Welding Cast Iron

Asa

Asa

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Ok, I've heard a lot of stuff about fabricating a turbo manifold out of a regular stock exhaust manifold by just welding a steel flange onto the manifold. It sounds like a pretty decent, and solid manner of going about it

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 fractures

http://www.lincolnelectric.com/en-us/su ... etail.aspx

Does 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.
 
I have done the cool type welds with peening using an arc welder on small area repairs and had good results during the warm weather months. For the turbo flange though I think the preheated and slow cool down would be best way to go.
 
Im not a Pro welder, but i have done a lot of stick welding. Have repaired more than a few exhaust manifolds. I like using Stainless steel rod, ( makes ya look good) works great for welding steel to cast iron. Yes on the pre-heat, i use my cutting torch. In the dark, it would be a slight glow at most. How good the cast is makes a BIG difference on how well it looks. I know Asian manifolds dont weld as good. ( they use recycled iron ) practice on a junk one first. If you can stick weld, you can do it.
 
I was thinking about how to do a turbo manifold.

I wondered about making a flange that had something similar to a pipe 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 point
    Expansion 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 cut

Any thoughts about this? Do I need to go into more detail, or do a drawing to show what I mean?
 
I have questions to yours ? Do you have a 200/250 ? or a 240/300 Truck ? since we have both here. picture/drawings, always good. From made up Turbo Manifolds i have seen. The amount of steel flange welded to cast manifold, doesnt seem to be an issue. Concider mounting Turbo to engine & running pipe & flex pipe to turbo? what im thinking for my future 300 Truck turbo. Mount turbo high on drivers side of engine. Use Fuel Inj. exhaust manifolds make a Y pipe, with a flex pipe on one side. go under engine, turn up into flex pipe, then to turbo. others have done it. If you maybe loss too much heat, you can wrap pipes & turbine housing. to adjust tune, turbo lag. a lot of fast cars with turbos mounted in rear, something to think about.
 
I think they are similar in expansion rates of steel vs cast. Not scientific but a few times used a cutting torch to melt and blow out the center of old bolts or studs broken off in cast, if careful can be done without damage to cast part. Think you would want a min. of 3/8 or even a 1/2 inch thick for your turbo flange like if you were going to tap threads into it.
 
X2 on that. alot a turbo flanges on E-bay, all types. most look nice & thick, as they should be. Dont think a welded flange to an exhaust manifold most the time would be an issue. ( Drag racing, street car) But in like Road racing, or heavy long pulling, where your Exhaust Gas Temps are higher for longer. The weld up would need more attention.
 
Over at the HAMB, when discussing cast iron welding someone always mentions "muggyweld" (sp) - ? , rod specifically for purpose?..

... how about MIG welding cast to mild?...


'hope to weld up a "J-Pipe" for stock exhaust maniflod to turbo flange.

thanks
 
powerband":2jmv0n3b said:
Over at the HAMB, when discussing cast iron welding someone always mentions "muggyweld" (sp) - ? , rod specifically for purpose?..

... how about MIG welding cast to mild?...


'hope to weld up a "J-Pipe" for stock exhaust maniflod to turbo flange.

thanks
Click to expand...
Never heard of muggyweld, but I'll look into it.
As for mig, I'd love to as I'm much better with that than stick welding, but from everything I have read it won't work as well. I have no clue why.

Maybe I need to find a welding forum to talk to someone about it?
 
I would never weld a flange to a stock intake manifold. Its not that it can't suceed, its just unless the manifold is factory designed in ductile iron, then your better off continually cobling up a bolt on adaptor to the stock exhast flange. That way everything is simple. Ford Explorer engines used exhasts in mandrel bend 90 thou thick steel, and you can section one of them up, hook up a J tube, and your work of art is an instant pre production prototype.

Ak Miller used to cast special exhast adaptors in steel, and make them look sexy and work even better. For me, I'm not quite as certain that changing a stock components is the right first step, I believer the way forward is always to adapt.

Especially when in the case of the last 3,3 and 4.1 engines from 1980 to the last 3.3 in the Fairmont and LTD, there wasn't an easier turbo manifold flange to bolt a combined steel plate and turbo flange on than the 4.25" four bolter. Huge, low restriction, and, above all esle, simple as pie.
 
I had thought of dropping the $$$ for one of the 300's HD exhaust manifolds and making a very short intermediate pipe that I can bolt and seal to the stock flange and weld the turbo flange on the other end. It would still sit very close to the exhaust ports on the head and you could always bend the intermediate pipe a little in any direction for fitment. Maybe just get a prefab, mandrel bent u-pipe and cut it off where you want. This would offer up a great place to mount an external wastegate as well if the turbo doesn't have an internal one.
 
I welded flanges to the EFI manifolds on my 300. The flanges came from ebay. I cleaned the manifold and flanges, C-clamped them together and put them in the oven at 500 degrees for an hour.

I used NI-55 rod and welded the first manifold flange from 2-4:00 and from 7-10:00 and put it back in the oven while I did the other manifold. Put the second manifold in the oven and finished the weld on the first manifold and back to the oven it went. I then did a final 360 degree pass and put them back in the oven and turned the oven off and left until cool.

Over 10k miles and no issues so far.

Miller EconoTwin and the amperage recommended for the rod-
 
I've seen what happens when you don't prep the metal properly. Just slightly off topic, but my other hobby is two cylinder John Deeres. I have a '31 GP to restore. The *cast iron* head had a crack in it. The previous owner welded. It's now cracked worse. So I had to go buy another head. :banghead:
 
a few more 2 cents :

I could probably weld a flange to a cast manifold on a bench and have it look good, but after installing, heat cycling may change things. I don't want to complicate my turbo-novice startup and tuning worrying about unseen weld-cracks after Turbo install. I had discussed reversing a set of HEaders like the V8's', but turbo-guru's insist on proximity to the thermal dynamite cyl's exh ports is better . I'm still mocking up but leaning toward simple short J-Pipe with Turbo in accessible Battery area:

. . .
.

... ideas welcomed... 8)



have fun
k
 
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