X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from aspensprings.uwyo.edu ([129.72.10.32] verified) by logan.com (CommuniGate Pro SMTP 6.0c2) with ESMTPS id 5801097 for flyrotary@lancaironline.net; Mon, 08 Oct 2012 13:12:43 -0400 Received-SPF: none receiver=logan.com; client-ip=129.72.10.32; envelope-from=SBoese@uwyo.edu Received: from ponyexpress-ht5.uwyo.edu (extlb.uwyo.edu [172.26.4.4]) by aspensprings.uwyo.edu (8.14.4/8.14.4) with ESMTP id q98HBl78000142 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=FAIL) for ; Mon, 8 Oct 2012 11:12:04 -0600 (MDT) (envelope-from SBoese@uwyo.edu) Received: from ponyexpress-m10.uwyo.edu ([fe80::60dd:cb9e:6f71:3d48]) by ponyexpress-ht5.uwyo.edu ([fe80::addc:5ab0:b0f8:ab9e%13]) with mapi id 14.02.0318.001; Mon, 8 Oct 2012 11:11:15 -0600 From: "Steven W. Boese" To: Rotary motors in aircraft Subject: RE: [FlyRotary] Re: colder spark plugs Thread-Topic: [FlyRotary] Re: colder spark plugs Thread-Index: AQHNpWD5kgS5Quq6q0u5Uh2UZwYsEZevnWbE Date: Mon, 8 Oct 2012 17:11:14 +0000 Message-ID: <3E8191F276108F4481AB0721BBA9269E05DE3CCC@ponyexpress-m10.uwyo.edu> References: In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [75.220.100.163] Content-Type: multipart/alternative; boundary="_000_3E8191F276108F4481AB0721BBA9269E05DE3CCCponyexpressm10u_" MIME-Version: 1.0 --_000_3E8191F276108F4481AB0721BBA9269E05DE3CCCponyexpressm10u_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Ernest, There is no need to take any analysis that I made as correct. The data is = there for interpretation by anyone interested enough to look at it. I think you are on the same theory page as I am. Your proposed modificatio= n to the theory IS the theory. The changes I've seen to the electrode affe= cting thermal conductivity are presented in SAG part 1. The pointlessness = of cleaning SAGGED spark plugs was also pointed out there. The reference to carbon deposits in the main combustion chamber was with th= e intent to indicate that preignition from them would be distinctly differe= nt from preignition originating at the spark plug. I'm sorry if that was n= ot clear. I am not sure that your statement that SAG would decrease the temperature o= f the electrode tip is correct. My contention is that the opposite may occ= ur and that this is the reason that SAG does not cure itself and a change i= n operating conditions is needed to recover from it. It is possible that a colder plug may withstand degredation longer before S= AG occurs. It's my opinion that heat sinks or sources on the insulator on the spark pl= ug wire side would have minimal effect on the temperature of the electrode = tip. The proof, of course, would be to try it and see. I would encourage = you to do so. Steve ________________________________ From: Rotary motors in aircraft [flyrotary@lancaironline.net] on behalf of = Ernest Chrisltey [echristley@att.net] Sent: Monday, October 08, 2012 8:25 AM To: Rotary motors in aircraft Subject: [FlyRotary] Re: colder spark plugs On 10/06/2012 02:12 PM, Steven W. Boese wrote: David, Thank you for the compliment. I have installed a set of the -10 spark plugs and at this point they are lo= ng past the time where the stock plugs normally needed to be replaced. How= long they will continue to work is unknown, but at least that one data poi= nt is consistent with the study and encouraging. Taking your anaylysis as correct, how does a colder plug help? I read the = analysis as saying that carbon deposits build up and glow hot enough to ign= ite combustion early. If it is carbon deposits, will (should?) the heat ra= nge of the plug make a significant difference? http://www.totallyamaha.com/snowmobiles/aaTECH/sparkplug/Spark Plug Informa= tion Overview.htm This page indicates that the plug tip needs to stay between 500*C-800*C. A= ny hotter, and you risk me melting the electrode or blistering the ceramic = insulator. That would account for the "bubbly" appearance to the electrode= in the pictures you posted earlier. An electrode developing bubbles would= become an increasingly better insulator, and trap more heat at the tip. O= nce it traps enough heat to start SAG, the combustion heat drops (due to SA= G), and further melting ceases. The negative feedback will stop the phenom= ena from becoming catastrophic, as long as you have enough runway to clear = the trees. I propose a modification to your theory. The pre-ignition is caused by mec= hanical changes within the electrode of the sparkplug itself, instead of a = carbon deposit. The changes increase the thermal insulation of the plug ti= p. The test for the correctness of this modification to the theory would be to= insulate or heat a new, normal heat range plug in some way. Verify SAG oc= curs. If I am correct, wrapping the porcelain of a plug with nichrome wire= connected to a variable power supply would allow you to create SAG on dema= nd. The significance of this modification is that cleaning the plugs to re= move deposits would be pointless. But it might be possible to use the chea= per plugs with a heat sink to make them last. Rather than purchasing the expensive thin walled socket, a tool was made to= enlarge the spark plug well in the housing so a conventional socket could = be used. While not elegant, this was done with the engine in the plane and= involved minimal expense. I've chucked a cheap socket in the lathe and turned it down to make thin-wa= lled sockets. --_000_3E8191F276108F4481AB0721BBA9269E05DE3CCCponyexpressm10u_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Ernest,

