A question for anyone with turbo charger experience. The manifold on my ZDJL (a custom job with 1.75in runners) which has been in use for about 5 months has developed several cracks around the weld where the flange meets the exhaust turbine housing. It also quite literally blew a hole in the same area leaving a gap about the size of a 5c piece. The hole was subsequently welded, and I noticed the cracks appearing about two weeks after the hole was repaired.
The only thing I can think of which may be causing this is excess torsional movement of the motor itself. The exhaust system seems to be fixed to the car rather than hung which affords little in the way of flexibilty which would mean that the manifold is acting like an additional engine mount, and eventually something has to give. Or; a simple problem of temperature fluctuation causing rapid expansion and contraction of the manifold.
I know that welding makes the metal brittle and prone to failure but it seems odd that these problems would manifest themselves all within the same short period of about 2 weeks. Can any of my fellow frogs offer any advice as to whether I should try different runners with thicker walled steel or should I investigate the possibilty of a more liberally fitted exhaust and try to brace the motor to avoid any flex?