Received-SPF: pass
 receiver=logan.com; client-ip=64.12.206.42; envelope-from=Lehanover@aol.com
From: Lehanover@aol.com
Message-ID: <34b63.6a3a429b.39d61804@aol.com>
Date: Thu, 30 Sep 2010 12:42:44 EDT
Subject: Re: [FlyRotary] Re: SAG from Paducah
To: flyrotary@lancaironline.net
MIME-Version: 1.0
Content-Type: multipart/alternative; boundary="part1_34b63.6a3a429b.39d61804_boundary"


--part1_34b63.6a3a429b.39d61804_boundary
Content-Type: text/plain; charset="US-ASCII"
Content-Transfer-Encoding: 7bit

 
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 center 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 airplane and run it  
at 6,000 RPM and wide open throttle for hours on end, and even a cold street 
 plug is boiling cement and rounding electrodes? Now who could 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 ignition  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 muffler. 
 
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 throttle. 
The heat  range is cooler than most street plugs it is true, but nothing like 
a racing  plug. 
 
Real racing plugs do not have that shielding. They have a welded ground  
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 end 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

--part1_34b63.6a3a429b.39d61804_boundary
Content-Type: text/html; charset="US-ASCII"
Content-Transfer-Encoding: quoted-printable

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META content=3D"text/html; charset=3DUS-ASCII" http-equiv=3DContent-Type>
<META name=3DGENERATOR content=3D"MSHTML 8.00.6001.18939"></HEAD>
<BODY style=3D"FONT-FAMILY: Arial; COLOR: #000000; FONT-SIZE: 10pt" id=3Dr=
ole_body  bottomMargin=3D7 leftMargin=3D7 rightMargin=3D7 topMargin=3D7><F=
ONT id=3Drole_document  color=3D#000000 size=3D2 face=3DArial>
<DIV>
<DIV>In a message dated 9/30/2010 10:47:06 A.M. Eastern Daylight Time,=20
SBoese@uwyo.edu writes:</DIV>
<BLOCKQUOTE  style=3D"BORDER-LEFT: blue 2px solid; PADDING-LEFT: 5px; MARG=
IN-LEFT: 5px"><FONT    style=3D"BACKGROUND-COLOR: transparent" color=3D#00=
0000 size=3D2 face=3DArial>
  <DIV>Lynn and Bill,</DIV>
  <DIV><FONT face=3Darial></FONT>&nbsp;</DIV>
  <DIV><FONT face=3Darial>Data recorded (including&nbsp;among<A></A>=20
  others:&nbsp;RPM, EGT<A></A>, coolant temperature, and oil temperature)=
 in=20
  flight under SAG conditions&nbsp;compared to data recorded&nbsp;in fligh=
t=20
  under spark plug misfire conditions (by disabling ignition coils) sugges=
t that=20
  the SAG event is possibly a&nbsp;preignition<A></A> condition rather tha=
n=20
  spark plug misfire due to fouling.</FONT></DIV>
  <DIV>&nbsp;</DIV>
  <DIV><FONT face=3Darial>Examination of new and used spark plugs indicate=
 that=20
  the&nbsp;preignition<A></A> may occur&nbsp;because of a&nbsp;gradual eff=
ective=20
  heat range change of the spark plug&nbsp;with continued use as a result=
 of=20
  decreasing thermal conductivity of the copper core of the center electro=
de as=20
  well as corrosion between the center&nbsp;electrode and the insulator at=
=20
  the&nbsp;insulator tip.&nbsp; The corrosion&nbsp;appears to=20
  be&nbsp;accelerated by the use of&nbsp;leaded fuel compared to the use=
=20
  of&nbsp;87 octane automotive fuel.</FONT></DIV>
  <DIV>&nbsp;</DIV>
  <DIV><FONT  face=3Darial>Steve&nbsp;Boese<A></A></FONT>&nbsp;</DIV></FON=
T></BLOCKQUOTE></DIV>
<DIV></DIV>
<DIV>Let us review...............</DIV>
<DIV>&nbsp;</DIV>
<DIV>We take an engine from a car that usually operates below 2,200 RPM,=
 and at=20
partial throttle&nbsp;for 99.5% of its life, and put it in airplane and ru=
n it=20
at 6,000 RPM and wide open throttle for hours on end, and even a cold stre=
et=20
plug is boiling cement and rounding electrodes? Now who could have guessed=
 that=20
would happen.</DIV>
<DIV>&nbsp;</DIV>
<DIV>The overheated plug boils the cement&nbsp; near the tip of the plug,=
=20
thermally disconnecting the electrode from the ceramic, and allowing the=
=20
electrode temperature to run away. This could lead to preignition (an igni=
tion=20
event that occurs before the planned ignition). Unless the mixture is well=
 rich=20
of ideal or well lean of ideal, the pre-ignition would lead quickly to=20
detonation followed by the apex seals getting stuck in the muffler. </DIV>
<DIV>&nbsp;</DIV>
<DIV>The high performance Mazda street plugs (turbo plugs) have shielding=
 on the=20
shell ends similar in appearance to some aircraft plugs. They are not airc=
raft=20
plugs. They will not survive hours at full load wide open throttle. The he=
at=20
range is cooler than most street plugs it is true, but nothing like a raci=
ng=20
plug. </DIV>
<DIV>&nbsp;</DIV>
<DIV>Real racing plugs do not have that shielding. They have a welded grou=
nd=20
electrode or a fine wire ground electrode&nbsp;stuck through the side of=
 the=20
shell. They have porcelain filling the shell all the way to the end and ma=
y have=20
a fine wire center electrode. They are as cold a heat range as is possible=
 to=20
produce. They are orders of magnitude colder than the coldest street plug.=
=20
&nbsp;</DIV>
<DIV>&nbsp;</DIV>
<DIV>More later.</DIV>
<DIV>&nbsp;</DIV>
<DIV>Lynn E. Hanover</DIV></FONT></BODY></HTML>

--part1_34b63.6a3a429b.39d61804_boundary--