Originally Posted by E92Fan
It would be great to use a ball bearing housing, but unfortunately there's no option to fit a ball bearing cartridge into a TD03, let alone one that fits the size of shaft used in there (small) in comparison to the Garrett ball bearing shafts. So the only feasible options brings us back round full circle to the Garrett CHRA with the hefty price tag!
The other concern is that, without looking at an ASR or Racing Dynamics turbo which both use a Garrett CHRA, the guys at Turbo Dynamics are curious as to whether oil and water lines have been fitted because the work involved to do so is apparently immense and extremely costly. Visually it appears that those turbos are using old T25 bearing housings that don't run any water cooling. If there's no water cooling, those bearings will cook themselves pretty quickly!
This is just purely conjecture based on a brief visual analysis of a picture. It could be that ASR have fitted water and oil lines, in which case the concern about cooling is negated.
On a side note, with regards to the wastegates on the BMW turbos, the arm and valve assembly are specific to these turbos so what has been done is the new bushes have been machined slightly undersized to accommodate the arm and valve that have been modified to fit.
The ASR or Racing Dynamics are ONLY oil cooled if i am not mistaken.