im gonna drill small holes at each end of the cracks before I weld it up. Gonna weld up the crack and make a pass down both sides of the main weld then cap it all together and grind it to maybe take some of the stress off the welds.Hope it wont crack out in the same spot.Thats how I weld up blocks and it seems to work.If there is a better way to do it please let me know. I want to replace my exhaust with mandrel bent pipe and get away from factory wrinkles. 1 1/4 or 1 1/2?

 

Brazing is a completely different process than welding. You don't need to drill holes on each end to stop the crack. A proper weld will completely fuse both sides of the crack. Also three passes is completely unnecessary, and would likely put to much heat into the manifold risking another crack, not to mention start warping the pipe. Just clean it as best you can and do one pass, going past the end of each crack. Grinding will just weaken the weld, just weld it, and leave it. Unground welds are always stronger. Annealing(de-stressing) can't be properly done at home and isn't necessary unless your manifold is mission critical for going to the moon. Heating with a torch is way to uneven and can create more problems than solutions. Go with 1 1/2 pipe past the cat, leave the 1 1/4 up stream from there like I said. Every aftermarket kit I've seen uses this 1 1/2" pipe, isn't too expensive and idiot proof.

If you don't have to pass emissions, weld up the EGR bung too. Eliminating the EGR will prevent idle and performance problems, help keep internal components clean, and allow your motor to use all 242 cubic inches. Just don't weld the O2 sensor bung and remove the O2 sensor before welding.

 

Yeah I can weld it up with mig, tig, stick, brazing it dont matter. Up until 1 1/2 year ago I worked in the oilfield welding/fabricator. Im gonna bend my own exhaust with my tubing bender that we build our dirt track cars with so it wont be expensive. We dont have to pass emission laws and this jeep came without a cat when I bought it. Just gonna replace all exhaust so its all new.

 

Than get a new 'muffler to cat' pipe at the parts house and run custom from there back, it has a flange that mounts on the tranny crossmember and manifold, has a dent in the right place for your front yoke and isn't expensive. FYI running any vehicle w/o a cat that came with one on public roads is illegal(theres a sticky at the top of the postings). The less you talk about your legal status, the better.

Its gonna be too dirty for a TIG, and too thin for SMAW. I've only seen and done brazing on cast iron, but I'd be worried doing it on a sheet metal manifold, plus brazing doesn't fuse the metal. I recommend a mig running .030" wire with a 75Ar/25CO2 mix. It'll give you a softer arc to prevent burn through and help keep the puddle clean. With the amount of time your gonna spend figuring out the bends and mistakes, a kit is worth it to me, but to each their own I say. Good luck

 

Nice stuff of header TheJerm. I like it.

 

Replacing the manifold with a equal length header especially a Stainless Steel one, is a no brainer. Its going to flow better and it will never rust and SS is stronger too.
There is great deals out there on headers.
No need for the full length but one that bolts place of the stock manifold.
Anytime you have to replace parts your always better off going with the best performance parts you can find.
Its about optimizing the performance that can be had from the engine. Not trying to build a racer but just make the engine as efficient as possible.
Everything that improves efficiency should help improve MPG too.

I did a long right up on headers, HP and Torque curves awhile back and not going into that whole dissertation again.
But remember that AMC/Chrysler built the Jeep as cheaply as possible and used the cheapest parts so with that in mind there nothing wrong with improving your jeep with better parts.

 

I put a full Borla exhaust system (header, cat-back) on my Wrangler a few years back and less than a year later it cracked. I have heard the same about Banks headers. It's not worth the money and the performance is barely noticeable. Go with a 2 piece cast iron manifold which came one 2000 and up Jeeps, you will need a Y-Pipe too but you can get all the stuff at a junk yard for less than $150 and you will never have the problem again.