Return-Path: Received: from wb1-a.mail.utexas.edu ([128.83.126.134] verified) by logan.com (CommuniGate Pro SMTP 4.2.5) with ESMTP-TLS id 524285 for flyrotary@lancaironline.net; Tue, 09 Nov 2004 09:34:54 -0500 Received-SPF: none receiver=logan.com; client-ip=128.83.126.134; envelope-from=msteitle@mail.utexas.edu Received: (qmail 22394 invoked from network); 9 Nov 2004 14:34:22 -0000 Received: from dhcp-191-101.per.utexas.edu (HELO hrs-mark.mail.utexas.edu) (146.6.191.101) by wb1.mail.utexas.edu with SMTP; 9 Nov 2004 14:34:22 -0000 Message-Id: <5.1.1.5.2.20041109082702.022bd250@localhost> X-Sender: msteitle@mail.utexas.edu@localhost X-Mailer: QUALCOMM Windows Eudora Version 5.1.1 Date: Tue, 09 Nov 2004 08:34:15 -0600 To: "Rotary motors in aircraft" From: Mark Steitle Subject: Re: [FlyRotary] Re: EWP In-Reply-To: Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="=====================_57835140==.ALT" --=====================_57835140==.ALT Content-Type: text/plain; charset="us-ascii"; format=flowed Al, Good data, but for clarification, aren't you running a 13B pump on your 20B? Are you running stock main pulley or an undersized pulley? The 20B pump should flow more gpm due to a slightly larger impeller. Also, comparing a 20B eccentric pulley with a 13B from an 89 n/a engine, the 20B pulley is larger, which should also increase flow, up to the point of cavitation. Mark S. >I don t disagree with your flow assessment for the car; but consider >this. My engineering analysis (all the same stuff that our friend Bill >Shertz has now plotted out for everyone) for designing a somewhat optimum >cooling system for my 20B told me I needed 40 to 50 gpm flow rate at 6000 >rpm and 260 hp; that range depending on variable factors. For a 13B that >something like 22 to 33 gpm. When I measured the flow rate during the >dyno tests I was pleased to find that the pump produced 48 gpm, with no >thermostat, and 37 gpm with a thermostat. This was pumping thru the >engine and through the dyno loop which I know has less back pressure than >my plane s cooling loop, so my actual flow will be less. > > > >So I don t see any excess flow over what I need at high rpm/power, even >running the engine without a thermostat. Yes, there are regimes where it >will be pumping more than I need in the same regimes where I don t care >whether I m wasting 1 hp driving a bit more flow than needed. And, I >could also put in bigger (heavier) radiators and run a larger delta T and >a bit less flow. > > > >(OK, I lied, get on with the beheading it s only because I m not feeling >well and sitting around at my computer instead of working on the airplane; >honest) > > > >Al --=====================_57835140==.ALT Content-Type: text/html; charset="us-ascii" Al,
Good data, but for clarification, aren't you running a 13B pump on your 20B? Are you running stock main pulley or an undersized pulley? The 20B pump should flow more gpm due to a slightly larger impeller. Also, comparing a 20B eccentric pulley with a 13B from an 89 n/a engine, the 20B pulley is larger, which should also increase flow, up to the point of cavitation.

Mark S.

I don t disagree with your flow assessment for the car; but consider this. My engineering analysis (all the same stuff that our friend Bill Shertz has now plotted out for everyone) for designing a somewhat optimum cooling system for my 20B told me I needed 40 to 50 gpm flow rate at 6000 rpm and 260 hp; that range depending on variable factors. For a 13B that something like 22 to 33 gpm. When I measured the flow rate during the dyno tests I was pleased to find that the pump produced 48 gpm, with no thermostat, and 37 gpm with a thermostat. This was pumping thru the engine and through the dyno loop which I know has less back pressure than my plane s cooling loop, so my actual flow will be less.

So I don t see any excess flow over what I need at high rpm/power, even running the engine without a thermostat. Yes, there are regimes where it will be pumping more than I need in the same regimes where I don t care whether I m wasting 1 hp driving a bit more flow than needed. And, I could also put in bigger (heavier) radiators and run a larger delta T and a bit less flow.

(OK, I lied, get on with the beheading it s only because I m not feeling well and sitting around at my computer instead of working on the airplane; honest)

Al

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