mild steel to cast manifold?

[bigwillyz]

hi

need to weld a mild steel outlet of off my cast exhaust manifold.

i was thinking of heating it up with the o/a then miging it
but i think it might crack being a manifold.

would brazing it work?
or how about tig?

why do i start these things

thanks mike

 

[dopplershift]

I'm just guessing here really, but: TIG brazing? Or O/A brazing? I'd imagine that you'll want to cool it down as slowly as possible... being thin sections, this could be difficult. May need the play the O/A over it every couple of seconds, slowly getting less and less frequent, over the course of 30mins or more?

Are you sure you need to weld it? Can we have more details of what sort of mild steel outlet you mean?

 

[bigwillyz]

ive put a bigger turbo on my volvo and it doesnt have
a internal wastegate so ive got to use a external one.

i was making a tubular manifold but the bends l had bent
were a bit crap so put the idea on hold as cant afford
a load of mandrel bends yet.

so im having to use the original manifold

mike

 

[TechnicAl]

ideally you need a pure nickel wire / rod but they are expensive, probably about £50 per Kg.

You need to keep it cool, little short runs and peen, allow to cool and start again.

but you might get away with mild steel. Unless you get it red hot, preheating wont make much difference so keeping it as cool as possible is the easiest way.