CorvetteForum - Chevrolet Corvette Forum Discussion - Factory Exhaust Manifold Collector Size

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Factory Exhaust Manifold Collector Size

Ive tried searching but heres the question.

Im not looking for any fancy exhaust manifold just to replace the original one due to a exhaust leak cause i snapped the bolt off..... So, Im going with a shorty header, which i believe is the same size as factory. I noticed for the collector option their is a 2 1/2 and a 3. Which one is factory size? And does anyone knoe any company that has them for cheap :ack:

93 LT1 Auto

Quote:

Originally Posted by TheKid!! (Post 1577661902)

http://auto.howstuffworks.com/1993-corvette1.htm

Doesnt say what the exhaust manifold collector size is. I need the size above the cats. So its exhaust manifold then bolted to pretty much the cats.

http://www.summitracing.com/parts/PSM-70-1340/

2 1/2 Collector

http://www.summitracing.com/parts/DOU-D3330-R/

3 Collector

Which one is stock collector size

2 /12, I am 99% sure. for a quick confirmation call this # (631) 841-0779
The vette Dr's. On my 87 it is 2/12 inches however.

Quote:

Originally Posted by TheKid!! (Post 1577664057)

2 /12, I am 99% sure. for a quick confirmation call this # (631) 841-0779
The vette Dr's. On my 87 it is 2/12 inches however.

sorry i havent been on but ill give them a call. i thought people would have answered it already lol

Ok that didnt work. Someone has to knoe.....!

I have two sets off a 86 350. One is like chrome and the other is used. I took them off to put the chrome on and then bougth some headers.

Taken from
http://forums.corvetteforum.com/1558875229-post11.html

Quote:

Originally Posted by VetNutJim (Post 1558875229)

NOPE!!! I'm just WRONG as HECK.Those are just like the ones I have.... I just remembered them WRONG.
I got to be getting that oldtimers disease.
#%@%!@$ I hate it when I'm wrong. :) :)

Mia Culpa,Mia Culpa.

I just got back from the garage where I checked and MEASURED the port sizes on the LT1/LT4 exhaust as well as the L98 exhaust manifolds.

Here's the LT1/LT4 exhasut port sizes.
Yes, there is a GIGANTIC middle port that would be split by the seperator in the head....

LT4/LT1 both end ports... 1 7/16 x 1 9/16
Middle Port.....................1 9/16 x 2 1/2
Exit Port at the collectors.... 2 1/2"

L98 ALL ports 1 1/4" kind of square... round edges in the corners
Exit Port a the collectors.......2 1/4"

L98.....There are TWO of the tubes (on each header) that are squished down looks like to clear the heat shields

The LT1/LT4 exhaust manifolds DO LOOK, TO ME like they would flow a little more than the L98 shorty manifolds.
A LOT more maybe????

The L98 headers are poorly made with a lot of weld covering the port in the exhaust manifold. I don'y know how much there is to gain by cleaning that up but I did it to mine. Probably about 1/2 HP gain for all 8. Not worth all the grinding and sweating, LOL.
The LT1/LT4 exhaust are a lot nicer made piece IMHO.

The LT1/LT4 exhaust manifold HAS a center port 'injection' fitting for the A.I.R. system. I only checked one of mine but I think they have 'one each' of these holes in both manifolds.

Knew I had those back for there for something, guess I just forgot what they looked like and I still don't remember why I have them. Must's been planing something for my L98.

Sorry for the erroenous info above guys. Memory ain't working good as it used'ta.

OH, head port exit sizes..I almost forgot.... I JUST measured these also.

128 Head Exhaust ports..... 1 3/8" x 1 5/16" 'Square" ports....rounded a little in the corners
113 Head Exhaust ports...... 1 1/4" x 1 1/4" "D" shaped ports.

Again, sorry for the wrong info I posted, guys.