X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from [24.25.9.101] (HELO ms-smtp-02-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 5.0c2) with ESMTP id 711571 for flyrotary@lancaironline.net; Mon, 05 Sep 2005 08:14:03 -0400 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.101; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-065-188-083-049.carolina.res.rr.com [65.188.83.49]) by ms-smtp-02-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id j85CDFl9024281 for ; Mon, 5 Sep 2005 08:13:16 -0400 (EDT) Message-ID: <000901c5b212$efbd6750$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Another great flying day = another day of troubleshooting Date: Mon, 5 Sep 2005 08:11:24 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0006_01C5B1F1.68701DE0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_0006_01C5B1F1.68701DE0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Ed Wrote: =20 Hi Dave, Thanks for the reports, I don't feel so lonesome {:>).=20 Regarding SAG - my analysis is that susceptibility to SAG is = proportional to combustion chamber pressure at ignition and the = condition of the plugs. The more pressure - the harder it is for the = spark to jump the gap, so if your plugs are getting coated with = lead/carbon, I would expect to see more SAG with More manifold pressure. = Tracy and I have found the same thing (unturboed). At high power = setting (higher manifold pressure) the problem becomes more aggravated. = Reducing throttle setting helped - but, replacing (perhaps cleaning the = spark plug center ceramic cone) is the cure. I must have a fortune in = little-used spark plugs setting around waiting for me to have nothing = else to do but clean spark plugs {:>).=20 Ok, that fits except for the fact that at increasing altitudes, the = MAP at which the SAG occurred was lower (eg. 36" at s.l. but only 26" at = 10k'). So something else is involved but I don't know what. Time to = order more spark plugs. :-)=20 =20 Actually, Dave you had a higher pressure ratio (manifold to ambient) = at 10,000 feet with 26" boost than at sea level with 36". At sea level = the pressure ratio would be 36/29.92 =3D 1.20. At 10,000 ft ambient = pressure =3D 20.57 " hg , so the pressure ratio would be 26/20.57 =3D = 1.26. Not much greater, but it was higher by approx.1.23" Hg. (1.20 = -1.26 =3D .06 *20.57 =3D 1.234" Hg).=20 Ed A ------=_NextPart_000_0006_01C5B1F1.68701DE0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Ed Wrote:

Hi Dave,

Thanks for the reports, I don't feel so = lonesome=20 {:>).

Regarding SAG - my analysis is that=20 susceptibility to SAG is proportional to combustion chamber pressure = at=20 ignition and the condition of the plugs. The more pressure = - the=20 harder it is for the spark to jump the gap, so if your plugs are = getting=20 coated with lead/carbon, I would expect to see more SAG with More = manifold=20 pressure. Tracy and I have found the same thing = (unturboed). At=20 high power setting (higher manifold pressure) the problem becomes = more=20 aggravated. Reducing throttle setting helped - but, replacing = (perhaps=20 cleaning the spark plug center ceramic cone) is the cure. I = must have=20 a fortune in little-used spark plugs setting around waiting for me = to have=20 nothing else to do but clean spark plugs {:>). =

Ok, that fits except for the fact that at increasing altitudes, = the MAP=20 at which the SAG occurred was lower (eg. 36" at s.l. but only 26" at=20 10k'). So something else is involved but I don't know = what. =20 Time to order more spark plugs. :-)

Actually, Dave you had a higher pressure ratio (manifold to = ambient)=20 at 10,000 feet with 26" boost than at sea level with 36". At sea = level=20 the pressure ratio would be 36/29.92 =3D 1.20. At 10,000 ft = ambient=20 pressure =3D 20.57 " hg , so the pressure=20 ratio would be 26/20.57 =3D 1.26. Not much = greater,=20 but it was higher by approx.1.23" Hg. (1.20 -1.26 =3D .06 *20.57 =3D = 1.234" Hg).=20

Ed A

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