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  #1  
Old March 25th, 2019, 18:46
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ShoeterMcgav ShoeterMcgav is offline
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The end all Exhaust/ Header thread!

Yes.. Another thread about headers, manifolds, down pipes, and exhuast... Maybe a single thread can harbor all the most recent pros and cons- dos and donts and make it a little easier for new comers to the XJ world *in a wonderful sticky! Until then- here is my findings and questions:

First off... ALL factory exhuast manifolds/ china headers leak or will leak, and most aftermarkets. Its a special note that when replacing the mani/ header CHANGE THE MOTOR MOUNTS! Prime time to do it as the driver side is exposed- and worn out mounts will crack your new header. On this note all hangers should be TIGHT! As in little to no up/ down movement. Again to keep the pressure off the new header to prevent it from cracking too. One way to help this is a piece of flex pipe installed near the bottom of the downpipe or there abouts. Where the exhuast makes the turn that straight section seems like a good bet- anywhere before the cat is what is recommended.

Now, here is the question... The stock mani is very similar to a header, not a bulky cast mani with poor flow. Its probably debatable how much is gained going to a true header that extends each outlet to the Y section. Experience here? Actual gains? 4wheel parts (usually $$$) has a nice manifold replacement for a decent price with 2 flex joints to prevent cracking- I kinda dig it!

Thoughts on this piece?

https://www.4wheelparts.com/p/omix-a...fold-kits/7996

Is there any super gainz going with say a cheaper chinatown fleaBay special for under $100? I know these are all the same design- some even claim the one Banks uses- but usually need the connecting rod cut and/or trimming/ grinding to make fit.. Like one of these?

https://m.ebay.com/itm/RACING-MANIFO...l_noapp=t rue


Summit carries one that seems a littttle better:

https://www.summitracing.com/parts/atp-101212/

Coming from the ZJ world I have a high regard for Doug Thorley headers from Kolak- since no one else made em and they were saweeet! However im not looking to fork over that kind of coin on this...

SO is Protuning lab an acceptable median? I like that the Y pipe comes with it, since I will need a whole new exhuast system here- Anyone run this?

https://www.protuninglab.com/hds-jc9140-yp.html

There are others.. Like these, but $$$$ Gibson likely the best... Borla and Rugged Ridge close behind.




Next is cat, muffler, and piping. While a flowmaster or magnaflow cat isnt really going to do much- any input here? Flow master universal from VatoZone is like 60 bucks.. Im with it. Then maybe a flow master 40 series? Do cat backs make much difference on these rigs??

If a decent muffler and cat can be had for less then 200$ I think thats how Id probably roll... And have a local shop run the rest of the pipe for less then 100 so like 300 cap plus header/ mani.

Theeeen... There is this option, full bolt on but brands unknown for cat and muffler:

https://www.upsw.com/1997-jeep-chero...YaAmfqEALw_wcB




I've been putting off posting this thread... Knowing itd be a heck of a long first thread here! (And a pita from my cell [excuse grammer errors]) BUT I need to pull the trigger soon, the new rig needs to pass emmisions soon.

Sooooooo-

Thanks for any and all input!
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  #2  
Old March 26th, 2019, 18:50
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ShoeterMcgav ShoeterMcgav is offline
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Re: The end all Exhaust/ Header thread!

Seemed like a good idea at the time... Maybe to lengthy to get replies?

Probably just get the ebay cheapo
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  #3  
Old March 26th, 2019, 18:52
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Re: The end all Exhaust/ Header thread!

Shoulda started off with the how much lift to fit 3x" size tires LOL
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  #4  
Old March 26th, 2019, 21:40
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Re: The end all Exhaust/ Header thread!

i waiting myself to see a response as i have just swapped a 2000+ grand cherokee 4.0 in my renix jeep to get it running imreused the renix stuff but want to upgrade i buy a header i round at junkyard similar to,one you posted with the bellows but am looking how im going to run the rest
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  #5  
Old March 27th, 2019, 04:25
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Re: The end all Exhaust/ Header thread!

The exhaust manifolds with bellows are just stock replacements, no major gains in flow or HP. The "racing" manifold is more like an actual header than the stock manifolds. Instead of two long pipes and 4 short pipes as on the stock manifold, it has 6 pipes that are more equal in length. It is very similar to the APN manifold that many 4.0L owners have installed. Expect to gain a few HP and a bit of bottom end response.

No single improvement to exhaust or intake is a magical power booster, but you can make small gains at each choke point. The engine is an air pump, more air out via the manifold, cat, exhaust system, allows more air in thru the intake and head.
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  #6  
Old March 27th, 2019, 04:46
Scrubber3 Scrubber3 is offline
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The end all Exhaust/ Header thread!

For us with the cats attached to the manifold, is there a solution to replacing these with non catted manifolds without triggering the check engine light?
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  #7  
Old March 27th, 2019, 11:25
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Re: The end all Exhaust/ Header thread!

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Originally Posted by Scrubber3 View Post
For us with the cats attached to the manifold, is there a solution to replacing these with non catted manifolds without triggering the check engine light?

O2 sensor simulators and weld 2 bungs for the upstream sensors on the new manifold/header.
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  #8  
Old March 27th, 2019, 12:59
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ShoeterMcgav ShoeterMcgav is offline
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Re: The end all Exhaust/ Header thread!

