What would cause this?
The mods to the engine are M2 Stage III, Down Pipe and Racing Beat exhaust. All else is factory stock. The exhaust manifold is undamaged.


I have another set to turbos but don't want the same thing to happen....

 

Heat

 

OK I guess that's obvious... Is this a common situation or do I have a lean condition or something else wrong going on?

 

Depending on the age of the turbos, it's pretty common. i.e. if that happened within 10k miles, that would be a problem.

 

Here is mine at 100K running 12 psi making about 300rwhp on a PFC, m2 SMIC, dp and PFS catback. One thing I noted was that the spool up on the primary was sluggish, transition wasn't that abrupt any longer. But at full boost, it ran fine.

 

Holy crap, time to stock up on good condition stock manifolds... lol

 

OK Looks to be common for high milage engines. Mine has 128,000 miles on it. M2 did their Stage III when the car had 40,000 miles on it. BTW I noticed the same symptoms.....
Thanks.

 

This is the result of thermal cycling and the complex nature of the casting. Unequal rates of expansion/contraction throughout the casting result in small cracks which erode over time due to the concentration of heat at the edges [of the cracks].

The Turbo Control Valve flapper can no longer seal effectively, hence your loss of low end performance as some of the exhaust flow is bypassing the primary turbine.

 

wow after seeing that im kinda glad i have like 4 sets of bad turbos but with good manifolds lol

 

Here is my 2nd set with 40K on it at 12 psi, 311 rwhp. These housings don't last long if you are over 300 rwhp for more than say 40K on them.

 

Here was mine at 94,000 when I rebuilt the engine. lol....I remember posting this pic all in a panic with a "OH MY GOD....LOOK AT THOSE CRACKS!" wringing of hands.....