Return-Path: Sender: (Marvin Kaye) To: flyrotary Date: Thu, 03 Oct 2002 00:03:39 -0400 Message-ID: X-Original-Return-Path: Received: from cpimssmtpu10.email.msn.com ([207.46.181.85] verified) by logan.com (CommuniGate Pro SMTP 4.0b8) with ESMTP id 1796616 for flyrotary@lancaironline.net; Thu, 03 Oct 2002 00:02:46 -0400 Received: from bhickman ([65.142.114.194]) by cpimssmtpu10.email.msn.com with Microsoft SMTPSVC(5.0.2195.4905); Wed, 2 Oct 2002 21:01:35 -0700 X-Original-Message-ID: <004101c26a92$d2acbaa0$284ffea9@suwanneevalley.net> Reply-To: "Tracy Crook" From: "Tracy Crook" X-Original-To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: water pumps X-Original-Date: Thu, 3 Oct 2002 00:10:32 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-Original-Return-Path: lors01@msn.com X-OriginalArrivalTime: 03 Oct 2002 04:01:36.0253 (UTC) FILETIME=[916E6AD0:01C26A91] > That makes sense. But I got to wondering as to exactly what conditions the pump > _and pulley!_ were designed around. What if, at 5000 or more rpm at cruise, we > have more capacity than we need, and end up pumping a lot of back pressure > against a partially closed thermostat. A scenario like that would be wasted > power. If that were so, and we just put a larger pulley on the pump, it would > not absorb as much power, and the lower pump rpm would better match > requirements. How do we tell if a water pump/pulley configuration is wasting > power trying to over achieve? Has anyone tried a larger pulley (less pump speed, > less power drain, less flow, but still plenty sufficient for the application)?? > Tracy, are you out there?? > Inquiring minds need to know .... Jim S. > I use an underdrive pulley (smaller than stock) on the crankshaft which slows the pump down. The real reason I use it is to slow down the alternator. Cooling is still good but I noticed a *very slight* decrease in cooling system performance when I went to the smaller pulley. This is only noticable in climb on a hot day. In general, I think the pump speed & performance with the stock pulley is well matched to engine requirements and this is what I will use on my 20B. Tracy Crook tcrook@rotaryaviation.com www.rotaryaviation.com