X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from [65.54.250.91] (HELO hotmail.com) by logan.com (CommuniGate Pro SMTP 5.0.7) with ESMTP id 960211 for flyrotary@lancaironline.net; Sun, 29 Jan 2006 21:25:16 -0500 Received-SPF: pass receiver=logan.com; client-ip=65.54.250.91; envelope-from=lors01@msn.com Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; Sun, 29 Jan 2006 18:24:31 -0800 Message-ID: Received: from 4.171.129.19 by BAY115-DAV19.phx.gbl with DAV; Mon, 30 Jan 2006 02:24:31 +0000 X-Originating-IP: [4.171.129.19] X-Originating-Email: [lors01@msn.com] X-Sender: lors01@msn.com From: "Tracy Crook" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Renesis Cooling oddity Date: Sun, 29 Jan 2006 21:24:28 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_01DE_01C6251A.62A81D80" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: MSN 9 X-MimeOLE: Produced By MSN MimeOLE V9.10.0011.1703 Seal-Send-Time: Sun, 29 Jan 2006 21:24:28 -0500 X-OriginalArrivalTime: 30 Jan 2006 02:24:31.0627 (UTC) FILETIME=[4D9545B0:01C62544] This is a multi-part message in MIME format. ------=_NextPart_000_01DE_01C6251A.62A81D80 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable As Ed mentioned in a recent post, He gave me his spare radiator cap = when mine was found to be defective. It had been bad since day one when = I installed it on the Renesis installation. I had noticed that the = coolant pressure was low (almost zero) after the engine cooled down = after initial climb out but had written it off as normal for the new = system since it was cooling adequately. I've been flying with good pressure after replacing the cap and noticed = that the cooling system performance was generally better. What really = interested me was the change in temp differential between the water temp = at the combustion chamber side and the intake/exhaust port side (I = measure it in both locations). Previously, there was an 8 - 10 degree = rise in coolant temp as it went through the port side and I had assumed = this was due to the increased exhaust port heat transfer to the coolant = on the Renesis. This really bugged me since it represents a LOT of BTU = into the coolant. Now that the coolant pressure is normal (~10 psi at = cruise) the port side temp increase is down to 1 - 3 degrees. The = question is, why? So far, the leading theory is water pump cavitation. The low coolant = pressure allowed the pump to cavitate which reduces coolant flow rate = which in turn caused the temp rise to be higher. As a side note, the = Renesis uses the same pump design as the 3rd gen, a cheap stamped sheet = metal impeller instead of the nicely scrolled cast impeller of the 2nd = gen. I think the stamped impeller is more likely to cavitate. =20 Anyway, this almost eliminates what I considered to be the only down = side to the Renesis vs the earlier 13B. Tracy ------=_NextPart_000_01DE_01C6251A.62A81D80 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
As Ed mentioned in a recent post,  = He gave me=20 his spare radiator cap when mine was found to be defective.  It had = been bad since day one when I installed it on the Renesis=20 installation.  I had noticed that the coolant pressure was low = (almost=20 zero) after the engine cooled down after initial climb out but had = written it=20 off as normal for the new system since it was cooling=20 adequately.
 
I've been flying with good pressure after = replacing the=20 cap and  noticed that the cooling system performance was generally=20 better.  What really interested me was the change in temp = differential=20 between the water temp at the combustion chamber side and the = intake/exhaust=20 port side (I measure it in both locations).  Previously, there = was an 8 - 10 degree rise in coolant temp as it went through the = port side=20 and I had assumed this was due to the increased exhaust port heat = transfer to=20 the coolant on the Renesis.  This really bugged me since it = represents a=20 LOT of BTU into the coolant.  Now that the coolant pressure is = normal (~10=20 psi at cruise) the port side temp increase is down to 1 - 3 = degrees.  The=20 question is, why?
 
So far, the leading theory is water pump = cavitation. =20 The low coolant pressure allowed the pump to cavitate which reduces = coolant flow=20 rate which in turn caused the temp rise to be higher.  As a = side note,=20 the Renesis uses the same pump design as the 3rd gen, a cheap stamped = sheet=20 metal impeller instead of the nicely scrolled cast impeller of the 2nd=20 gen.  I think the stamped impeller is more likely to = cavitate. =20
 
Anyway, this almost eliminates what I considered = to be the=20 only down side to the Renesis vs the earlier 13B.
 
Tracy
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