Return-Path: Received: from [65.33.167.114] (account marv@lancaironline.net) by logan.com (CommuniGate Pro WebUser 4.2b1) with HTTP id 3131933 for lml@lancaironline.net; Sun, 28 Mar 2004 17:50:40 -0500 From: "Marvin Kaye" Subject: Re: [LML] Re: relative temps? To: lml X-Mailer: CommuniGate Pro WebUser Interface v.4.2b1 Date: Sun, 28 Mar 2004 17:50:40 -0500 Message-ID: In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format="flowed" Content-Transfer-Encoding: 8bit Posted for "George Braly" : Interesting. I suspect the reason you did not see improvement in performance after the 9:1 pistons on the LASAR was because it was timing much to early, and that was corrected during the subsequent magneto replacement/shuffle. At high power ... changing the spark timing over a range of plus/minus 3 or 4 degrees off of Max Brake Torque (MBT) timing has remarkably SMALL effects on Hp. Almost unnoticeable to a pilot. Like maybe a range from 160 Hp to 155 or 157 Hp on a 320 sized engine. This concept is almost universally mis-understood by engine builders. For example, most IO-520 and 550 TCM engines are OVER timed at full power and would actually make a bit more Hp if the timing was retarded slightly. At lower power settings, the engines are a bit more sensitive to optimal timing to achieve MBT, as compared to full power operation. What do your EGTs run at full power on take off ? At what fuel flow? Regards, George _____ > > > I had a 400 hour Don George 1992 Cermichromed I/O 320 with 9:1 pistons and a Hartzell carved (thickness tapers at the end), 70 inch constant speed prop. I replaced BOTH Slick mags with the LASAR system (O 320 Control Unit (CU)), all timed for 25* BTDC. I immediately experienced energetic takeoff runs, better climb rates and better performance ROP at altitude. The EGTs were about 70 degrees cooler than similar power settings achieved with the old mags - The CHTs were 15 to 20 degrees higher. I have not retained data from that era. ...snip...