[s-cars] installing a hybrid turbo

[Postupack, Jeff]

Further to what  Dave wrote.. 

I consulted with a machinist who worked in the aircraft business his
entire life.
Having seen ball bearings, bushings in various applications.he told me .
"A journal bearing  is a cylinder which surrounds the shaft and is
filled with some form of fluid lubricant Journal bearings can have
unlimited life, compared to a ball bearing."
->. For the more complete write up, seek
http://www.reliabilitydirect.com/appnotes/jb.html

He (the machinist)  also commented that journal bearings are much
tighter tolerances composed of particular material much better suited to
the 
Hot side and cold side of the turbo charger.,  than a ball bearing will
ever be.

All the fascination with ball bearings may be misguided for a long life
expectancy,  turbo application.

Truth be told a journal bearing can be machined to very close fitment,
which means the shaft will not wobble.
Isn't that what the Audi R&D actually specified also?

Which means when I get around to selecting a turbo, for long life and
higher boost, it shall have a journal bearing.

Posto


------------------------------

Message: 2
Date: Tue, 01 Aug 2006 00:48:31 -0400
From: djdawson2 at aol.com
Subject: Re: [s-cars] installing a hybrid turbo
To: calvinlc at earthlink.net, tedebearp at yahoo.com,
	james.pasqualoni at gs.com
Cc: s-car-list at audifans.com
Message-ID: <8C8833CDFAF9FD8-D28-A04D at FWM-D43.sysops.aol.com>
Content-Type: text/plain; charset="us-ascii"

1) the journal bearing units are inexpensive
2) I haven't seen the journal bearing units fail (genuine Garrett, not
ITS, etc...)
3) I *have* seen many of the GT units fail
4) if your hp goals are 400whp or less, why bother with a ball bearing
unit?
5) a 50 trim allows a lot of boost at low rpm without surge issues
6) the GT units seem to be much more prone to surge
 
IMHO, there's a lot of trouble-free hp available from a 50 trim T3/T4.
Great drivability, low boost threshold, low cost.  In fact, the 50 trim
compressor is about the most versatile thing I've ever experimented
with.
 
OTOH, I run a 30R... but I wanted "more."  But, as a result of this
choice, I'm on turbo # 2 in 50k miles, and under certain circumstances,
I do have surge.
 
Dave