View Full Version : Best Flowing Cast Iron LS1/2/6 Exhaust Manifolds?


jweb47
12-08-2009, 06:53 PM
Sorry if this is a repeat but, I can't find a link I had that showed what is considered as the best flowing stock cast iron exhaust manifolds. I believe they came on Vette LS2s. Does anyone here have any input on this? Thanks

rojs234
12-09-2009, 01:08 PM
Sorry if this is a repeat but, I can't find a link I had that showed what is considered as the best flowing stock cast iron exhaust manifolds. I believe they came on Vette LS2s. Does anyone here have any input on this? Thanks
Funny, I saw this thread and I had just been reading some older Hot Rod Magazine dyno tests last night that had an article on the " new then " LS2. One of the tests was a comparison of the LS2's exhaust manifolds to the earlier LS6 or Z06 exhausts. Katech did the tests and the LS6's were better everywhere on the scale by 4 to 5 numbers except at 2000 Rpm. A few years ago Car Craft tested the GTO type manifolds against headers and they did very well. I guess it probably depends on what you are trying to fit them into.
I have a set of the Corvette Ls6's on a 6.0 in a ' 34 Ford streetrod and they work really well. I also have a set of the GTO's that wouldn't QUITE fit in the car that I would sell if they will fit your application. $70.00 shipped in the lower 48. April ' 05 Hot ROD for the Katech article and January ' 05 Car Craft for tests of GTO against LS1 manifolds and headers.

jweb47
12-09-2009, 02:57 PM
Wow...I'm really glad you saw my post and took the time to respond. That may be the article I'm thinking about. About the GTO manifolds...I have a set from a 04 and they look pretty efficient except the output flange is only 2". What year GTO are yours and what size flange? I'm doing a transplant in my 69 Camaro. Thanks

rojs234
12-10-2009, 10:41 AM
Wow...I'm really glad you saw my post and took the time to respond. That may be the article I'm thinking about. About the GTO manifolds...I have a set from a 04 and they look pretty efficient except the output flange is only 2". What year GTO are yours and what size flange? I'm doing a transplant in my 69 Camaro. Thanks
Not sure of the year on mine, but I thought they were all made the same. I'm pretty sure they take 2 1/2" pipes. It probably doesn't matter though, because I don't think they will fit a ' 69 Camaro. Maybe someone else on here will know for sure. Sorry! Ron

jweb47
12-10-2009, 10:52 AM
I haven't been able to find those articles yet...

NOS327
12-14-2009, 10:21 PM
I'll have these '06 LS2 GTO manifolds for sale shortly...

I'm skeptical that they'd fit in a camaro chassis though, probably run into the upper a-frame and/or cross shaft.

http://i117.photobucket.com/albums/o67/TJ_Johnson/LS2%20Build/LS2EngineHarness.jpg

http://i117.photobucket.com/albums/o67/TJ_Johnson/LS2%20Build/AllLS2.jpg

both pics of passenger side, but are very symmetric.

jweb47
12-15-2009, 08:59 AM
What is the diameter of the output flange? 04s are 2".

Patrick G
12-16-2009, 05:48 PM
Best flowing manifolds are the ones that come on the C6 Z06 (with 427 ci LS7 engine). They only fit a Corvette, but they rival headers for flow.

Paul57
01-19-2010, 06:58 AM
Is this the carcraft article...???
http://www.carcraft.com/techarticles/ls1_engine_header_test/index.html

The pic is of the GTO manifold but they are saying it is a Vette manifold.
Is it possible that a 2" collector could come close to matching a header??????
I wonder if they messed up the pic??

jweb47
01-19-2010, 10:13 AM
I think that's it...you make sense because the 04 GTO LS2 manifols have 2" collectors.

Paul57
01-19-2010, 12:12 PM
I missed some interesting details in the article. It does sound like the pic and info about the GTO manifolds ("Corvette-configured") may be correct. It is just hard to believe that a 2" collector could do that well. What do you guys think??

"The GM Performance Parts LS1, that our friends at Scoggin-Dickey Performance Center in Lubbock, Texas, are helping us test, comes in an interesting configuration. According to our pals at GM Performance Parts, this engine is actually a GTO engine, but it comes with an F-car (Camaro/Firebird) oil pan and Corvette-configured exhaust manifolds. The exhaust manifolds became a very important consideration once we started our dyno-testing."

jweb47
01-19-2010, 01:37 PM
Ditto for me as well...are the 2" GTO manifolds that good or did they make a mistake? Thanks

SweetS10V8
01-19-2010, 01:49 PM
ANyone thought of having your current manifolds extrude honed?

http://www.gethoned.com/

jweb47
01-19-2010, 01:57 PM
At that price, I could buy great headers ready to bolt on...

SweetS10V8
01-21-2010, 08:10 AM
The only reason to swap from one stock manifold to another is becasue you live in California or somewhere where you cant get away with headers. If thats not the case, why are we talking about this???

Just buy headers.....

jweb47
01-21-2010, 09:29 AM
Because I want to know...that's why. If Gen. III & IV headers were priced comparable to other engine headers, that would be the way to go. But they're not and I'm NOT paying 800.00 or more for tube headers. Besides that, the manifolds I'm trying to locate flow almost as well as tubes and fit better.

rojs234
01-21-2010, 11:26 AM
Is this the carcraft article...???
http://www.carcraft.com/techarticles/ls1_engine_header_test/index.html

The pic is of the GTO manifold but they are saying it is a Vette manifold.
Is it possible that a 2" collector could come close to matching a header??????
I wonder if they messed up the pic??

That is a reprint of the original Car Craft article, and even though they called them 'vette manifolds, they are in fact GTO. In the original article the picture was big enough you could see the casting #'s. All of the crate motors like the one in "Project Light Speed" with that part # were GTO LS1's. Probably surplus because they were coming out with the GEN lV's. All of the vendors had them for awhile there. There was a thread in, I think, Conversions and Hybrids Titled **Some exhaust manifold measurements** by *joshluther* dated 1/06/10.....it had some really good pictures of various manifolds and headers mounted on an engine on a stand along with some measurements at different spots. Well worth checking out. Ron

jweb47
01-21-2010, 04:22 PM
Maybe we're getting somewhere now...Thanks

brian g
03-02-2010, 06:51 PM
ls6 headers off a vette are the ones the article are talking about-I've got a borrowed pair in the garage right now-too bad they don't fit....

jweb47
03-03-2010, 09:22 AM
What year Vette?

WS6-R
03-04-2010, 12:01 AM
Ok, here are a pair of LS2 from my 2005 Corvette.
I messure the collector size and it is 2.5"
http://img28.imageshack.us/img28/6482/ls2manifolds.jpg
If anyone interested PM me before I put them in my WS6
:D

LS6
03-05-2010, 02:38 AM
informative information