X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fed1rmmtao106.cox.net ([68.230.241.40] verified) by logan.com (CommuniGate Pro SMTP 5.3.9) with ESMTP id 4464897 for flyrotary@lancaironline.net; Mon, 13 Sep 2010 09:18:55 -0400 Received-SPF: none receiver=logan.com; client-ip=68.230.241.40; envelope-from=alventures@cox.net Received: from fed1rmimpo03.cox.net ([70.169.32.75]) by fed1rmmtao106.cox.net (InterMail vM.8.00.01.00 201-2244-105-20090324) with ESMTP id <20100913131817.KWRH3042.fed1rmmtao106.cox.net@fed1rmimpo03.cox.net> for ; Mon, 13 Sep 2010 09:18:17 -0400 Received: from BigAl ([72.199.216.236]) by fed1rmimpo03.cox.net with bizsmtp id 6DJJ1f00G56cS2o04DJJFF; Mon, 13 Sep 2010 09:18:18 -0400 X-VR-Score: 0.00 X-Authority-Analysis: v=1.1 cv=e4n1ZjYY/MidH6WTRS5qGD+cSaIt2UqZNViAts1RHs8= c=1 sm=1 a=Y_lblG3xEFsA:10 a=lN8H/RjlhkCyIsyuOn2r7w==:17 a=Ia-xEzejAAAA:8 a=NLMMtyd2XH1mSFXjKuwA:9 a=5PcOS27Gv34YiIg6ckwVvxiLIi8A:4 a=CjuIK1q_8ugA:10 a=EzXvWhQp4_cA:10 a=yMhMjlubAAAA:8 a=hyl0EP82R6wo_Gy9iQwA:7 a=0Y4uHP-T0Cm4I-b6lhELXv65qc0A:4 a=lN8H/RjlhkCyIsyuOn2r7w==:117 X-CM-Score: 0.00 Authentication-Results: cox.net; none From: "Al Gietzen" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Radiator cap - system pressure Date: Mon, 13 Sep 2010 06:19:21 -0800 Message-ID: <1D1862C4F04A4F7780E87C38F6EF78B1@BigAl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000B_01CB530B.9A90D600" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6863 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.5931 Importance: Normal Thread-Index: ActTMmuq0qnAUSa7S2mQ/vNGIymnOwAGo/8g In-Reply-To: This is a multi-part message in MIME format. ------=_NextPart_000_000B_01CB530B.9A90D600 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Chris; =20 More pressure doesn't translate to more cooling, but it does increase = the temp at which it will boil, and reduce the probability of cavitation in = the pump. And recognizing that pressure caps are differential pressure = valves (the absolute pressure on the coolant decreases with altitude), it's = good to use a cap with a relatively high pressure, maybe about 25 psi. I'd also suggest that the plumbing should be such that the pressure cap is on the inlet side of the water pump. =20 Probably the first thing affected by higher pressure would be coolant = system hoses. If you use good quality hoses, and change them every few years or = 100 hours, pressures up to 30 psi should not be an issue. =20 Al =20 -----Original Message----- From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Chris and Terria Sent: Monday, September 13, 2010 2:56 AM To: Rotary motors in aircraft Subject: [FlyRotary] Radiator cap - system pressure =20 Gents, =20 What pressure caps are you running with? What maximum should be used? = I currently have a 16 lb cap, but have found ones up to 29 - 31 lbs. I = know more pressure means more cooling, but is there a maximum limit before hurting the engine? =20 Chris ------=_NextPart_000_000B_01CB530B.9A90D600 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Chris;

 

More pressure doesn’t = translate to more cooling, but it does increase the temp at which it will boil, and = reduce the probability of cavitation in the pump.  And recognizing that = pressure caps are differential pressure valves (the absolute pressure on the = coolant decreases with altitude), it’s good to use a cap with a relatively = high pressure, maybe about 25 psi. I’d also suggest that the plumbing = should be such that the pressure cap is on the inlet side of the water = pump.

 

Probably the first thing affected = by higher pressure would be coolant system hoses. If you use good quality hoses, = and change them every few years or 100 hours, pressures up to 30 psi should = not be an issue.

 

Al

 

-----Original = Message-----
From: Rotary motors in = aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Chris and Terria
Sent: Monday, September = 13, 2010 2:56 AM
To: Rotary motors in = aircraft
Subject: [FlyRotary] = Radiator cap - system pressure

 

Gents,

 

What pressure caps are you running = with?  What maximum should be used?  I currently have a 16 lb cap, but have = found ones up to 29 – 31 lbs.  I know more pressure means more cooling, = but is there a maximum limit before hurting the engine?

 

Chris

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