X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail-iw0-f180.google.com ([209.85.214.180] verified) by logan.com (CommuniGate Pro SMTP 5.3.9) with ESMTP id 4488470 for flyrotary@lancaironline.net; Thu, 30 Sep 2010 21:57:47 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.214.180; envelope-from=wdleonard@gmail.com Received: by iwn8 with SMTP id 8so3496748iwn.25 for ; Thu, 30 Sep 2010 18:57:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:received:in-reply-to :references:date:message-id:subject:from:to:content-type; bh=7OqaIkPqUngMR5Rq2+4BY6r+b5WauN/fvw1RJlnOUAA=; b=PRgD8VPlqYZjdVc9x5N+qJryXii29SzqVXio1gEoY3ezEWklHWOY3VtafI0R92MKgh SGHqwjcRcQhwyUAEW2p8QoqpaJfo42bClDLAZ5kyr/o26488AfgZfCuPmX5gJp3QZJep g5QahNaWOPmYpqlrJIhR4XCupCw4sTl6CZebA= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=bUALWIi5p1M+Ql5bZuaF4LuERtY2+K15qoBSGzGoJX32jzwc89qb3qbnWePOxVeYtT 3bV1wgjv4qv8e+649j/gJNnaNh/hXHeIHMw3EI6LaWY2ErrJMfKrGO4YIpwqmJ7v/Cj2 VUSOiV/0y5kxJt8xeyG2MjKJwz1rnxoNJC3zk= MIME-Version: 1.0 Received: by 10.231.182.201 with SMTP id cd9mr4844309ibb.21.1285898231407; Thu, 30 Sep 2010 18:57:11 -0700 (PDT) Received: by 10.231.34.197 with HTTP; Thu, 30 Sep 2010 18:57:11 -0700 (PDT) In-Reply-To: References: Date: Thu, 30 Sep 2010 18:57:11 -0700 Message-ID: Subject: Re: [FlyRotary] Re: New SAG Theory From: David Leonard To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=0016363b85744d19f70491848358 --0016363b85744d19f70491848358 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable I must say that Steve's theory makes sense to me and fits my symptoms. Wit= h my turbo engine, running mostly MOGAS but not too infrequent 100LL as well, I MAYBE get 25 hrs max before the first symptoms start to set in and it gradually gets worse after that. Worse in hot environments, always happens during a high power climb. Glad to hear we may be able to fix it with colder and/or Iridium plugs (platinum too?) BTW, I have seen some effects from what could have been detonation. I have broken 2 side seals. The turbo surely is making the situation worse, but it sure is performing will right now. I recently installed the new turbo with the wastegate actuator in place and reported a disappointing 175KTAS at 6500 RPM after a brief flight. But after some more extensive testing, I can report that I am seeing 190KTAS at 6200 RPM and plenty of throttle left. So it seems I am not under propped after all. I am very sure I can do over 200 KTAS now - if I get up the nerve to flog the turbo and engine that hard. But it comes at a price, wit= h the hot weather here I have had to limit my power a couple times to keep th= e coolant below 200... which is reassuring that my cooling system is actually not over sized... I just needed to install the turbo to discover it. --=20 David Leonard Turbo Rotary RV-6 N4VY http://N4VY.RotaryRoster.net http://RotaryRoster.net On Thu, Sep 30, 2010 at 5:20 PM, Al Gietzen wrote: > I=92ll preface this with the fact that I have never experienced SAG; but= it > is an interesting subject. I don=92t run much 100LL, and I change the plu= gs at > about 40 hours. A couple questions come to mind: > > > > Is all of the discussion of the copper core, etc; relevant to a specific > brand/part# plug? What heat range? > > I use B9EGV racing plugs =96 do they have a copper core? It=92s a fine wi= re > electrode; fairly high heat range number (=91colder=92 plug). > > > > If the issue is preignition =96 is that consistent with the large drop in > EGT? > > > > Al > > > > -----Original Message----- > *From:* Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] *O= n > Behalf Of *Steven W. Boese > *Sent:* Thursday, September 30, 2010 7:14 AM > *To:* Rotary motors in aircraft > *Subject:* [FlyRotary] Re: New SAG Theory Discussions of SAG > > > > Ed, > > > > You take good notes. > > > > Just a couple of clarifications: The decrease in the thermal conductivit= y > of the copper core may be the result of thermal cycling causing developme= nt > of porosity within the copper. This is independent of the corrosion goin= g > on between the Mn alloy electrode sheath and the insulator. So there are > two essentially independent mechanisms contributing to the heat range cha= nge > of the spark plug with age. > > > > The development of the porosity within the copper is not particularly > affected by the type of fuel whereas the corrosion between the Mn alloy > sheath and the insulator is accelerated by the use of 100LL. > > > > The cure is still to install new spark plugs. > > > > I have colder spark plugs from Racing Beat that are recommended for > prolonged use in high RPM high power applications. At best, the colder > plugs will merely delay the onset of SAG but won't prevent it from happen= ing > eventually. It will be some time before the results of using those plugs > will be known. > > > > Steve Boese > > > > > > > ------------------------------ > > *From:* Rotary motors in aircraft [flyrotary@lancaironline.net] On Behalf > Of Ed Anderson [eanderson@carolina.rr.com] > *Sent:* Thursday, September 30, 2010 8:46 AM > *To:* Rotary motors in aircraft > *Subject:* [FlyRotary] New SAG Theory Discussions of SAG > > In a nut shell, Steve's excellent data gathering (how many of use have > access to a scanning electron microscope or spectrum analyzer {:>)) and > analysis indicates a possible alternative reason for SAG other than > fouling. > > > > It basically boils down to a theory of pre-ignition based on the > deteorating heat removal capacity of the plug. > > > > There is a copper core (the photos showing the two cores) in the center o= f > the ceramic cone which is responsible for conducting 90% of the heat away > from the center electrode. Based on Steve's' electron microscope viewing= of > two cores (one new and one having been used in a 100LL environment), it > appears that the plug using leaded gasoline has corrosion occurring on th= e > boundary between this copper core and the surrounding (hot) elements. Th= is > layer of corrosion hinders heat removal from the plug leading to parts of > the plug becoming hot enough to trigger pre-ignition. > > > > This SAG tends to happened at high power settings and reducing power tend= s > to make it go away (for a while). Steve's theory is that the plug > encounters max heat and temperature at high power settings and that reduc= ing > the power permits the plug to cool off enough for the pre-ignition to go > away (for a while). > > > > So we now have two theories - one is the fouled plug and one of the > overheated plug causing SAG. Preignition generally leads to detonation > which does not appear to be happening (at least no one is finding the > typical detonation damage to the rotary engine). A possible reason is th= e > quenching effect of the less than optimum shape of the rotary combustion > space may tend to delay or prevent the onset of detonation damage that on= e > would expect from continuous preignition caused by a too hot plug. > > > > I believe Steve intends to see if he can find some colder plugs (the ones > that conduct heat better) and see if that extends the time between SAG. > Currently I find that roughly 25-30 hours is about the max I can get usin= g > 100LL before SAG sets in, whereas Tracy and others have well over 150 hou= rs > using unleaded Mogas. So if the colder plugs extend the time before SAG,= I > would say that pretty much would suggest Steve's theory is correct - if N= ot, > then perhaps the fouled Plug theory still has merit or it could be some > other phenomena happening. > > > > Steve, my apologies if I did not present your case as well as you could > > > > Ed > > > > Edward L. Anderson > Anderson Electronic Enterprises LLC > 305 Reefton Road > Weddington, NC 28104 > http://www.andersonee.com > http://www.eicommander.com > > > > . > > > > > > > > *From:* Bill Bradburry > > *Sent:* Thursday, September 30, 2010 9:59 AM > > *To:* Rotary motors in aircraft > > *Subject:* [FlyRotary] Discussions of SAG > > > > I understand that there was a presentation on SAG at the meeting. Can > someone go over the alternative theory with the ones of us that were not = in > attendance? It looked like someone had a scanning electron microscope ph= oto > that they were showing! Wow! Are we getting sophisticated or what!! Wa= s > this an explanation of the cause, or ideas for prevention, both?? > > > > Bill B > > > --0016363b85744d19f70491848358 Content-Type: text/html; charset=windows-1252 Content-Transfer-Encoding: quoted-printable I must say that Steve's theory makes sense to me and fits my symptoms.= =A0 With my turbo engine, running mostly MOGAS but not too infrequent 100LL= as well, I MAYBE get 25 hrs max before the first symptoms start to set in = and it gradually gets worse after that.=A0 Worse in hot environments, alway= s happens during a high power climb.

