I have never seen a rotor housing have TIG welds. Does anyone know why they would do such a thing? This came off j-spec twin turbo. The center iron also has unusual writing on it also.

 

If I were to take a guess, when they make rotor housings, they don't make them one at a time. They are probably all welded together in a couple spots, run down a line, and when they are finished are cut apart, that one was probably just one on the end

course I could be breathing some very funny dow air and it making me think loopy

 

the castings are never perfect and they do welding to repair some of the hollow areas.

i often wonder how many brand new housings actually wind up in the scrap pile and need to be totally recast because i see welds on them quite often.

 

Your knock sensor looks rough!