H3 Exhaust System (Header, Catalytic Converter and Muffler)

[yevych]

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Hi guys, before this post I did spend couple of hours searching net - but didn't find all answers. I don't have experience with exhaust systems, so might ask stupid questions...
 
Apparently there are 3 parts starting from the engine and all the way to the back... Exhaust Manifold (with catalytic converter ??),  Catalytic converter and Muffler Mid Assy and Muffler Assy. 
 
I've got Magnaflow Muffler and Magnaflow Exhaust Manifold. Muffler looks good - but Manifold looks very poor quality. Are they all like that (see photo below)? 
http://www.canadianhummerclub.com/forum/index.php?/gallery/image/3655-maganflowheader/
 
It looks like H3 has 2 catalytic converters, one in Manifold and the other one as a separate piece between Manifold and Muffler. Why does it need 2? Is it legal to have 1 only?
 
Thanks in advance for help.
 

[whitehumh2]

Hi Mike,


I will post something a bit later, busy at the moment!


Kev

[whitehumh2]

HI Mike,
 
So I am assuming that you have the I-5 engine and not the V-8!
 
The catalytic in the manifold and the catalytic in the exhaust pipe are both necessary. They both address different emissions byproducts and are required to clean the exhaust. You are required to have both BY LAW! As well, most people think that a catalytic converter robs power and efficiency but that is a myth, they actually help to hold heat in the exhaust and balance the exhaust pulses all while promoting exhaust gas scavenging which fills the cylinder with a full fresh charge...so keep the CATS!!
 
Most exhaust headers look like the pic you linked. I would encourage you to take it and have it welded on the inside to increase strength and to promote better airflow!
 
Hope this helps!
 
Kev

[yevych]

[quote="Polar Bear"]
HI Mike,
 
So I am assuming that you have the I-5 engine and not the V-8!
 
The catalytic in the manifold and the catalytic in the exhaust pipe are both necessary. They both address different emissions byproducts and are required to clean the exhaust. You are required to have both BY LAW! As well, most people think that a catalytic converter robs power and efficiency but that is a myth, they actually help to hold heat in the exhaust and balance the exhaust pulses all while promoting exhaust gas scavenging which fills the cylinder with a full fresh charge...so keep the CATS!!
 
Most exhaust headers look like the pic you linked. I would encourage you to take it and have it welded on the inside to increase strength and to promote better airflow!
 
Hope this helps!
 
Kev
[/quote]
 
Kev, as always - really appreciate your help. Yes, I have i-5, 3.7L. What do you mean by 'it welded on the inside' ? Do you mean to flash/flatten those rough edges?  
Do you know if this Magnaflow manifold any better than original OEM?  It looks like it will require long hours to replace manifold due to the tight space. The other 2 pieces seems straight forward.
 
I'll definitely keep Exhaust system (muffler, etc...), but If I decide to keep manifold, I guess I better replace the whole line, including middle part (converter). 
 
Thanks again Kev. Always value your feedback. 

[whitehumh2]

[quote="humman"]
Kev, as always - really appreciate your help. Yes, I have i-5, 3.7L. What do you mean by 'it welded on the inside' ? Do you mean to flash/flatten those rough edges?  
Do you know if this Magnaflow manifold any better than original OEM?  It looks like it will require long hours to replace manifold due to the tight space. The other 2 pieces seems straight forward.
 
I'll definitely keep Exhaust system (muffler, etc...), but If I decide to keep manifold, I guess I better replace the whole line, including middle part (converter). 
 
Thanks again Kev. Always value your feedback. 
[/quote]
 
 
Hi Mike,
 
Yes I definitely mean to have the inside edges tapped back and into contact and welded to the header flange. But have a welding shop do it unless you have a MIG or TIG welder and know how to use it!
 
Replacing the headers on any vehicle will normally be about a 4 hour job but you will see that while it looks tight...everything magically just passes with the right manipulation of the part.
 
If you don't have them already, you need a header gasket and you should replace all your header bolts with ARP bolts or studs to ensure a solid clamping of the new header to the head.
 
Looking forward to seeing another one of your how to videos!! I enjoy them!
 
Later,
 
Kev

[yevych]

Exhaust is done... here is the sound of it.
 
https://www.youtube.com/watch?v=KhdNrJJE1Nw

[whitehumh2]

[quote="humman"]
Exhaust is done... here is the sound of it.
 
https://www.youtube.com/watch?v=KhdNrJJE1Nw
[/quote]
 
 
Well It sounds great!  BUT it would sound better if you were blasting thru a mudhole at the same time!!

[yevych]

hahaha, yea... I want to keep it shiny as long as I can - I think I'm falling in love with chrome again :-) ...

[Archngel]

they last,, had same one on all of my 3's even the Alpha and in the mud, they sounded great and you know what? mud doesn't stick to them,, hahahaha!