Making turbo manifolds out of cast iron

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Afternoon all.I did a few brief searches, but did not find much about what I'm aiming to do.Basically, I want to follow the work of AK Miller in the '60s and '70s and make a couple turbo exhaust manifolds for my truck and '67 Mustang.  The way he did it was basically by machining off the flange of the manifolds, then welding a mild steel flange onto the manifold.My concern is how to actually weld the cast iron.After a little bit of research, I've found that Lincoln suggests A) heating the material to a range of 500-1200 degrees and keeping it hot during the welding process as well as letting it cool very very slowly, or B) keeping it cool throughout and peening the welds to help prevent fractureshttp://www.lincolnelectric.com/en-us...on-detail.aspxDoes anyone have any thoughts on which would be better for the fabrication of a turbo manifold?I would think that with a surplus oven from a kitchen and a torch you could get the cast iron into that heat range fairly easily, but that's a lot of heat to be dealing with during the welding process.Of a secondary thought:I wondered about making a flange that had something similar to a neck going off the topside of it, then get a machine shop to cut a recess into the exit port of the manifold and inserting the pipe/flange into the manifold before welding it in place.My concerns with this are:How thick the material is at that pointExpansion rates of cast iron Vs mild steel (ie - would the steel expand faster than the cast, thus cracking it)Secondary to the above, how tight of a fit should it be, the tighter the fit the better to seal, but how tight does it get made to prevent expansion from borking the manifold.How deep I would go with the machined cutAny thoughts about this? Do I need to go into more detail, or do a drawing to show what I mean?It's a fair amount of questions, but I'll happily go into more detail about my plans with drawings or diagrams if I need to.The following pictures are someone else that has followed AK's path, but I can't get ahold of him to get any clarification.You can click on the pictures to see bigger versions
Reply:There are fillers designed for welding mild to cast, I cant think of their name right now but they do exist. Is it possible to make an adapter flange and bolt it to the existing flange? That would be the best way and would eliminate any differential expansion problems
Reply:Most modern turbo manifolds (i.e. anything from the 80's or later) are actually high nickel cast STEEL. They actually MIG pretty well with some preheat (propane or MAPP gas torch is fine, just spend some time heating the whole thing up) with just ER70S6. But the higher the nickel content in the weld, the less chance of cracking as it cools due to higher ductility. So something like 308L or 309L would be a good wire/filler to use to keep the nickel content of the weld up. I have no experience with really old cast iron, but if a turbo manifold is showing very little corrosion (like the one in your pic), there is very little chance of it actually being cast iron. It's likely a cast steel with some alloying elements to improve high temperature strength and corrosion.
Reply:Originally Posted by ironmangqThere are fillers designed for welding mild to cast, I cant think of their name right now but they do exist. Is it possible to make an adapter flange and bolt it to the existing flange? That would be the best way and would eliminate any differential expansion problems
Reply:A lot of the Cast Iron projects I repair are usually heated  and post heated on a BBQ gas grill. If you can take the heat and leave it turned up while welding. (I usually turn the burners down on low). If it appears to be cooling too quick or I am welding too much, I shut the lid and turn it back up to heat for a while, then finish the weld.I get a chance to study the rest of your post tonight at home and maybe/hopefully comment some more on your process.
Reply:Originally Posted by drujininA lot of the Cast Iron projects I repair are usually heated  and post heated on a BBQ gas grill. If you can take the heat and leave it turned up while welding. (I usually turn the burners down on low). If it appears to be cooling too quick or I am welding too much, I shut the lid and turn it back up to heat for a while, then finish the weld.I get a chance to study the rest of your post tonight at home and maybe/hopefully comment some more on your process.
Reply:If you do it cold that's the way. Short weld, move to an alternate place short weld, move and so on . pean between each move. If the manifold gets to hot to touch slow down or take a break,  the peaning re-leaves the tension while its cooling.  Ni-rod always runs best cold. Mac
Reply:My advice for welding cast iron, don't take anyones advice who hasn't actually successfully welded a fair amount of cast. This one topic where people who have never even done it will chime in like they have any idea what their talking about. It seems like few people have even done more than one or 2 cast repair jobs.Welding/Fab Pics: www.UtahWeld.com
Reply:Use the search function and look up the user Castweld's posts.  True artisan.  You will learn alot.  You may even want to PM him about your question.TA Arcmaster 300CM3XMT 304S22P12 suitcase feederX-Treme 12VSOptima pulserTA161SMaxstar 150STLHypertherm PM45OP setupStihl 020AVP, 039, 066 Magnum
Reply:Originally Posted by Drf255Use the search function and look up the user Castweld's posts.  True artisan.  You will learn alot.  You may even want to PM him about your question.
