Any real advantage to a true dual exhaust?

A student I know wants to use my Jeep for a class project to make a true dual exhaust system. The school will buy the headers and stainless tubing, I have to buy the mufflers and (gulp!) cat converters. They will fully weld the entire system, BUT, I will be without my Jeep for over a month and there is always a good chance that they will royally screw something up! What do you guys think? Is there any real benefit to going with a genuine dual exhaust? They will take one pipe off of three cylinders and another pipe off the other three. I'm not yet sure about routing because I have not yet brought it in for discussion. The other downside is, if they screw something up, I have to get it repaired or replaced myself.
Thoughts, comments, suggestions?
B.

Having been in a tech class in school, I would say that even if it would help, which I don't think it would at all, I wouldn't just let them take it and do it. Unless you can be there to watch what they're doing, I wouldn't give it to them for a second. Then again I like working on mine myself anyway!

They can't really screw anything up, by changing the exhaust, but what dual exhaust can do, is create a free flowing exhaust, which is good, for the higher RPM HP, but will hurt the low RPM torq, something that you want, the low RPM torque that is, if you are wheeling your truck. I wouldn't do it on an XJ.

Rob $.02

How do you do a real dual exhaust on a straight 6. just 2 exhaust manifolds or what?

It isn't even the exhuast work that would worry me. Students tend to make stupid mistakes, have accidents, or mess something up! Like I said though, thats just from my experience.

This thread is making my head hurt.
Who in the hell takes a month to make an exhaust system?
Are they going to bend the tube by hand?
The only thing a dual exhaust will do for a stock or lightly modded 4.0 is to take a little attention away from your mullet.
The loss of backpressure will rob low end power and torque, and routing the pipes would suck.
2 mufflers to bash up, 2 cats to fail, and I don't even want to think about O2 sensors and computer issues.
The money you spend on 2 cats and mufflers will buy you a nice Banks, Flowmaster, or Gibson cat-back system, and maybe a header and downtube.
Stick with a 2.5" single exhaust, and just make the truck breathe in and out a little easier.
HTH.

bgcntry72 said:

This thread is making my head hurt.
Who in the hell takes a month to make an exhaust system?
Are they going to bend the tube by hand?
The only thing a dual exhaust will do for a stock or lightly modded 4.0 is to take a little attention away from your mullet.
The loss of backpressure will rob low end power and torque, and routing the pipes would suck.
The money you spend on 2 cats and mufflers will buy you a nice Banks, Flowmaster, or Gibson cat-back system, and maybe a header and downtube.
Stick with a 2.5" single exhaust, and just make the truck breathe in and out a little easier.
HTH.

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What he said!

Thanks everyone, so far, I think I will pass on the "opportunity". It doesn't sound like it will have enough benefit to be worth it. Some answers:

felix: mostly a DD with some weekend warrioring, nothing rough, mostly just to get me to good fishing. Don't want to lose torque though, thanks for the heads up.

Ramsey: they would cut apart the headers and create two downtubes and go from there.

bgcntry72: they take a month because they will only work on it for about a half an hour per day and that includes planning, discussion and fixing mistakes. Thanks for the other info, I had not thought about sensors and stuff either.

Anyone else?

Thanks,
Brent.

bgcntry72 said:

This thread is making my head hurt.
Who in the hell takes a month to make an exhaust system?
Are they going to bend the tube by hand?
The only thing a dual exhaust will do for a stock or lightly modded 4.0 is to take a little attention away from your mullet.
The loss of backpressure will rob low end power and torque, and routing the pipes would suck.
2 mufflers to bash up, 2 cats to fail, and I don't even want to think about O2 sensors and computer issues.
The money you spend on 2 cats and mufflers will buy you a nice Banks, Flowmaster, or Gibson cat-back system, and maybe a header and downtube.
Stick with a 2.5" single exhaust, and just make the truck breathe in and out a little easier.
HTH.

Click to expand...

you can't argue with this. The comment is absolutely helpful.

a-b-s-o-r-b

Clifford makes a "dual exhaust" header for the I6 - but I don't think there's much of an advantage unless you are going to balance the thing to spin up around 7Krpm anyhow.

The principal advantage to a header is that the tube length can be tuned to take advantage of exhaust pulse timing, and that exhaust pulses can therefore be used to carry other pulses out simply because each pulse has a "low-pressure" area behind it in the pipe. That's why you'll notice that headers tend to look odd - all the pipes are meant to be the same length - synchronicity is the key.

Problem is, headers tend to be tuned for a fairly narrow exhaust range. They're a great idea for high-speed/high-performance engines and as a complement for forced induction, but you probably won't see a lot of advantage on a low-rev driver like your XJ.

I'd also have an issue with pipe routing and component location - the underbody area of the XJ just isn't very flexible in that regard. Throw in that a true dual exhaust tends to work best with a crossover pipe between the two halves, and where the Hell is THAT going to go?

That, and I wouldn't want my ENTIRE system welded - that little bolt-up flange just ahead of the catalytic converter is there for a reason - that reason being anytime you have to pull the transmission or get the collector out of the way.

Last, I'm another "DIY-er" - I don't even trust the smog guy to do HIS job right, and I watch him like a hawk. No way I'm going to let a nuch of greenies play with my truck for a month - besides, if you can't do an exhaust system inside of two days, you aren't doing mine...


5-90

360º headers all the way baby!
true dual exhaust CAN be tuned for torque, its just expensive and pointless, and really where is it going to fit. have them make you a stainless single exhaust.

Don't run dual exhaust. I did this once (don't ask), and had it exit at angles behind the rear wheels. Not only did it do nothing for performance, but everytime I backed up on the trail it hit the pipes and after about 6 months it looked like hell, not to mention there is no great way to run the pipes in the back. Mine rubbed the differential and rattled.......worst waste of money ever.

my question is more of where than why... i dont see any space to run 2 cats and 2 mufflers, the tcase is in the way, and then the insulation in the carpit is only on the passenger side... (but then i want things to look nice too...)

bgcntry72 said:

The only thing a dual exhaust will do for a stock or lightly modded 4.0 is to take a little attention away from your mullet.

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BC's still mad about losing his mullet

I saw a "dual" exhaust today on an XJ...looked hokie IMO.

Thanks everyone. Great input, I have officially shelved the idea. There is currently nothing wrong with my exhaust system so I think I will leave well enough alone. I appreciate the feedback.
Thanks again,
Brent.

my dad had fake dual exhaust on his 97. he liked the look so bought a flowmaster with 2 output pipes and had a local muff shop run "dual" exhaust. but there is no way he would get real dual... it would be pointless for an XJ
as everyone else said...stick with single
blackash

red91inWA said:

BC's still mad about losing his mullet

I am a sackrider, looking for instant street-cred.

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Fixed.

bgcntry72 said:

Fixed.

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THATS IT ?? I expected more from a slam master...'magine that... Disapointed again...

bgcntry72 said:

The only thing a dual exhaust will do for a stock or lightly modded 4.0 is to take a little attention away from your mullet.
HTH.

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LMFAO!

My Dad was the Principal of our High School here in NY.

We lost more parts - got parts 'switched' - and had jobs botched then I care to remember.

Buy a Factory Tech Manual for your vehicle & accumulate tools - much better.