what are the 98-99 manifolds off of ls1 camaros made out of?cast iron or steel?can they be extrude honed either one?

 

I have a set of 98 manifolds that are made from two stamped steel parts welded together. I've read that all 98-99 manifolds are stamped steel, 2000 and later are cast iron.

 

Run long tubes. your motor will thank you

 

They're SS and a tube within a tube. The outer tube is two halves welded together over regular drawn thin wall tubing. No honing with these....

 

Well,longtubes are just stupid pricey for the s10's. The 1 1/2 tubes are wothless prettymuch.So now everyone is saying the manifolds cant be exrude honed?now what?

 

There's nothing really wrong with the stock manifolds, but I suppose what you want from your conversion is what will dictate what you end up with. I'm going for the 'stock' look in my engine compartment and with ~ 300hp from the stock engine it will be more than enough for me,at least to start with. The stock, albeit modified to fit my application, flows fairly well.... shorties will give you a little more power than stock if you want that route.

 

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There are supposed to be two construction techniques.

Early LS1 camaros supposedly had stamped stainless exhaust manifolds, made of several pieces (inner and outer skins, inside and outside, which should be 4 pieces total). I've never seen a set, and had also heard that the stamped stainless was only used on the early C5's ('97 and early '98). I have seen pictures of the C5 manifolds, but not the F-body version, so whether they exist or not is a question for me. If they do exist, they cannot be extrude honed (because its two thin pieces of stainless (probably 18 or 20 ga) with an air gap between the pieces, there just isn't enough material to erode away).

The later LS1 camaros came with cast exhaust manifolds. Depending upon year, you may or may not have the EGR boss tapped. I don't know what material they were cast from exactly. Ground and cut like cast iron, but I welded (using MIG) them up (Air Injection holes, some extension made of 2.5" tube, cut off the EGR boss and replaced with a section of 2" black steel pipe) and the manifolds welded great. I don't have that many miles on them, so I guess I'll have to see whether they hold up or not (I hope they do) to the heat / cool cycling. These manifolds could be extrude honed, because they are solid with fairly thick walls (1/4" or so). And they would see a benefit from it.


Long tubes would be a great option, but they are some serious money and not available for all applications.

For my particular application (a 4wd S10) I'm not 100% sure there is room for a decent set of long tubes (tube od and primary length). There's alot of stuff to avoid (framerails, front diff and driveshaft, steering shaft, inner fender, brake lines, etc). Most of the dyno tests I've seen indicate that 1 7/8" long tubes do the best overall (which is contrary to old SBC stuff which says 1 5/8" for the street, maybe 1 3/4" for street / strip use). I stuck with manifolds since I wanted to get the truck running as quickly as possible, didn't have the $$$ to buy a set or the time to build a set. Maybe somewhere down the road I'll see about building a set of long tubes. Or maybe I'll add boost or a shot of N20 instead, I think I'd gain more power.

'JustDreamin'

 

I have stock 99 manifolds on mine...and they flow great really. I mean as well as the 1-1/2" shorties do i would say. Only real way to get more power....is to make your own.

 

You can find used shorties for under $200. I don't know the cost of extruding a cast manifold. I sold the set of JBA stainless headers I originally had for $215 shipped.

 

Well, at this time I think I'll just use the stock manifolds compared to the 1 1/2 tube headers that are out there.....

 

Get some 2000+ cast manifolds, port the hell out of the head side and the downpipe end, get them extrude honed, and coated if you're really serious and you'll likely make better power than most of the shorties on the market.

 

The cast manifolds just wont work...cause the flange hits the frame..and you cant cut it off and weld extension pipes to it to make them work like you do 98-99 ones.

 

Just don't tell the set of '02 cast manifolds that I did that to. They're on the truck, and I don't want them to know they cant be made. (truck runs pretty good too).

I am a little concerned about long term life, but man, whatever they're cast out of, it welded great.

'JustDreamin'

 

If you want a set of 2000 manifolds, I'll sell you the ones I have laying in the corner, cheap. You will have to replace some studs.

 

I shouldnt have said they WONT work...they will, but yes be concerned about long term durability. You could make them very safe by putting in a flex pipe so the manifold doesnt take any stress...but that cast metal weld will not hold if put under any kind of stress. As I said...i shouldnt say WONT work...but in my opinion I wouldnt do it. I wont trust any weld to anything cast and porous as they are.

 

people used to tell me that I couldn't weld mild steel tubing to CrMo either. Just gotta gas weld it and use wire coat-hangers for filler rod. It'll work until it doesn't. Perfectly appropriate for an old go-kart or beater.

 

so I'm wondering what is the HP limit on the manifolds?I know they cant let out 510 HP,I MIGHT just not put the heads on and the cam in right now until I can figure out the exaust situation,it would prolly run to warm anyway with the manifolds with the bolt ons???

 

If you're planing on ~500hp then you'd better go to long tube hedders, even if they need to be custom made.

 

I think Current Performance is planning on making some mid length 1-3/4" headers soon for the S-10 conversions. I saw that somewhere the other day.

 

The manifolds on my 2003 5.3 truck engine are cast steel not cast iron. If the manifolds you have are fairly new they will be cast steel too. I had to cut the flanges off and turn them to fit my project car. You can heli arc them with
inconel welding rod.