X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 2 [X] Return-Path: Sender: To: lml@lancaironline.net Date: Fri, 30 Mar 2007 23:23:23 -0400 Message-ID: X-Original-Return-Path: Received: from imo-m21.mx.aol.com ([64.12.137.2] verified) by logan.com (CommuniGate Pro SMTP 5.1.7) with ESMTP id 1952913 for lml@lancaironline.net; Fri, 30 Mar 2007 18:24:04 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.12.137.2; envelope-from=REHBINC@aol.com Received: from REHBINC@aol.com by imo-m21.mx.aol.com (mail_out_v38_r7.10.) id q.ceb.ca88886 (41809) for ; Fri, 30 Mar 2007 18:23:10 -0400 (EDT) From: REHBINC@aol.com X-Original-Message-ID: X-Original-Date: Fri, 30 Mar 2007 18:23:10 EDT Subject: Re: [LML] Re: Thielert Diesel Centurion 4.0 X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1175293390" X-Mailer: 9.0 for Windows sub 5126 X-Spam-Flag: NO -------------------------------1175293390 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 3/30/2007 9:46:53 AM Eastern Standard Time, n103md@yahoo.com writes: Just as in a gas turbine, the cooling drag is minimized by allowing the hot section to actually run hot. High temperature, high strength alloys, and insulating ceramics are the key to an efficient aircraft diesel engine. FWIW, Aluminum is just about the worst material to use in a diesel head: low strength at high temperatures, high thermal conductivity, poor fatigue life, etc. The argument that "...heat has to be dissipated - - - some way." really boils down to "because we let the heat get into the aluminum, we need to get it back out before the piston melts." From a standpoint of power/efficiency, an aluminum head on an automotive gas engine works against you as well. As I recall from the days of big lizards, aluminum Bow Tie heads for a small block chevy gave up 10 hp compared to iron Bow Tie heads. In a race car, the reduction in weight for the aluminum heads more than offset the power loss. Also, you can get away with running a diesel a little hotter with or without coatings since you don't have to worry about preignition or detonation as you would on gas. Rob ************************************** See what's free at http://www.aol.com. -------------------------------1175293390 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable
In a message dated 3/30/2007 9:46:53 AM Eastern Standard Time, n103md@y= ahoo.com writes:
Just a= s in a gas turbine, the cooling drag is minimized by allowing the
hot se= ction to actually run hot. High temperature, high strength alloys,= and
insula= ting ceramics are the key to an efficient aircraft diesel engine.
FWIW,=20= Aluminum is just about the worst material to use in a diesel head:
low st= rength at high temperatures, high thermal conductivity, poor fatigue life, e= tc.
The ar= gument that "...heat  has to be dissipated - - - some way." really boil= s
down t= o "because we let the heat get into the aluminum, we need to get it
back o= ut before the piston melts."
From a standpoint of power/efficiency, an aluminum head on an automotiv= e gas engine works against you as well. As I recall from the days of bi= g lizards, aluminum Bow Tie heads for a small block chevy gave up 10 hp comp= ared to iron Bow Tie heads. In a race car, the reduction in weight for the a= luminum heads more than offset the power loss.
 
Also, you can get away with running a diesel a little hotter with or wi= thout coatings since you don't have to worry about preignition or detonation= as you would on gas.
 
Rob



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