 

There is no need to take any analysis that I made as correct.  The = data is there for interpretation by anyone interested enough to look at it.=

 

I think you are on the same theory page as I am.  Your proposed mod= ification to the theory IS the theory.  The changes I've see= n to the electrode affecting thermal conductivity are presented in SAG part= 1.  The pointlessness of cleaning SAGGED spark plugs was also pointed out there.

 

The reference to carbon deposits in the main combustion chamber was with= the intent to indicate that preignition from them would be distinctly diff= erent from preignition originating at the spark plug.  I'm sorry if th= at was not clear. 

 

I am not sure that your statement that SAG would decrease the temperatur= e of the electrode tip is correct.  My contention is that the opposite= may occur and that this is the reason that SAG does not cure itself and a = change in operating conditions is needed to recover from it.

 

It is possible that a colder plug may withstand degredation longer befor= e SAG occurs.

 

It's my opinion that heat sinks or sources on the insulator on the spark= plug wire side would have minimal effect on the temperature of the electro= de tip.  The proof, of course, would be to try it and see.  I wou= ld encourage you to do so.

 

Steve

 

 

 

 

From: Rotary motors in aircraft [flyrotary= @lancaironline.net] on behalf of Ernest Chrisltey [echristley@att.net]
Sent: Monday, October 08, 2012 8:25 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: colder spark plugs

On 10/06/2012 02:12 PM, Steven W. Boese wrot= e:

David,

 

Thank you for the compliment.

 

I have installed a set of the -10 spark plugs and at this point they are= long past the time where the stock plugs normally needed to be replac= ed.  How long they will continue to work is unknown, but at least that= one data point is consistent with the study and encouraging.


Taking your anaylysis as correct, how does a colder plug help?  I read= the analysis as saying that carbon deposits build up and glow hot enough t= o ignite combustion early.  If it is carbon deposits, will (should?) t= he heat range of the plug make a significant difference?

http://www.totallyamaha.c= om/snowmobiles/aaTECH/sparkplug/Spark Plug Information  Overview.h= tm

This page indicates that the plug tip needs to stay between 500*C-800*C.&nb= sp; Any hotter, and you risk me melting the electrode or blistering the cer= amic insulator.  That would account for the "bubbly" appeara= nce to the electrode in the pictures you posted earlier.  An electrode developing bubbles would become an increasingly better insula= tor, and trap more heat at the tip.  Once it traps enough heat to star= t SAG, the combustion heat drops (due to SAG), and further melting ceases.&= nbsp; The negative feedback will stop the phenomena from becoming catastrophic, as long as you have enough runway to= clear the trees.

I propose a modification to your theory.  The pre-ignition is caused b= y mechanical changes within the electrode of the sparkplug itself, instead = of a carbon deposit.  The changes increase the thermal insulation of t= he plug tip. 

The test for the correctness of this modification to the theory would be to= insulate or heat a new, normal heat range plug in some way.  Verify S= AG occurs.  If I am correct, wrapping the porcelain of a plug with nic= hrome wire connected to a variable power supply would allow you to create SAG on demand.  The significance of this mo= dification is that cleaning the plugs to remove deposits would be pointless= .  But it might be possible to use the cheaper plugs with a heat sink = to make them last.

 

Rather than purchasing the expensive thin walled socket, a tool was= made to enlarge the spark plug well in the housing so a conventional socke= t could be used.  While not elegant, this was done with the engin= e in the plane and involved minimal expense.

 


I've chucked a cheap socket in the lathe and turned it down to make thin-wa= lled sockets.
--_000_3E8191F276108F4481AB0721BBA9269E05DE3CCCponyexpressm10u_--