Re: bypass valve presure openings

[Brendan Rudack <rudack@umcc.umcc.umich.edu>]

On Wed, 28 Jan 1998, Avi Meron wrote:
> flow to turn the turbine), it only coasts when you let go of the pressure /
> throttle, also it is NOT vented to the atmoshere, it is vented to the air
> box in.

Avi, I was referring to Gary's explanation of his friend's 4ktq which is
being run with a blow-off valve and no wastegate. Ok, Throttle plate
shuts and blowoff dumps excees pressurized air,  wouldn't there be a
momentary turbo overspeed until pressure from last few piston strokes and
exhaust manifold pressure clear out through the turbine since there is no
wastegate? And might it be exagerated when the blow-off opens reducing a
lot of the resistance on the compressor side?  Or are the pressures in the
EM too small to do that to a turbo spinning at ~100k rpm's?


Brendan Rudack