[Diy_efi] This turbo assist stuff, suggestions

Bernd Felsche bernie at innovative.iinet.net.au
Wed Jan 1 10:17:27 GMT 2003


On Tue, Dec 31, 2002 at 09:17:15PM -0800, efi student wrote:
> Got data?  I can get all the anecdotal evidence I want from lots of
> testimonies, but I can get the same thing for Prolong or Slick 50.

Ball-bearings indeed do have lower friction than under-lubricated
hydrodynamic bearings.


> If you think ball bearings have less friction than a properly
> oiled plain bearing, you're kidding yourself.  

Unless you're running some sort of "oiler", the turbo spinning down
after the engine is turned off will be withough circulating oil - so
the bearing friction will be high and wear will also be high. A ball
bearing requires very little oil in comparison; it only needs the
oil to wet the surface of the races.

And when starting, you have a similar situation; hydrodynamic
bearings dry until enough oil flows through the bearing to allow it
to work.

> Plain bearings have some pretty significant advantages over ball
> bearings.  

The main reasons being that they are more quiet, cheaper to build
and maintain.

The use of ceramics BTW reduces expansion and hence the loading on
the balls and races... that's the main advantage for a turbocharger;
the housing and bearings typically being made from different
materials. 

Oil-flow can, OTOH be used to minimise temperature fluctuations when
the engine (and oil pump) is running; but is doesn't resolve the
isssue of bearing pre-load to accommodate cold, warming, hot and
cooling conditions - so the design of the bearing housing is
critical.

-- 
/"\ Bernd Felsche - Innovative Reckoning, Perth, Western Australia
\ /  ASCII ribbon campaign | I'm a .signature virus!
 X   against HTML mail     | Copy me into your ~/.signature
/ \  and postings          | to help me spread!

_______________________________________________
Diy_efi mailing list
Diy_efi at diy-efi.org
http://www.diy-efi.org/mailman/listinfo/diy_efi



More information about the Diy_efi mailing list