Thread: Cast iron expansion

Bit like the chook and the egg thingy Manifold heating and resulting expansion is a very complex scene. Now if the exhaust manifold was a nice square piece of cast iron with a nice round,central smooth sided hole through it, things would be great! every part would receive the same amount of heat with the resulting same rate of expansion!
However manifolds are not neat pieces of cast iron. They have all sorts of curves, right angles, thin bits, thick bits and it goes on, the result of manufacturers cutting corners as much as possible . So no 2 will perform the same, even 2 for the same engine can vary in the castings.
I suspect the shape of the TD5s is part of the problem, Long, tapering,with resulting difference in thickness and so heating variance and so resulting expansion rates. The V8s is short, and to an extant the same shape front to back. This will result in a more even distribution of heat, even though far from ideal.
NOTE This is only my thoughts on a complex situation.
Cheers Scott