Return-Path: Sender: "Marvin Kaye" To: lml@lancaironline.net Date: Wed, 22 Dec 2004 16:23:53 -0500 Message-ID: X-Original-Return-Path: Received: from systems3.net ([68.14.236.16] verified) by logan.com (CommuniGate Pro SMTP 4.2.5) with ESMTP-TLS id 577159 for lml@lancaironline.net; Wed, 22 Dec 2004 15:35:26 -0500 Received-SPF: none receiver=logan.com; client-ip=68.14.236.16; envelope-from=cberland@systems3.net Received: from systems0d3b724 ([192.168.1.81]) by systems3.net (8.13.1/8.13.1/Debian-12) with SMTP id iBMKYulP030391 for ; Wed, 22 Dec 2004 13:34:56 -0700 X-Original-Message-ID: <009301c4e865$1aee1cd0$5101a8c0@systems0d3b724> From: "Craig Berland" X-Original-To: "Lancair Mail List" Subject: Re: Electrical ignitio X-Original-Date: Wed, 22 Dec 2004 13:30:36 -0700 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_008E_01C4E82A.6B7C8690" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1437 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1441 X-Virus-Scanned: clamd / ClamAV version 0.75-1, clamav-milter version 0.75c on linux X-Virus-Status: Clean This is a multi-part message in MIME format. ------=_NextPart_000_008E_01C4E82A.6B7C8690 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable 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 ******************* ******************* George, you are right .385/.395 BSFC is VERY good and numbers the auto = industry does not match. A low friction 4 valve per cylinder auto = engine will do well getting a .43 BSFC at LBT (lean best torque). I = never tested lean of best torque. Obviously, BSFC goes up as you close = the throttle due to pumping losses. However.....it does matter where the spark comes from. If the mag or = other device does not have enough spark energy to create a "Quality = flame kernel" then the burn duration will increase and the brake torque = will decrease. If it misfires, I believe we all can picture that = problem. Spark plug life can also be a function of available spark = energy. Having multiple coils may not be as important on aircraft = engines (6 cylinders running 2700 RPM) as it is on auto engines (8 = cylinders running at 6000 RPM) since the time to saturate the coil is = much longer for an aircraft engine. But keep in mind turbocharged and = high compression ratio engines require more spark energy to fire the = plugs. The other huge benefit to electronic ignition is....the engine = can crank with the ignition firing at TDC, greatly making life easier on = the starter. In defense of magnetos, I have run an 8 cylinder engine = with 14 to 1 compression ration to 10,000 RPM on a single mag. However, = a battery ignition made more power. Electronic battery ignition is the = best concept however, I think the question has to be........Do you = believe in the quality of the hardware???? Not what system has the = highest potential. I personally do not have any durability experience = with any of the aircraft electronic ignitions. Additionally, if you are = running a 7.5 to 1 C.R. non turbo 4 cylinder engine, then mags are = probably just fine. Craig Berland IV-P ------=_NextPart_000_008E_01C4E82A.6B7C8690 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
I'm sure there=20 is someone
out there that has accurate data - and you know who you=20 are!

Gary Casey
IO-540, 2 mags, but one might get exchanged = for=20 something else.

You rang ???

Regards, =20 George

     ************************
OK... = seriously,  the problem with answering that question - - which = we =20 could do - -  is that it leads to a lot of wrong assumptions about = what is=20 "good".  Other technologies would lead a lot of people to do some = very=20 wrong things with their ignition systems. 
Properly = timed,  =20 an IO-540 operating at WOT at high power (25 to 28"MP) can have a BFSC = down=20 around 0.39 to 395.  (with 8.7:1 pistons).  At lower MP = (20") =20 the BSFC will not be as good.

A 520/550 class TCM engine will do = about=20 0385 under the same scenario.

These are very good numbers that = the=20 automotive world does not  achieve.

Regards, =20 George
 
*******************
*******************
George, you are=20 right .385/.395 BSFC is VERY good and numbers the auto industry does not = match.  A low friction 4 valve per cylinder auto engine will do = well=20 getting a .43 BSFC at LBT (lean best torque).  I never tested = lean of=20 best torque.  Obviously, BSFC goes up as you close the throttle due = to=20 pumping losses.
However.....it does matter where the spark comes = from.  If the=20 mag or other device does not have enough spark energy to create a = "Quality flame=20 kernel" then the burn duration will increase and the brake torque will=20 decrease.  If it misfires, I believe we all can picture that = problem. =20 Spark plug life can also be a function of available spark energy.  = Having=20 multiple coils may not be as important on aircraft engines (6 cylinders = running=20 2700 RPM) as it is on auto engines (8 cylinders running at 6000 RPM) = since=20 the time to saturate the coil is much longer for an aircraft = engine. =20 But keep in mind turbocharged and high compression ratio engines require = more spark energy to fire the plugs.  The other huge benefit = to=20 electronic ignition is....the engine can crank with the ignition firing = at TDC,=20 greatly making life easier on the starter.  In defense of magnetos, = I have=20 run an 8 cylinder engine with 14 to 1 compression ration to 10,000 RPM = on a=20 single mag.  However, a battery ignition made more power.  = Electronic=20 battery ignition is the best concept however, I think the question has = to=20 be........Do you believe in the quality of the hardware????  Not = what=20 system has the highest potential.  I personally do not have any = durability=20 experience with any of the aircraft electronic ignitions. Additionally, = if you=20 are running a 7.5 to 1 C.R. non turbo 4 cylinder engine, then mags are = probably=20 just fine.
 
Craig=20 Berland
IV-P


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