X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from imr-ma02.mx.aol.com ([64.12.206.40] verified) by logan.com (CommuniGate Pro SMTP 5.3.9) with ESMTP id 4487931 for flyrotary@lancaironline.net; Thu, 30 Sep 2010 15:31:37 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.12.206.40; envelope-from=Bktrub@aol.com Received: from imo-ma03.mx.aol.com (imo-ma03.mx.aol.com [64.12.78.138]) by imr-ma02.mx.aol.com (8.14.1/8.14.1) with ESMTP id o8UJUpga026438 for ; Thu, 30 Sep 2010 15:30:51 -0400 Received: from Bktrub@aol.com by imo-ma03.mx.aol.com (mail_out_v42.9.) id q.f68.20e1d33 (43908) for ; Thu, 30 Sep 2010 15:30:49 -0400 (EDT) Received: from smtprly-md03.mx.aol.com (smtprly-md03.mx.aol.com [64.12.143.156]) by cia-dc07.mx.aol.com (v129.4) with ESMTP id MAILCIADC075-d4334ca4e560316; Thu, 30 Sep 2010 15:30:49 -0400 Received: from webmail-m097 (webmail-m097.sim.aol.com [64.12.101.43]) by smtprly-md03.mx.aol.com (v129.4) with ESMTP id MAILSMTPRLYMD032-d4334ca4e560316; Thu, 30 Sep 2010 15:30:40 -0400 References: To: flyrotary@lancaironline.net Subject: Re: [FlyRotary] Re: SAG from Paducah Date: Thu, 30 Sep 2010 15:30:39 -0400 X-AOL-IP: 208.46.237.130 In-Reply-To: X-MB-Message-Source: WebUI MIME-Version: 1.0 From: bktrub@aol.com X-MB-Message-Type: User Content-Type: multipart/alternative; boundary="--------MB_8CD2EED19857232_11C4_3884_webmail-m097.sysops.aol.com" X-Mailer: AOL Webmail 32679-STANDARD Received: from 208.46.237.130 by webmail-m097.sysops.aol.com (64.12.101.43) with HTTP (WebMailUI); Thu, 30 Sep 2010 15:30:39 -0400 Message-Id: <8CD2EED197BECAE-11C4-193C@webmail-m097.sysops.aol.com> X-Spam-Flag:NO X-AOL-SENDER: Bktrub@aol.com ----------MB_8CD2EED19857232_11C4_3884_webmail-m097.sysops.aol.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="us-ascii" So where can I get some of those high speed plugs and how much do they cos= t? Brian Trubee -----Original Message----- From: Lehanover@aol.com To: Rotary motors in aircraft Sent: Thu, Sep 30, 2010 9:42 am Subject: [FlyRotary] Re: SAG from Paducah In a message dated 9/30/2010 10:47:06 A.M. Eastern Daylight Time, SBoese@u= wyo.edu writes: Lynn and Bill, =20 Data recorded (including among others: RPM, EGT, coolant temperature, and= oil temperature) in flight under SAG conditions compared to data recorded= in flight under spark plug misfire conditions (by disabling ignition coil= s) suggest that the SAG event is possibly a preignition condition rather= than spark plug misfire due to fouling. =20 Examination of new and used spark plugs indicate that the preignition may= occur because of a gradual effective heat range change of the spark plug= with continued use as a result of decreasing thermal conductivity of the= copper core of the center electrode as well as corrosion between the cent= er electrode and the insulator at the insulator tip. The corrosion appear= s to be accelerated by the use of leaded fuel compared to the use of 87 oc= tane automotive fuel. =20 Steve Boese=20 Let us review............... =20 We take an engine from a car that usually operates below 2,200 RPM, and at= partial throttle for 99.5% of its life, and put it in airplane and run it= at 6,000 RPM and wide open throttle for hours on end, and even a cold str= eet plug is boiling cement and rounding electrodes? Now who could have gue= ssed that would happen. =20 The overheated plug boils the cement near the tip of the plug, thermally= disconnecting the electrode from the ceramic, and allowing the electrode= temperature to run away. This could lead to preignition (an ignition even= t that occurs before the planned ignition). Unless the mixture is well ric= h of ideal or well lean of ideal, the pre-ignition would lead quickly to= detonation followed by the apex seals getting stuck in the muffler.=20 =20 The high performance Mazda street plugs (turbo plugs) have shielding on th= e shell ends similar in appearance to some aircraft plugs. They are not ai= rcraft plugs. They will not survive hours at full load wide open throttle.= The heat range is cooler than most street plugs it is true, but nothing= like a racing plug.=20 =20 Real racing plugs do not have that shielding. They have a welded ground el= ectrode or a fine wire ground electrode stuck through the side of the shel= l. They have porcelain filling the shell all the way to the end and may ha= ve a fine wire center electrode. They are as cold a heat range as is possi= ble to produce. They are orders of magnitude colder than the coldest stree= t plug. =20 =20 More later. =20 Lynn E. Hanover ----------MB_8CD2EED19857232_11C4_3884_webmail-m097.sysops.aol.com Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset="us-ascii"
So where can I get some of those high speed plugs and how much do the= y cost?
 
Brian Trubee



-----Original Message-----
From: Lehanover@aol.com
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Thu, Sep 30, 2010 9:42 am
Subject: [FlyRotary] Re: SAG from Paducah

In a message dated 9/30/2010 10:47:06 A.M. Eastern Daylight Time, SBoese@uwyo.edu writes:
Lynn and Bill,
 
Data recorded (including among others:=  RPM, EGT, coolant temperature, and oil temperature) in flight= under SAG conditions compared to data recorded in flight under= spark plug misfire conditions (by disabling ignition coils) suggest that= the SAG event is possibly a preignition condition rather than= spark plug misfire due to fouling.
 
Examination of new and used spark plugs indicate= that the preignition may occur because of a gradual= effective heat range change of the spark plug with continued use as= a result of decreasing thermal conductivity of the copper core of the cen= ter electrode as well as corrosion between the center electrode and= the insulator at the insulator tip.  The corrosion appears= to be accelerated by the use of leaded fuel compared to the use= of 87 octane automotive fuel.
 
Steve Boese 
Let us review...............
 
We take an engine from a car that usually operates below 2,200 RPM,= and at partial throttle for 99.5% of its life, and put it in airplan= e and run it at 6,000 RPM and wide open throttle for hours on end, and eve= n a cold street plug is boiling cement and rounding electrodes? Now who co= uld have guessed that would happen.
 
The overheated plug boils the cement  near the tip of the plug,= thermally disconnecting the electrode from the ceramic, and allowing the= electrode temperature to run away. This could lead to preignition (an ign= ition event that occurs before the planned ignition). Unless the mixture= is well rich of ideal or well lean of ideal, the pre-ignition would lead= quickly to detonation followed by the apex seals getting stuck in the muf= fler.
 
The high performance Mazda street plugs (turbo plugs) have shielding= on the shell ends similar in appearance to some aircraft plugs. They are= not aircraft plugs. They will not survive hours at full load wide open th= rottle. The heat range is cooler than most street plugs it is true, but no= thing like a racing plug.
 
Real racing plugs do not have that shielding. They have a welded grou= nd electrode or a fine wire ground electrode stuck through the side= of the shell. They have porcelain filling the shell all the way to the en= d and may have a fine wire center electrode. They are as cold a heat range= as is possible to produce. They are orders of magnitude colder than the= coldest street plug.  
 
More later.
 
Lynn E. Hanover
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