When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Due to the overwhelmingly different responses I've read when the question "What truck manifolds are really made of" is asked. I have decided to get a chemical analysis done. It will take a few days to get the results back and it's close so no big deal.
Before I spend the money on the test does anyone have any definitive proof of what they really consist of? Did GM switch up materials for certain years? It's there anything else i should be considering to insure the test is accurate and consistant? The manifold I'm sacrificing is from a 2001 5.3L truck.
Results:
So what this means is that 94.5% of these manifolds are Cast iron. These are NOT a "cast steel" most of the steels we use are less than .400% carbon and have far less silicon. On paper these manifolds are a welders nightmare. It truly is amazing the success we have had. IMO a high nickel content welding rod/wire is your best bet here.
I'm ready to put this one to bed. I agree they weld super nice but look an awful lot like cast iron. Mine cracked a bit during welding so it will be nice to see If that is consistent with cast steel like cast iron
I mig'd mine. The pass side took a fairly significant mod to get the outlet to point straight ahead on my Nova.
When I had it off to replace head gaskets, I noted a crack right through the weld where the pipe met the manifold.
I ground the weld out, preheated with acetyline torch and re welded. I'm not going to be surprised if it cracks again. Just a lot of stress there due to the mod required.
You can hear the thing contract as it cools after shutting the car off and it's sitting in a quiet garage.
I mig'd mine. The pass side took a fairly significant mod to get the outlet to point straight ahead on my Nova. When I hat it off to replace head gaskets, I noted a crack right through the weld where the pipe met the manifold. I ground the weld out, preheated with acetyline torch and re welded. I'm not going to be surprised if it cracks again. Just a lot of stress there due to the mod required. You can hear the thing contract as it cools after shutting the car off and it's sitting in a quiet garage. Ron
Was the turbo supported? Or did the header bolts take the load?
I used 309 rod no preheat and it was cracking as soon as I pulled the torch away. Next time I'm going to try an Inconel 625 filler rod. We use it at work on the turbines to weld dissimilar metals (carbon to stainless) as opposed to 309 which is crack prone with big temperature swings.
I used 309 rod no preheat and it was cracking as soon as I pulled the torch away. Next time I'm going to try an Inconel 625 filler rod. We use it at work on the turbines to weld dissimilar metals (carbon to stainless) as opposed to 309 which is crack prone with big temperature swings.
Did you ever run them with the 309erl? That's what i used and I'm almost positive they are going to crack under load
I miged 309erl and heard micro cracking right after. A few passes of the grinder and another layer of weld went on so we'll see what happens. As of right now they have seen about 30min of idle time.
Unrelated to truck manifolds, but a cheap SS alternative is out there.
The 98 LS1 manifolds use a 0.8mm thick 309SS inside layer. And a 1.8mm thick 409 SS outside layer. There is a 3mm airgap between the two walls which is filled with a glass type insulation. (dual layer on pass side only)
Migged these w/ 309L wire and tri-gas. Turned out great. Been kicking for about 3 years now. With zero sign of cracking. I'm pretty hard on them with 60+ psi of back pressure and rigid mounted turbo/motor mounts.
Last edited by Forcefed86; 10-01-2014 at 02:05 PM.
09-30-2014, 12:32 PM