Glad to hear we may be able to fix it with colder and/or Iridium plugs = (platinum too?)

BTW, I have seen some effects from what could have b= een detonation.=A0 I have broken 2 side seals.

The turbo surely is m= aking the situation worse, but it sure is performing will right now.

I recently installed the new turbo with the wastegate actuator in place= and reported a disappointing 175KTAS at 6500 RPM after a brief flight.=A0 = But after some more extensive testing, I can report that I am seeing 190KTA= S at 6200 RPM and plenty of throttle left.=A0 So it seems I am not under pr= opped after all.=A0 I am very sure I can do over 200 KTAS now - if I get up= the nerve to flog the turbo and engine that hard.=A0 But it comes at a pri= ce, with the hot weather here I have had to limit my power a couple times t= o keep the coolant below 200... which is reassuring that my cooling system = is actually not over sized... I just needed to install the turbo to discove= r it.

--
David Leonard

Turbo Rotary RV-6 N4VY
http://N4VY.RotaryRoster.net
http://RotaryRoster.net


On Thu, Sep 30, 2010 at 5:20 PM, Al Gietzen <ALVentures@cox.net> wrote:
=

I=92ll pre= face this with the fact that I have never experienced SAG; but it is an interesting subject. I don= =92t run much 100LL, and I change the plugs at about 40 hours. A couple question= s come to mind:

=A0=

Is all of = the discussion of the copper core, etc; relevant to a specific brand/part# plug? What heat range?=

I use B9EG= V racing plugs =96 do they have a copper core? It=92s a fine wire electrode; fairly high heat range number (=91colder=92 plug).

