X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from qw-out-2122.google.com ([74.125.92.27] verified) by logan.com (CommuniGate Pro SMTP 5.2.16) with ESMTP id 3816758 for flyrotary@lancaironline.net; Tue, 18 Aug 2009 08:52:14 -0400 Received-SPF: pass receiver=logan.com; client-ip=74.125.92.27; envelope-from=rwstracy@gmail.com Received: by qw-out-2122.google.com with SMTP id 3so1112190qwe.25 for ; Tue, 18 Aug 2009 05:51:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:sender:received:in-reply-to :references:date:x-google-sender-auth:message-id:subject:from:to :content-type; bh=mJFlBSeg5nARwvC63bgPcr28NZH6GZZQvWAHhsDWMH4=; b=j3MKOFAA5VuaN13n2v55H8HXCTvbRTM98xLh5YBHRcA9oI0JGDNKhTWmsC/QFmdmOl olqLfP3R5PbiirWgEmllE0NcDGdkXU8fnkzn/Ae+Fd56WVkL595nD1XbNxrZb59q3vt4 i8WJOn/dZpWL0/TgeV7SDjuYOBdzz2YcJYTmk= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:content-type; b=dNyV0bRIfvhV/N6FKpbRKdy6VfVncXPl3UFqPIn3kazli7uy/l6KEzTgpaK55+Q2YW OyDl+km79ADKv+b4N8AUTsUUs+7CJ2b0Q9L9+SZjGnnLhMKIRvyaMnzFR87rNmHd043H EiUD1nX0aZn0u7PtS6S2fa7IP5vJmeXfo59zc= MIME-Version: 1.0 Sender: rwstracy@gmail.com Received: by 10.224.30.131 with SMTP id u3mr5344621qac.175.1250599901027; Tue, 18 Aug 2009 05:51:41 -0700 (PDT) In-Reply-To: References: Date: Tue, 18 Aug 2009 08:51:40 -0400 X-Google-Sender-Auth: d728f0cbd407a6af Message-ID: <1b4b137c0908180551q5378ef12of82ddb91374da754@mail.gmail.com> Subject: Re: [FlyRotary] Re: Swirl pots From: Tracy Crook To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=000feaeebdb5db77dd047169fa17 --000feaeebdb5db77dd047169fa17 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable I agree with Lynn (on the restriction) and Al on the swirl pot (not necessary). Note that there is a built in restriction in the Mazda water pump housing. Its just barely big enough to squeeze a couple of fingers through. A restriction does restrict the maximum flow but the pressure in the block (and back pressure on the pump) does 2 good things. Reduces the chance of bulk or film boiling in the block by raising boiling point and more importantly, the pressure reduces the likelihood of pump cavitation which would reduce flow much more than the restriction does and eliminate the pum= p damage that cavitation does. In other words, the engineers were willing to give up a little maximum flo= w in order to insure a higher minimum flow. This won't end the age old debate on this subject but that's my story and I'm stick'n to it : ) Tracy On Tue, Aug 18, 2009 at 2:00 AM, Al Gietzen wrote: > I respectfully disagree with the idea of the putting a flow restriction > at the exit of the engine. True, it does increase the coolant pressure i= n > the block, and that=92s good. But it reduces flow, and that=92s bad. Red= uced > flow increases the delta T around the loop and reduces the cooling capaci= ty > of the radiator, and in an aircraft application we don=92t like to add > additional radiator size. As far as increasing the pressure in the block= , > you can get about the same affect by plumbing the filler/pressure cap to > the inlet side of the pump rather than the outlet, so the pressure drop > around the loop is not seen by the cap. > > A swirl pot works, but is not necessary. You need an air bleed from the > high point of the engine (usually the outlet of the pump, and from other > places that the air may get trapped, like the rad tank. A small bleed li= ne > (3/16=94 o.d. aluminum is good) from the point the air gets trapped back = to > the filler neck/bottle. Since the filler neck is plumbed to the low > pressure side of the loop, any air gets drawn back there. > > I connected the turbo coolant port on the rear iron of my 20B back to the > port on the pump outlet to bleed air from the rear iron, and a manual ble= ed > plug at the pump outlet to vent air during fillup. I have small bleed li= nes > from each of two custom radiator tanks back to the filler neck (which is > connected to the line just before the pump inlet). After fillup, one run > cycle purges all the air back to the filler neck. > > BTW; the cold to hot expansion for my 20B system is about 2/3 of a quart. > > Works for me, but of course each installation is different; but the conce= pt > is the same. > > Al G > > > --000feaeebdb5db77dd047169fa17 Content-Type: text/html; charset=windows-1252 Content-Transfer-Encoding: quoted-printable I agree with Lynn (on the restriction) and Al on the swirl pot (not necessa= ry).

Note that there is a built in restriction in the Mazda water pu= mp housing.=A0 Its just barely big enough to squeeze a couple of fingers th= rough.=A0 A restriction does restrict the maximum flow but the pressure in = the block (and back pressure on the pump)=A0 does 2 good things.=A0 Reduces= the chance of bulk or film boiling in the block by raising boiling point a= nd more importantly, the pressure reduces the likelihood of pump cavitation= which would reduce flow much more than the restriction does and eliminate = the pump damage that cavitation does.
In other words,=A0 the engineers were willing to give up a little maximum f= low in order to insure a higher minimum flow.

This won't end the= age old debate on this subject but that's my story and I'm stick&#= 39;n to it : )


Tracy

On Tue, Aug 18, 2009 at 2:0= 0 AM, Al Gietzen <ALVentures@cox.net> wrote:

I respectfully disagree with t= he idea of the putting a flow restriction at the exit of the engine.=A0 True, it does increase the coolant pressure in the block, and that=92s good. But it reduces flow, and that=92s bad.=A0 Reduced flow increases the delta T around the loop and reduces the cooling capacity of the radiator, and in an aircraft application we don=92t like to add additional radiator size.=A0 As far as increasing the pressure in the block, you can get about the same affect by plumbing the filler/pressure cap to the inlet side of the pump rather than the outle= t, so the pressure drop around the loop is not seen by the cap.<= /p>

A swirl pot works, but is not necessary.=A0 You need an air bleed from the high point of the engine (usually the outlet of the pump, and from other places that the air may get trapped, like the rad tank.=A0 A small bleed line (3/16=94 o.d. aluminum is good) from the point the air gets trapped back to the filler neck/bottle= . =A0Since the filler neck is plumbed to the low pressure side of the loop, any air ge= ts drawn back there.

I connected the turbo coolant = port on the rear iron of my 20B back to the port on the pump outlet to bleed air fr= om the rear iron, and a manual bleed plug at the pump outlet to vent air durin= g fillup. =A0I have small bleed lines from each of two custom radiator tanks back to the filler neck (which is connected to the line just before the pum= p inlet).=A0 After fillup, one run cycle purges all the air back to the fille= r neck.

BTW; the cold to hot expansion= for my 20B system is about 2/3 of a quart.

Works for me, but of course ea= ch installation is different; but the concept is the same.

Al G

=A0


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