Received-SPF: pass
 receiver=logan.com; client-ip=209.225.28.215; envelope-from=cardmarc@charter.net
Message-Id: <44039q$120qeb5@mxip15a.cluster1.charter.net>
From: <cardmarc@charter.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Subject: turbo PRV's
Date: Mon, 13 Jun 2005 12:15:00 -0400
MIME-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit

Whoooah. All serious aircraft that have turbos have a "PRV"-pressure relief valve on the intake manifold, set to open a few inches above the max boost level you contemplate on maintaining (turbo-normalized models). They are able to maintain sl pressures in the intake at elevation, so they are referenced to know the difference. The one I'm using opens at 35", even if at 20,000 feet.
Marc Wiese
> 
> I also understand the blow-off valves are useful in car applications, where
> the driver will shut the throttle suddenly after a period of high boost. The
> turbo can not shut down so fast and the compressed air has no place to go.
> The valve than releases the air out to prevent damage. I don't see why we
> need blow off valve in aircraft?
> Bulent