X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from imo-d04.mx.aol.com ([205.188.157.36] verified) by logan.com (CommuniGate Pro SMTP 4.3c5) with ESMTP id 932338 for flyrotary@lancaironline.net; Wed, 04 May 2005 12:13:52 -0400 Received-SPF: pass receiver=logan.com; client-ip=205.188.157.36; envelope-from=WRJJRS@aol.com Received: from WRJJRS@aol.com by imo-d04.mx.aol.com (mail_out_v38_r1.7.) id q.155.5003d625 (4394) for ; Wed, 4 May 2005 12:13:01 -0400 (EDT) From: WRJJRS@aol.com Message-ID: <155.5003d625.2faa4e8c@aol.com> Date: Wed, 4 May 2005 12:13:00 EDT Subject: Re: [FlyRotary] Re: EGT temps To: flyrotary@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1115223180" X-Mailer: 9.0 SE for Windows sub 5012 -------------------------------1115223180 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 5/4/2005 6:52:57 AM Pacific Standard Time, dcarter@datarecall.net writes: A point I like to think of is that 50 or 80 degrees "from" "peak" on the rich side and on the lean side is, the same temperature. For piston engines, running 50 deg lean of peak is the same temp as running 50 deg rich of peak, so the valves are seeing the same temp - so why are some engine "gurus" so adament about cruising 50 deg rich of peak? It makes no sense to me David, This subject could qualify as a "never ending debate" issue. There are true economys to be found by running lean of peak. But there is a danger if running lean of peak and climbing you can get into an area very dangerous for detonation. Running up the "backside" of the leanness curve can cause overtemps in a piston engine very easily. Exhaust valve failure is a real danger. Rotary wise we are safer than piston pushers since the large amount of heat transfer area keeps us safer. Detonation is still possible so caution is recomended. My EAA chapter was visited by Lycon a Lyc engine builder of good rep in our area. Steve from Lycon mentioned that there has been a lot of variance in avgas with large changes in formulation form area to area. They tested avgas in several western states and found enough difference that they wouldn't warranty their engines if run lean of peak (at all) although I don't know how they would be able to prove you were operating in that mode! Bill Jepson -------------------------------1115223180 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable
In a message dated 5/4/2005 6:52:57 AM Pacific Standard Time,=20 dcarter@datarecall.net writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>A point I like to think of is that 50 or 80 degrees=20= "from"=20 "peak" on the rich side and on the lean side is, the same temperature.&nbs= p;=20 For piston engines, running 50 deg lean of peak is the same temp as runnin= g 50=20 deg rich of peak, so the valves are seeing the same temp - so why are=20 some engine "gurus" so adament about cruising 50 deg rich of=20 peak?  It makes no sense to me
David,
 This subject could qualify as a "never ending debate" issue. Ther= e=20 are true economys to be found by running lean of peak. But there is a danger= if=20 running lean of peak and climbing you can get into an area very dangerous fo= r=20 detonation. Running up the "backside" of the leanness curve can cause overte= mps=20 in a piston engine very easily. Exhaust valve failure is a real danger. Rota= ry=20 wise we are safer than piston pushers since the large amount of heat transfe= r=20 area keeps us safer. Detonation is still possible so caution is recomended.=20
My EAA chapter was visited by Lycon a Lyc engine builder of good rep in= our=20 area. Steve from Lycon mentioned that there has been a lot of variance in av= gas=20 with large changes in formulation form area to area. They tested avgas in=20 several western states and found enough difference that they wouldn't warran= ty=20 their engines if run lean of peak (at all) although I don't know how they wo= uld=20 be able to prove you were operating in that mode!
Bill Jepson
 
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