Return-Path: Sender: "Marvin Kaye" To: lml@lancaironline.net Date: Wed, 22 Dec 2004 12:26:16 -0500 Message-ID: X-Original-Return-Path: Received: from [68.89.254.181] (HELO sdf1.mail.taturbo.com) by logan.com (CommuniGate Pro SMTP 4.2.5) with ESMTP id 576667 for lml@lancaironline.net; Wed, 22 Dec 2004 09:48:38 -0500 Received-SPF: none receiver=logan.com; client-ip=68.89.254.181; envelope-from=gwbraly@gami.com MIME-Version: 1.0 Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable Subject: RE: [LML] Re: Electrical ignition X-MimeOLE: Produced By Microsoft Exchange V6.0.6487.1 content-class: urn:content-classes:message X-Original-Date: Wed, 22 Dec 2004 08:54:45 -0600 X-Original-Message-ID: X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: [LML] Re: Electrical ignition Thread-Index: AcTn39ia2LtVX/BIQMWGRQV0nscq9wAVcqtA From: "George Braly" X-Original-To: "Lancair Mailing List" Gary, Here's my question: With these engines the numbers should be very consistent. What compression ratio to assume - not sure, but pick one. Given a manifold absolute pressure of, say, 20 inches, a fixed rpm of = 2400 to 2500 and a fixed mixture of maybe 30 LOP, what is the optimum (MBT) ignition timing with both ignitions at the same timing setting? What is = the optimum timing for the second ignition if one ignition is set at 20 BTC? What is the BSFC in each of the three conditions? I'm sure there is = someone out there that has accurate data - and you know who you are! Gary Casey IO-540, 2 mags, but one might get exchanged for something else. You rang ??? Regards, George ************************ OK... seriously, the problem with answering that question - - which we = could do - - is that it leads to a lot of wrong assumptions about what = is "good". Other technologies would lead a lot of people to do some = very wrong things with their ignition systems. =20 Properly timed, an IO-540 operating at WOT at high power (25 to 28"MP) = can have a BFSC down around 0.39 to 395. (with 8.7:1 pistons). At = lower MP (20") the BSFC will not be as good. A 520/550 class TCM engine will do about 0385 under the same scenario. These are very good numbers that the automotive world does not achieve. Regards, George --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.818 / Virus Database: 556 - Release Date: 12/17/2004 =20