=A0=

If the iss= ue is preignition =96 is that consistent with the large drop in EGT?

=A0=

Al<= /font>

=A0=

-----Orig= inal Message-----
From: Rotary motors in air= craft [mailto:fl= yrotary@lancaironline.net] On Behalf Of Steven W. Boese
Sent: Thursday, September = 30, 2010 7:14 AM
To: Rotary motors in aircr= aft
Subject: [FlyRotary] Re: N= ew SAG Theory Discussions of SAG

=A0

Ed,

=A0

You take good notes.

=A0

Just a couple of clarifications:=A0 The decrease in the thermal conductivity of the copper core may be the result of thermal cycling=A0causing development of porosity within the copper.=A0 This=A0is independent of the corrosion going on between the Mn alloy electrode sheath and the insulator.=A0 So there are two essentially independent mechanisms contributing to the heat r= ange change of the spark plug with age.=A0

=A0

The development of the porosity within the copper is not particularly affected = by the type of fuel whereas the corrosion between the Mn alloy sheath and the insulator=A0is accelerated by the use of 100LL.

=A0

The cure is still to install new spark plugs.=A0

=A0

I have colder spark plugs from Racing Beat that are recommended for prolonged use=A0in high RPM high power applications.=A0 At best, the colder plugs will merely delay the onset of SAG but=A0won't prevent it from happenin= g eventually.=A0 It will be some time before the results of using those plugs will be known.

=A0

Steve Boese

=A0

=A0=A0

=A0

From: Ro= tary motors in aircraft [flyrotary@lancaironline.net] On Behalf Of Ed Anderson [eanderson@carolina.rr.com]
Sent: Thursday, September = 30, 2010 8:46 AM
To: Rotary motors in aircr= aft
Subject: [FlyRotary] New S= AG Theory Discussions of SAG

In a nut shell, Steve's excellent data gathering (how many of use have access to= a scanning electron microscope or spectrum analyzer {:>)) and analysis indicates a possible alternative reason for SAG other than fouling.=A0

=A0

=A0It basically boils down to a theory of pre-ignition based on the deteorating h= eat removal capacity of the plug.=A0

=A0

There is a copper core (the photos showing the two cores) in the center of the ceram= ic cone which is responsible for conducting 90% of the heat away from the cent= er electrode.=A0 Based on Steve's' electron microscope viewing of two = cores (one new and one having been used in a 100LL environment), it appears that = the plug using leaded gasoline has corrosion occurring on the boundary between = this copper core and the surrounding (hot) elements.=A0 This layer of corrosion hinders heat removal from the plug leading to parts of the plug becoming ho= t enough to trigger pre-ignition.

=A0

This SAG tends to happened at high power settings and reducing power tends to make i= t go away (for a while).=A0 Steve's theory is that the plug encounters max h= eat and temperature at high power settings and that reducing the power permits = the plug to cool off enough for the pre-ignition to go away (for a while).

=A0

So we now have two theories - one is the fouled plug and one of the overheated pl= ug causing SAG.=A0 Preignition generally leads to detonation which does not appear to be happening (at least no one is finding the typical detonation damage to the rotary engine).=A0 A possible reason is the quenching effect = of the less than optimum shape of the rotary combustion space may tend to dela= y or prevent the onset of detonation damage that one would expect from continuou= s preignition caused by a too hot plug.

=A0

I believe Steve intends to see if he can find some colder plugs (the ones tha= t conduct heat better) and see if that extends the time between SAG.=A0 Currently I find that roughly 25-30 hours is about the max I can get using 100LL before SAG sets in, whereas Tracy and others have well over 150 hours using unleaded Mogas.=A0 So if the colder plugs extend the time before SAG, I would say that pretty much would suggest Steve's theory is correct - = if Not, then perhaps the fouled Plug theory still has merit or it could be some oth= er phenomena happening.

=A0

Steve, my apologies if I did not present your case as well as you could

=A0

Ed

=A0

Edward L. Anderson
Anderson Electronic Enterprises LLC
305 Reefton Road
Weddington, NC 28104
http://www.anderson= ee.com
http://www.eicomma= nder.com

=A0

.

=A0

=A0

=A0

Sent: Thursday, September 30, 2010 9:59 AM

Subject: [FlyRotary] Discussions of SAG

=A0

I understand that there was a presentation on SAG at the meeting.=A0 Can someone go over the alternative theory with the ones of us that were not in attendance?=A0 It looked like someone had a scanning electron microscope photo that they were showing!=A0 Wow!=A0 Are we getting sophisticated or what!!=A0 Was this an explanation of the cause, or ideas for prevention, both??<= /p>

=A0

Bill B

=A0





--0016363b85744d19f70491848358--