Never saw anyone preheat an exhaust manifold.
You never ran a turbo to see what happens to the manifold either on your super welded split manifolds.
Why use any special nickle rod since any dumb a$$ can weld cast iron.
That is part of your prep work, getting the correct rod( need to do the research) for the job at hand.
No reason to reinvent the wheel, if there is a turbo exhaust manifold available that is made for a turbo & will give you a much easier time to install a turbo y not buy it & you can keep your chopped up manifolds for your N/A engines.
No need to risk some weld slag,/debris to loosen up inside the manifold & take out your turbos turbine wheel, right?
You get what you pay for when it comes to a turbo manifold, looks, long lasting, & better performance, ease of installation, etc, etc, etc...
There are cheaper alternatives, but I have learned a long time ago, if there is a great product out there & I could not afford it, I would just save my $$$ until I could buy it, some things you can skimp on, but some areas you should not skimp on when it come to a turbocharged engine build IMO.
All you need is a 292 2.5" exhaust manifold for $60 or pay someone to cut up some manifolds, pay someone to weld it, think that will cost more than $60 , where is the savings?
Or you could buy a welder, buy some manifolds,, hack saw, sawzall, band saw, chop saw, it is all going to cost you in the end, & in the end, it will most likely look like a hack job, if you have no experience, it aint rocket science, ha! for some people, turning a screwdriver is rocket science.
It's just like telling someone to use there common sense, ha, some people just do not have a clue & have no common sense.
I paid $120 for my SPA manifold, because I know someone that lives in Brazil.
Backyard turbo builds:
http://www.youtube.com/watch?v=TCSQr3eRQcAhttp://www.youtube.com/watch?v=KFajr4QgARkClean install here w/a SPA manifold:
http://www.youtube.com/watch?v=cTS0smggZnETake your pick.
Pretty basic turbo ,low dollar build, use a 292 exhaust manifold, make a "J" up pipe to the turbo., the rest is up to you, blow through, draw through, not sure which way you want to go.
Simple draw through.
Beater has pics of this type on his 292, Beater?
SPA manifold ready for a turbo, & also ready to bolt on a wastegate.
MBHD