Originally Posted by Rusty

To weld something like this. I would drill a hole at the ends of the crack. Grind a V in the crack about 3/16" wide. Bolt the manifold down so it doesn't move. Preheat the manifold to about 700deg. Tig weld it with something like Ni-Rod 55. Weld only one inch of the crack at a time. After each stitch. Peen the weld with a ball-peen hammer. What is causing the cracks is unequal heating and cooling of the manifold. That turbo heats up slower then the manifold, and cools off slower then the manifold. I've welded cast iron in the past with the company I used to work for with great results.