X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from [24.25.9.102] (HELO ms-smtp-03-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 5.0.7) with ESMTP id 960290 for flyrotary@lancaironline.net; Sun, 29 Jan 2006 23:56:55 -0500 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.102; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-024-074-025-165.carolina.res.rr.com [24.74.25.165]) by ms-smtp-03-eri0.southeast.rr.com (8.13.4/8.13.4) with SMTP id k0U4u8Wa007632 for ; Sun, 29 Jan 2006 23:56:10 -0500 (EST) Message-ID: <003101c62559$7c51cad0$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Renesis Cooling oddity Date: Sun, 29 Jan 2006 23:56:09 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_002E_01C6252F.9338ED70" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_002E_01C6252F.9338ED70 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Here's another possibility to throw on the fire, Tracy. When I was doing some cooling test (several years ago), it was clear = that the coolant in the block was NOT like a pot of water waiting to = boil. In fact, it was more like a fire hose being used to force water = through the coolant galleys. I noticed that when I ran the engine with = the radiator cap off, the temperature sensors I had (used the stock rear = housing one as well as one at the pump outlet) indicated that the = coolant had air pockets in (might related to caviation as well), the = coolant temperature would jump and surge. When I placed the radiator = cap on the system the coolant temperature would stabilize and no = variations could be detected. I suspect that by putting a radiator cap on and pressurizing to 10 psi = that your coolant system perhaps no longer has air bubbles in the = coolant stream (certainly makes it a bit more difficult to form them = with 10 psi to fight) . If that were the case then, it might would = result inbetter heat transfer and equalization of heat on bothsides of = your exhaust port. Just a thought. Ed Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com ----- Original Message -----=20 From: Tracy Crook=20 To: Rotary motors in aircraft=20 Sent: Sunday, January 29, 2006 9:24 PM Subject: [FlyRotary] Re: Renesis Cooling oddity 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_002E_01C6252F.9338ED70 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Here's another possibility to throw on = the fire,=20 Tracy.
 
When I was doing some cooling test = (several years=20 ago), it was clear that the coolant in the block was NOT like a pot of = water=20 waiting to boil.  In fact, it was more like a fire hose being used = to force=20 water through the coolant galleys.  I noticed that when I ran the = engine=20 with the radiator cap off, the temperature sensors I had (used the stock = rear=20 housing one as well as one at the pump outlet) indicated that the = coolant had=20 air pockets in (might related to caviation as well), the coolant = temperature=20 would jump and surge.  When I placed the radiator cap on the system = the=20 coolant temperature would stabilize and no variations could be=20 detected.
 
I suspect that by putting a radiator = cap on and=20 pressurizing to 10 psi that your coolant system perhaps no longer has = air=20 bubbles in the coolant stream (certainly makes it a bit more difficult = to form=20 them with 10 psi to fight) .  If that were the case then, it might = would=20 result inbetter heat transfer and equalization of heat on bothsides of = your=20 exhaust port.  Just a thought.
 
Ed
 
Ed Anderson
Rv-6A N494BW Rotary=20 Powered
Matthews, NC
eanderson@carolina.rr.com
----- Original Message -----
From:=20 Tracy = Crook
Sent: Sunday, January 29, 2006 = 9:24=20 PM
Subject: [FlyRotary] Re: = Renesis Cooling=20 oddity

As Ed mentioned in a recent = post,  He gave=20 me his spare radiator cap when mine was found to be defective.  = It had=20 been bad since day one when I installed it on the Renesis=20 installation.  I had noticed that the coolant pressure was = low=20 (almost zero) after the engine cooled down after initial climb out but = had=20 written it 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=20 was an 8 - 10 degree rise in coolant temp as it went through the = port=20 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=20 represents a LOT of BTU into the coolant.  Now that the coolant = pressure=20 is normal (~10 psi at cruise) the port side temp increase is down to 1 = - 3=20 degrees.  The question is, why?
 
So far, the leading theory is water pump=20 cavitation.  The low coolant pressure allowed the pump to = cavitate which=20 reduces coolant flow rate which in turn caused the temp rise to = be=20 higher.  As a side note, the Renesis uses the same pump design as = the 3rd=20 gen, a cheap stamped sheet metal impeller instead of the nicely = scrolled cast=20 impeller of the 2nd gen.  I think the stamped impeller is more = likely to=20 cavitate. 
 
Anyway, this almost eliminates what I = considered to be=20 the only down side to the Renesis vs the earlier 13B.
 
Tracy
------=_NextPart_000_002E_01C6252F.9338ED70--