Any opinions on Headers / Exhaust?

[mingez]

Pros/cons - or any reasons for buying one brand over another.

Thanks ahead of time.

[MudderChuck]

Just an oppinion, but it has been said, the stock header on the I-6 injected is a pretty good header. Though they have been known to crack. The next time, I replace the Cat. and Cat. back pieces, I´ll probably go to a 2 1/2 inch Cat. and exhaust. Not particularly a why thing, but more of a, why not thing. Doesn´t really cost much more. Not gonna get into any high tech. systems, good enough, is good enough.
Besides, I have a nasty habit of dinging new exhaust systems. Always seem to flatten or bend the new ones. The old rotten ones, just seem to hang there, with me hoping, they would fall off, so I could put a new one in.
I usually choose my exhaust systems, by wall thickness, rust inhibitive coating, high flow muffler, not to noisey. Next Cat is gonna be a little larger than stock, the stock replacement Cat. is pretty darn small and doesn´t (can´t) flow very well, with age and soot. And hope it doesn´t mess up my next smog test.

[mingez]

So your opinion is not to change headers? You'd think that with all of the after market headers out there for the XJ that their must be a performance difference.

Bigger Cat and up grade Muffler. Okay. Now what about Dual Exhaust? I haven't heard much on this in the forum.

Thanks.

[MudderChuck]

Just an oppinion, (if it ain´t broke don´t fix it) and mostly gleaned from somebody else´s research. The I-6 motor, is mostly a mid range motor, nothing much to be gained, by helping it to rev. faster, into the higher RPM range. Even with an open exhaust, a motor runs stronger in different RPM bands, depending, on design, diameter, length of the collector. Matched sets, intake, flow, exhaust, tuned to work together, seems like the best approach.
Don´t really think, I´m gonna take the chance, of breaking off the exhaust/intake studs, unhook all that junk, try not to break any injector connectors and some other soft points. For a 7 or even 15% horsepower increase, that might make, my motor run lean (the motor killer) at certain RPM´s.
If the exhaust manifold (header) was cracked, I might be temped. Other than that, I´d probably stick with the flange at the front of the Cat and work the system towards the end. If I felt the need.
If I installed, a header and my plugs started to burn bone white, I´d think seriously, about removing it and/or figureing out a way to get some more fuel.
Some headers, are pulse scavenger types, the pulse helps remove, excess exhaust from the cylinder, allowing a little more room, for new air/ fuel mix ( more oxygen), while residual exhaust (in a slightly restricted system), slows down the burn some, allowing for slower combustion (more uniform heat/less chance of explosion). A lot of interelated events going on in there.
I started out, on carburated motors, a typical 14:1 air fuel mixture, makes me crindge. Used to be a sure formula for a blown motor. Works now on days, with computer controlled vehicles.
I´ve still got, a set of flange spacers, three hole flange inserts with different sized openings. 2", 2 1/4", 2 1/2", 3" etc., to be inserted between the collector and the exhaust cone. Also a set of collector extensions. Amazing what tuning, an exhaust, will do to the torque, at certain RPM bands and loads. Without even changing the header. Sometimes back pressure is a good thing.

[XJNick]

I thought dual exhaust only benefited V style engines?

I agree with MudderChuck though, If it ain't broke don't fix it

-Nick

[mingez]

Uhhhhhh

Thanks. Dude, you speak languages that I'm too newbie to understand. But, you were extremely helpful. After I translated your post with my English to Mechanic dictionary, your basic message is: don't mess with what works. And it is working. Everything is stock and I have yet to lose a hill climb to ANY V8. Sure makes me happy!

But much like all jeep owners/ 4x4 enthusiasts I want more power. I'll take your advice and go the route of gearing up. Thank you all soo much! I love this damn site.

[sparkyshotrods25]

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[jammerjamesharmon]

Borla for the big HP increase with bored throttle body from Jeeperz Creeperz. Check out my rig @ www.geocities.com/jammerjamesharmon