RegisterSearchFAQMemberlistUsergroupsLog in
Reply to topic Page 1 of 1
Aftermarket cats or no? Cant decide between headers?
Author Message
Reply with quote
Post Aftermarket cats or no? Cant decide between headers? 
I purchased a 00 old body style z71 tahoe.... the 5.7L about to hit 90k and I want to upgrade the exhaust. I have a JBA catback on the way already. I want to remove the stock brick manifolds. Hogg and several members on other board I have talked to are running the Hooker ceramic LT's with no EGR and praise them like no other. They run about $360ish shipped. They need headpipes fabbed, etc.

However, I found a deal on a set of Thorley ceramics for $525 shipped. Im afriad the hookers will cost more in the longrun due to the head pipes needing to be made, the bending, etc. I would need to get the truck tuned before or immediately after header install. That is what makes the Thorleys attractive, the fact that they come with the connector pipes, use egr, etc and I can wait on a tune later.

About the cats.. any idea how long the stockers are good for? I heard James B had problems with Carsound's... then again, I wont ever be force fed, maybe that was the issue.
Decision decisions... Im looking for some opinions.
Thanks in advance.

View user's profile Send private message Send e-mail AIM Address Yahoo Messenger MSN Messenger
Reply with quote
Post To make the Hooker Headers HOG has work for you 
The Hooker headers mentioned above have an O2 bung welded onto the header collector on the drivers side, but a hole needs to be drilled through the collector side wall to make it functional (easily done). Your L31 has two O2 sensors though, so a second bung will need to be sourced and welded to the passenger side header collector (a bit of welding, but still straight forward)

http://www.prostreetonline.com/buy/holley_weld-in_oxygen_sensor_bungs/

Also, the EGR fitting for GM trucks is a standard home plumbing male 5/8" flare fitting (NOT inverted flare fitting). You can find brass versions of this fitting at any home improvement store.
You can source your own steel fitting to weld/braze onto headers to connect up the EGR tube as needed to make non-smog compliant headers function as if they were compliant. Here is an example of the EGR fitting in steel where an enterprising individual could cut off the female end, and weld/braze the remaining tube with the male end to the exhaust manifold. This is EXACTLY what some other header manufacturers do to get a fitting for the GM EGR tube on their headers.

[img]http://store1.yimg.com/I/fittingsandadapters_1860_6329391[/img]

http://www.fittingsandadapters.com/90swivellond.html

Here is a picture below of a JBA Header for the L31 motor ('96-'00 GM 5.7) - Does the EGR fitting look familier???



Many have done this before you with good results. Not CARB certified for on-road use, but every bit as functional as if it were.

Good luck



Last edited by Pecos on Sun Jan 22, 2006 1:00 pm; edited 2 times in total
View user's profile Send private message
Reply with quote
Post  
Thanks.......... I know what has to be done, etc. Im just trying to weigh them out and see whats my best option.
I hate making decisions lol.

View user's profile Send private message Send e-mail AIM Address Yahoo Messenger MSN Messenger
Reply with quote
Post  
Those Hookers I have are now available in full stainless steel, the primaries are 1 5/8 x 2.5" collectors, 16 ga. stainless, part no. 2062 2HKR or ceramic coated, 2062 1HKR or just painted 2062 HKR, they are all availble from Summit for $723, $344 and $159.

peace
Hog

View user's profile Send private message
Reply with quote
Post  
woudlnt stainless steel get really damn hot? I thought ceramic was the way to go? Confused

View user's profile Send private message Send e-mail AIM Address Yahoo Messenger MSN Messenger
Reply with quote
Post  
The thermal transfer properties of Steel and Stainless steel are very similar. Ceramic coating on either Steel or Stainless steel is intended to be a thermal barrier so the heat does not disipate out the walls of the header as easily, and actually hold the heat inside the header to disipate further down the exhaust path. Headers have more surface area than stock exhaust manifolds, and therefire will disipate more heat into your engine compartment. Ceramic coating reduces this.

View user's profile Send private message
Reply with quote
Post  
Ive been watching all these threads about LT's i give up.

Im just gonna order some wack summit painted headers. 1 1/2 primaries.... $144.

Im not running lemans races--what difference does it make Wink


or maybe the edelcrock ti coated set..



same in regular ceramic



View user's profile Send private message
Reply with quote
Post  
i have the thorleys on my truck, they look good as the they i put them on. its been about 2 yrs now, thru MN winters aswell.. i love mine! just thought i would let u know...
Aj

View user's profile Send private message Send e-mail Visit poster's website AIM Address
Reply with quote
Post  
I have to wonder what Nylon Ties are used for on an exhaust manifold...

View user's profile Send private message
Reply with quote
Post  
you know, i didn't pay any attention. That is a good question..

someone should call edelbrock on lunch hour hahaha Rolling Eyes

View user's profile Send private message
Reply with quote
Post Dynomax cats 
are excellent. I paid something like 50 bucks each for mine, and the cost is still close to the same. Each one is capable of handling up to 455 cubes by themselves, so two of them on a 350 is no problem.

Either Comps or Thorleys would be fine, and there is no real issue with a head pipe. If running duals all you need is a collector reducer for the Comps as they are long tubes, which are pretty much needed anyway. The 200 dollar difference between the Thorleys and the Comps would more than cover the cost difference. Adding the extra bung for an O2 is no big deal for a competent shop, and the EGR should also be easily made. All it is is a tube that goes from the exhaust to the intake, not like it's anything complicated. The thing to consider is long tube makes more low end, tri-Ys will emphasize midrange. The Thorleys would be a lot easier to deal with though. I'm considering both of these headers for my own engine, have not made a decision on which but will most likely choose the Thorleys.

So. I'll suggest the Thorleys with Dynomax converters. This is the converter I've been using since something like 2001 or 2002, forgot when I had them installed but it was shortly after I bought the Tahoe. Had to lose that stupid rusted out single Flowmaster 50 series that was under it, could not talk when on the road with that POS under there. Oh and, the converter is now rated for a 460CID, when I bought my two they were rated for 455CID. My converters still look good, the only part of my Tahoe exhaust showing any damage is the tips have damaged chrome plating and the mufflers are just starting to show rust.



View user's profile Send private message Send e-mail
Reply with quote
Post  
James B. wrote:
I have to wonder what Nylon Ties are used for on an exhaust manifold...


Plug wires?????

View user's profile Send private message
Reply with quote
Post  
But theres only 3...

View user's profile Send private message
Reply with quote
Post  
Speeder you make a valid point. I think I will just go Thorleys again, but in a ceramic version. I ran the nickel's on my 98 and loved them. Afterall, Im not going to race this truck, etc... just wanna wake it up a bit.
Recommend anywhere in particular to get those Dynomax's?

View user's profile Send private message Send e-mail AIM Address Yahoo Messenger MSN Messenger
Reply with quote
Post  
summit or jegs

View user's profile Send private message
Reply with quote
Post I usually 
use Summit over Jeg's. No particular reason, other than prices tend to be a bit better there, and they have a larger selection than Jeg's. Plus, it's easier to find things on their site.

View user's profile Send private message Send e-mail
Display posts from previous:
Reply to topic Page 1 of 1
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum