X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from imo-m14.mx.aol.com ([64.12.138.204] verified) by logan.com (CommuniGate Pro SMTP 5.1.12) with ESMTP id 2385777 for flyrotary@lancaironline.net; Sun, 14 Oct 2007 02:44:33 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.12.138.204; envelope-from=Lehanover@aol.com Received: from Lehanover@aol.com by imo-m14.mx.aol.com (mail_out_v38_r9.3.) id q.c41.1ea2bcbd (32913) for ; Sun, 14 Oct 2007 02:43:53 -0400 (EDT) From: Lehanover@aol.com Message-ID: Date: Sun, 14 Oct 2007 02:43:52 EDT Subject: Re: [FlyRotary] Re: FW: [FlyRotary] Re: Coolant Water Pressure To: flyrotary@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1192344232" X-Mailer: 9.0 Security Edition for Windows sub 5378 X-Spam-Flag: NO -------------------------------1192344232 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 10/13/2007 5:37:19 P.M. Eastern Daylight Time, lendich@optusnet.com.au writes: quite the surprise. Japanese engineers are expert at making sure the design has extra safety margin. Even back in the 70's. Although they are much better at it now. I can't imagine they are rpm sensitive 33 years later. I have heard of a lot of guys adding flow restrictions on pump inlet, not aware they are increasing pressure drop. Particularly true with fuel systems. -al wick Choking the inlet side of a centrifugal pump is a sure way to get into trouble. Same as out of tolerance suction lift. Notice that the exit hose from the radiator is larger than the inlet hose. My pump outlet has a 5/8" hole restrictor on the outlet. Same two water pumps for 9 years. Shifting at 9,600 RPM. No cavitation damage at all. Generally the radiator(s) will be enough restriction to keep the pump well below its top flow rate, and lowest inlet pressure. If there is little or no restriction on the outlet side, the pump might cavitate momentarily during acceleration. More likely with lower total system pressure, and low restriction. Less likely with an accumulator system and more restriction,and higher system pressure. Less likely with low system volume. More likely with high system volume. With just a bit of anti freeze and its anti foaming agents, very unlikely. More likely when air remains in the system. The pumps are mounted high on the block, and will not pump at all with a bit of air sitting in them. It is critical that the pump be submerged prior to start up. Lynn E. Hanover Lynn, Just to clarify! - Is that with standard pulley sizes? George ( down under) Stock pump size and pulley ratios are selected to allow day long idle in Death Valley with the air conditioning running. Radiator designed for maximum flow rates sufficient for day long full throttle runs across Death Valley with adequate cooling, without cavitation. I have never seen a pump damaged in any race car in 40 years. I bought a maroon Buick 4 door from a local pump company for $400.00, that had the sad GM 3.8 liter V-6 with very low oil pressure and the ends of the pump impeller blades chewed off, and a collapsed lower radiator hose. No spring reinforcement installed. Every time it came to idle the oil pressure idiot light came on. The tappets would bleed down and it would clatter like crazy. Then it would overheat. It was a salesmans car and had nearly 100,000 miles on it, but looked and smelled new. NAPA had a pump extension kit for the 3.8 and 4.2 V-6s for $25.00 that doubled the oil pump volume. A new lower hose and a rebuilt water pump, and I gave the mighty Buick to Good Will with 206,000 miles on it. It still looked and ran good. Unless a blockage develops between the radiator(s) and the engine, you will never see cavitation or pump damage at aviation RPM with nearly any drive ratios. Slowing the pump with smaller crank pulleys probably only endangers idle heat control. And not much even there. It might add one or two HP at cruise. Lynn E. Hanover ************************************** See what's new at http://www.aol.com -------------------------------1192344232 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable
In a message dated 10/13/2007 5:37:19 P.M. Eastern Daylight Time,=20 lendich@optusnet.com.au writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>
quite the surprise. Japanese engineers are expert at= making=20 sure the design has extra safety margin. Even back in the 70's. Although t= hey=20 are much better at it now. I can't imagine they are rpm sensitive 33 years= =20 later.
 
I have heard of a lot of guys adding=20= flow=20 restrictions on pump inlet, not aware they are increasing pressure dro= p.=20 Particularly true with fuel systems.
 
-al=20 wick
Choking the inlet side of a centrifugal pump is a sure way to g= et=20 into trouble. Same as out of tolerance suction lift. Notice that the exit ho= se=20 from the radiator is larger than the inlet hose.
 <= /DIV>
My pump outlet has a 5/8" hole restrictor on the outlet. Same two water= =20 pumps for 9 years. Shifting at 9,600 RPM. No cavitation damage at all. Gener= ally=20 the radiator(s) will be enough restriction to keep the pump well below its t= op=20 flow rate, and lowest inlet pressure. If there is little or no restriction o= n=20 the outlet side, the pump might cavitate momentarily during acceleratio= n.=20
 
More likely with lower total system pressure, and low restriction.=20= Less=20 likely with an accumulator system and more restriction,and higher system= =20 pressure. Less likely with low system volume. More likely with high= =20 system volume. With just a bit of anti freeze and its anti foaming agent= s,=20 very unlikely. More likely when air remains in the system. The pumps are= =20 mounted high on the block, and will not pump at all with a bit of air=20 sitting in them. It is critical that the pump be submerged prior to star= t=20 up.
 
Lynn E. Hanover

 
Lynn,
Just to clarify!  - Is that with standard pulley sizes?
George ( down under)
Stock pump size and pulley ratios are selected to allow day lon= g=20 idle in Death Valley with the air conditioning running. Radiator design= ed=20 for maximum flow rates sufficient for day long full throttle runs across Dea= th=20 Valley with adequate cooling, without cavitation. I have never seen a pump=20 damaged in any race car in
40 years. I bought a maroon Buick 4 door from a local pump comp= any=20 for $400.00, that had the sad GM 3.8 liter V-6 with very low oil pressure an= d=20 the ends of the pump impeller blades chewed off, and a collapsed lower=20 radiator hose. No spring reinforcement installed. Every time it came to idle= the=20 oil pressure idiot light came on. The tappets would bleed down and it would=20 clatter like crazy. Then it would overheat. It was a salesmans car and had=20 nearly 100,000 miles on it, but looked and smelled new. NAPA had a pump=20 extension kit for the 3.8 and 4.2 V-6s for $25.00 that doubled the oil pump=20 volume. A new lower hose and a rebuilt water pump, and I gave the mighty Bui= ck=20 to Good Will with 206,000 miles on it. It still looked and ran=20 good.
 
Unless a blockage develops between the radiator(s) and the engi= ne,=20 you will never see cavitation or pump damage at aviation RPM with nearly any= =20 drive ratios. Slowing the pump with smaller crank pulleys probably only=20 endangers idle heat control. And not much even there. It might add one or tw= o HP=20 at cruise.
 
Lynn E. Hanover 

 



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