X-Virus-Scanned: clean according to Sophos on Logan.com X-PolluStop: No license found, only first 5 messages were scanned Return-Path: Sender: To: lml Date: Tue, 27 Jun 2006 16:09:32 -0400 Message-ID: X-Original-Return-Path: Received: from imo-d21.mx.aol.com ([205.188.144.207] verified) by logan.com (CommuniGate Pro SMTP 5.1c.1) with ESMTP id 1208405 for lml@lancaironline.net; Tue, 27 Jun 2006 12:23:27 -0400 Received-SPF: pass receiver=logan.com; client-ip=205.188.144.207; envelope-from=REHBINC@aol.com Received: from REHBINC@aol.com by imo-d21.mx.aol.com (mail_out_v38_r7.5.) id q.251.cd169b8 (48624) for ; Tue, 27 Jun 2006 12:22:25 -0400 (EDT) From: REHBINC@aol.com X-Original-Message-ID: <251.cd169b8.31d2b541@aol.com> X-Original-Date: Tue, 27 Jun 2006 12:22:25 EDT Subject: Re: [LML] Re: Straight bore vs choke X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1151425345" X-Mailer: 9.0 Security Edition for Windows sub 5318 X-Spam-Flag: NO -------------------------------1151425345 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 6/26/2006 6:04:56 P.M. Eastern Standard Time, walter@advancedpilot.com writes: If one runs the mixture properly to keep the peak ICP out of the choke area, having choke in the barrel is a good thing. If one operates the mixture in such a manner so as to place the thetaPP too close to TDC, then not having choke could be a way to overcome the error slightly. Having no choke is one way of covering up poor technique. It is a sub-optimal way to do things IMO. Walter Interesting conclusions Walter. Seems to me that operating with theta PP closer to TDC would increase the need for choke. Essentially, the fluid temperature varies directly with the pressure and the heat transfer rate per unit area varies directly with the temperature. Thus, moving theta PP closer to TDC would result in additional heat transfer to the upper combustion chamber and less heat transfer to the lower chamber. This results in increased differential thermal expansion of the barrel and a flaring effect at the top of the cylinder. I could be mistaken, but I am of the understanding that countering this flaring effect is the whole point of cylinder choke. As for the claim of an unchoked barrel being better, if the cooling fins were better optimized to the operating heat transfer rates, then the cylinder would remain straight at operating temperature without the need for choke. Also, when a choked barrel is started from cold, it generates additional ring movement until it reaches its design temperature. This results in additional wear to the ring lands. I have no knowledge whether Chuck Ney has altered the cooling fins, found through experience that choke is unnecessary or if he is simply B.S. promoting a cheaper manufacturing process. Rob -------------------------------1151425345 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable

In a message dated 6/26/2006 6:04:56 P.M. Eastern Standard Time,=20 walter@advancedpilot.com writes:

<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>If one=20 runs the mixture properly to keep the peak ICP out of the choke
area,=20 having choke in the barrel is a good thing. If one operates the=20
mixture in such a manner so as to place the thetaPP too close to TDC,=20
then not having choke could be a way to overcome the error slightly.&n= bsp;=20
Having no choke is one way of covering up poor technique. It is=20= a=20
sub-optimal way to do things=20 IMO.

Walter

Interesting conclusions Walter.

Seems to me that operating with theta PP closer to TDC would increase t= he=20 need for choke.

Essentially, the fluid temperature varies directly with the pressure an= d=20 the heat transfer rate per unit area varies directly with the temperature. T= hus,=20 moving theta PP closer to TDC would result in additional heat transfer to th= e=20 upper combustion chamber and less heat transfer to the lower chamber. This=20 results in increased differential thermal expansion of the barrel = and=20 a flaring effect at the top of the cylinder.

I could be mistaken, but I am of the understanding that countering this= =20 flaring effect is the whole point of cylinder choke.

As for the claim of an unchoked barrel being better, if the cooling fin= s=20 were better optimized to the operating heat transfer rates, then the cylinde= r=20 would remain straight at operating temperature without the need for choke. A= lso,=20 when a choked barrel is started from cold, it generates additional ring move= ment=20 until it reaches its design temperature. This results in additional wear to=20= the=20 ring lands. I have no knowledge whether Chuck Ney has altered the cooli= ng=20 fins, found through experience that choke is unnecessary or if he is simply=20= B.S.=20 promoting a cheaper manufacturing process.

Rob

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