[s-cars] installing a hybrid turbo

[Joshua van Tol]

On Aug 1, 2006, at 9:31 AM, Postupack, Jeff wrote:

>
>
> 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
>

Journal bearings also have more friction, hence ball bearing turbos  
typically develop boost sooner, all things being equal.


>
> ------------------------------
>
> 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
>
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