[Biturbos4] All causes to turbo failures known?

[Keman]

: I have to respectfully disagree with Keman's opinion of the K04 turbos.
The
: K04s have a larger compressor and turbine housing than the K03s do in
: addition to the larger compressor and turbine wheels.  Its only slightly
: larger, but it is larger.  Also the compressor outlet is larger and
requires
: different (RS4) outlet piping.

Interesting. They looked identical to me, now I wonder if there are
different kinds of K04's ...

Any idea how much larger the outlet is? Are you sure it wasn't just
different outlet pipes leading to larger intercoolers? Unfortunately I did
not have time to measure anything..

However, ATP has been mentioning mirroring this information, as well as
suggesting using a pair of GT25s garrett turbos instead of K04's...  I'll
have to find out more about this.

: However, the most significant and important difference is in the shaft of
: the turbo itself.  The K04 has a reinforced shaft and should hold up much
: better than the K03 does.  Indeed the failure that you experienced with
the
: shaft would most likely not happen due to its more robust design (in
: addition to the fact that it is made to run higher boost levels than the
: K03s are).

Details... details.. reinforced is a very relative marketish sound.. :P We
talking larger diameter? A larger diameter will equate to greater bearing
surface speeds... (bad)

: The K03s appear to be somewhat underdesigned for the 2.7T motor, hence the
: failures.  Replacing them with K04s seems like a no-brainer to me, given
: that the cost is about the same and the K04s are much better suited to the
: engine.  And as of yet, no one has come up with a way to install any other
: turbochargers without relocating them and significantly altering the
intake
: plumbing ($$$).

What makes you feel they are underdesigned?

They work fine on a 1.8T, and a pair of them with the same volumetric
effeciency would support 3.6 liters with the same reliability. They're
feeding less displacement at the same boost levels on the 2.7. We should be
getting more reliability with less cubic inches to support, but we should
also get more lag if everything is equal...

You'd think I'd have access to tons of technical information on this. I
don't... :P

- Keman

: -Dave Pramanik