Reply:Originally Posted by Mr.AsaThe manifold shown in  those two pictures is not actually a turbo manifold, but is instead a Heavy Duty exhaust manifold off of a 300ci Ford I6 with the stock flange cut off and a turbo flange welded on (the stock manifold had a three bolt flange as shown here in this ebay ad http://www.ebay.com/itm/300-4-9-FORD...4a7326&vxp=mtr ).  These manifolds are somewhat rare and were last produced in (I think) '77.I would have to double-check with a couple of the more knowledgeable members of the Ford forum I am on, but I would bet that it would fall into that old cast iron category.
Reply:This guy is a whiz at cast iron manifold repair:http://imageevent.com/gmachine/manif...f6fxa1.goose_sGeorge Miller:  http://www.georgemillermachine.com/"USMCPOP" First-born son: KIA  Iraq 1/26/05Syncrowave 250 w/ Coolmate 3Dialarc 250, Idealarc 250SP-175 +Firepower TIG 160S (gave the TA 161 STL to the son)Lincwelder AC180C (1952)Victor & Smith O/A torchesMiller spot welder
Reply:Originally Posted by MikeGyverMy advice for welding cast iron, don't take anyones advice who hasn't actually successfully welded a fair amount of cast. This one topic where people who have never even done it will chime in like they have any idea what their talking about. It seems like few people have even done more than one or 2 cast repair jobs.
Reply:Originally Posted by OldendumThis guy is a whiz at cast iron manifold repair:http://imageevent.com/gmachine/manif...f6fxa1.goose_sGeorge Miller:  http://www.georgemillermachine.com/
Reply:There has been good advise given here, mostly in the form or people warning about information given from others that may not be experienced in cast iron welding. I will preface the information I will pass along by saying that as part of my job, I do fabricate prototype cast iron exhaust manifolds at an engine company.  From my experience doing this, there are a few key points specific to high temperature cast iron welding that I have found must be adhered to if the highest quality work is expected. 1-Do not mix alloys, meaning do not try to use a steel flange and a cast iron log section2-Use a filler metal composition that is as close as possible to the base metal, what this means is....stay away from the high nickel brazing/welding alloys commonly sold for cast iron electric welding.3-Pre and post heat is mandatory4-The best process I have found is the traditional O/A cast iron welding process, using a silicon doped cast iron filler ( I.E. Kastweld 111 etc ), and the traditional high pre and post heats with long cooling times.
Reply:Originally Posted by makoman1860There has been good advise given here, mostly in the form or people warning about information given from others that may not be experienced in cast iron welding. I will preface the information I will pass along by saying that as part of my job, I do fabricate prototype cast iron exhaust manifolds at an engine company.  From my experience doing this, there are a few key points specific to high temperature cast iron welding that I have found must be adhered to if the highest quality work is expected. 1-Do not mix alloys, meaning do not try to use a steel flange and a cast iron log section2-Use a filler metal composition that is as close as possible to the base metal, what this means is....stay away from the high nickel brazing/welding alloys commonly sold for cast iron electric welding.3-Pre and post heat is mandatory4-The best process I have found is the traditional O/A cast iron welding process, using a silicon doped cast iron filler ( I.E. Kastweld 111 etc ), and the traditional high pre and post heats with long cooling times.
Reply:Originally Posted by Mr.AsaAny way that I can check for sure on which I have?
Reply:Originally Posted by Mr.Asa#1 gives me trouble solely because I have no clue where I might get a cast iron flange, every one I have ever seen is some type of steel.I have a magic device that lets me talk to people all over the world.  I mostly use it for nonsense.This future brought to you by Tapatalk
Reply:Originally Posted by makoman1860This is where the machine shop comes it. Cast Iron is available in almost any size and shape you can imagine. I have actually found the scrap yard to be a good source of material to machine into whatever flanges are needed. If you are limited to what you can buy out of a catalog, then you will be limited in the quality of the finished part.
Reply:Assuming you're using a T3 or T4 flange, 1/2" is a good bet when it's stainless or mild steel. Cast iron has lower mechanical properties, especially at temperature, so I'd be wary  of just threading into it with a stud. Especially due to corrosion. For studs, go straight to high temp alloys like A286 or Inconel 625. Full-Race.com has a set of studs and nuts that will last forever, and still disassemble (silver coated nuts, A286 studs). I'd still get a test piece and weld a stainless flange to it and see how it behaves. You might be surprised at how well it does as long as the carbon content of the cast iron isn't super high. Use a rod like 309 with nickel in it to improve high temperature mechanical properties. Don't be afraid to put some extra gussets (maybe 3/16" 304 or 316 bar) on the long axis of the flange as well. More weld area is always better in a situation like this.
Reply:Quote: "My advice for welding cast iron, don't take anyones advice who hasn't actually successfully welded a fair amount of cast. This one topic where people who have never even done it will chime in like they have any idea what their talking about. It seems like few people have even done more than one or 2 cast repair jobs." Well you asked on an Open Forum.I have welded and or brazed a fair amount of Cast Iron over the 35 plus years.From cracked engine blocks, cylinder heads, farm machinery parts, manifolds and transmissions at a rate of 3 to 4 per year.Even silver soldered a few pesky spider cracking heads just to keep the coolant in.So I posted how I do it.