tom mayer wrote:

A really simple way to avoid hurting the turbo at start up or shut down is
to use a manual wastegate.  The wastegate should be open when you start.
You open it fully during let down for landing, assuming you have enough
power to make a go round safely without boost.  With the wastegate fully
open, at least on the home made turbo set up I have been running on my
Lycoming powered Mustang II, there is insufficient exhaust through the
turbine to spin the blades.
    This way you have oil flowing through the turbo long before you start to
spin it and you have oil flowing through it long after you have stopped
spinning it.  I have some 400 hours on a system like this, with absolutely
no coking or any other problems with the turbo.  Of course I am using the
turbo only to normalize, the engine without turbo produces more than ample
power for take offs or go arounds at any airfield under 6000 msl.  My
experiences years ago with retrofited RayJay manual wastegate systems on
C-180s and Comanches and Twin Comanches dovetailed with what has happened on
my Mustang installation. Tom Mayer

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