While the gains in flow would be minimal with just a header vs the stock piece- its not my primary concern. Only way exhuast will be the limitimg factor is if more air is coming in. With out porting or head or stroking or forced air... Im sure its a slight if any increase to power with a true header.

Running one with 3 inch exhuast all the way back for instance wont just magically give the engine more power. Imonthe stock exhuast is better flowing then most cars. Id agree a cai with header would be an upgrade to stock- but nothing over 15--20hp max

Mine is cracked. So it needs replacement. Bang for buck is primary concern for me.

Ebay header or protuning lab is where im leaning
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  #9  
Old March 27th, 2019, 13:18
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Re: The end all Exhaust/ Header thread!

https://www.google.com/amp/s/www.jee...11905/%3famp=1

The more i read the less i want to pull the trigger on shiny "headers"... Cheap ones seem cheap and more prone to crack. The manifold with the 2 flex pieces in the long tubes might be best for not cracking down the line. Maybe hitemp paint em to keep heat in better. Still debating which route to go
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  #10  
Old March 27th, 2019, 14:07
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Re: The end all Exhaust/ Header thread!

Quote:
Originally Posted by ShoeterMcgav View Post
While the gains in flow would be minimal with just a header vs the stock piece- its not my primary concern. Only way exhuast will be the limitimg factor is if more air is coming in. With out porting or head or stroking or forced air... Im sure its a slight if any increase to power with a true header.
My 1997 XJ had a full Banks exhaust system, installed by the PO.
It didn't make much of indifference in power or mileage until the head and intake manifold was professionally ported and flow matched. This really woke up the engine.

Same with my 2001, a Banks header did nothing until the head was ported.
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  #11  
Old March 27th, 2019, 16:16
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Re: The end all Exhaust/ Header thread!

My 1998 had the very common cracked stock exhaust manifold and a rusted out muffler. The exhaust manifold crack was small and nearly closed itself when the engine warmed up. It ran well, got good gas mpg's, and had no CEL. I replaced the stock manifold with an APN, installed a fresh cat, and an IRO catback exhaust. I did notice a difference in the exhaust sound, a slight difference in the bottom end torque, and maybe gained between 5-10 HP.

All in all not massive difference but enough to notice. I agree that porting the head is a good idea, and necessary to maximize the potential gains.
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Go ahead and slam the liftgate down on a blanket, and see how long you are laughing.
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  #12  
Old March 27th, 2019, 21:08
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Re: The end all Exhaust/ Header thread!

Huh... I read a bunch of hate and horror about APN... Fpund one for 150 plus shipping. Might go that route. Looks less cheap then the flebay and protuning models
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Old March 28th, 2019, 01:24
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4x4JeePmaNthINg 4x4JeePmaNthINg is offline
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Re: The end all Exhaust/ Header thread!

Quote:
Originally Posted by Tim_MN View Post
The exhaust manifolds with bellows are just stock replacements, no major gains in flow or HP. The "racing" manifold is more like an actual header than the stock manifolds. Instead of two long pipes and 4 short pipes as on the stock manifold, it has 6 pipes that are more equal in length. It is very similar to the APN manifold that many 4.0L owners have installed. Expect to gain a few HP and a bit of bottom end response.

No single improvement to exhaust or intake is a magical power booster, but you can make small gains at each choke point. The engine is an air pump, more air out via the manifold, cat, exhaust system, allows more air in thru the intake and head.

Is there a point were you can get too much flow, I've heard the 4.0 likes some back pressure?
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Old March 28th, 2019, 06:53
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Re: The end all Exhaust/ Header thread!

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Originally Posted by 4x4JeePmaNthINg View Post
Is there a point were you can get too much flow, I've heard the 4.0 likes some back pressure?
Well, back pressure is a bit of a misnomer, IMHO. Years ago, I replaced the aging cat back with a high flow cat and Rusty's FM50 fitted with 2.5" pipe all the way out and lost plenty of low end power. Not to mention the droning was insane especially between 2,000 and 2,500 RPM.

After several weeks of hair pulling, I call FM (Flow Master). I was told that because of the low RPM, small cubic inch and length of the exhaust it was important to size the pipe properly to get sufficient flow.

My solution,... replaced the last 18" of pipe with the OEM piece which is 2.125". I regained the lost low end power and got rid of the exhaust drone. What the FM rep told me made a lot of sense to me. The length and size of the 2.5" pipe allowed the gases to cool down significantly. This in turn allow the gases to get heavy which resulted in a reduced velocity at which it exit.

It could be referred to as back pressure although I look at back pressure as something that is caused by clogged piping.
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1996 XJ; 4.0L; AW4; NP231; SYE; D30 and D44; ECTED; 4.10 gears; 30X9.5 -15 BFG/AT/KO; 3" lift; Rusty's LCA; JKS ADJ UCA; Kevins ADJ Track bar; Drawtite Front Receiver; Dual Electric Fans; Dual Battaries.
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Old March 29th, 2019, 16:10
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Re: The end all Exhaust/ Header thread!

Is there any venders here or reccomended places to purchase the APN? Looks like better material then the prodrive and ebay options.. Cheapest i found was a buck
sixty plus shipping. Also is labeled as a manifold and not a true header-

http://www.jeep-exhaust-manifold.com
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