X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from smtp811.mail.sc5.yahoo.com ([66.163.170.81] verified) by logan.com (CommuniGate Pro SMTP 4.3c5) with SMTP id 934266 for flyrotary@lancaironline.net; Thu, 05 May 2005 22:39:23 -0400 Received-SPF: none receiver=logan.com; client-ip=66.163.170.81; envelope-from=dcarter@datarecall.net Received: from unknown (HELO Davidscmptr) (dcarter11@sbcglobal.net@66.138.56.210 with login) by smtp811.mail.sc5.yahoo.com with SMTP; 6 May 2005 02:38:37 -0000 Message-ID: <15c401c551e4$b10deb80$6401a8c0@ip.net> Reply-To: "David Carter" From: "David Carter" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: EGT temps Date: Thu, 5 May 2005 21:38:30 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_15C1_01C551BA.C7655140" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1409 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1409 This is a multi-part message in MIME format. ------=_NextPart_000_15C1_01C551BA.C7655140 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MessageRusty, good point about treating your exhaust kindly - that is = about the only valid reason for "cooling the EGT". I think we agree it = is not an issue of engine "running badly" or "hurting engine" - just = hurting the [non-Inconel or non-titanium] exhaust pipes. It always happens - I make a dogmatic statement - and get to learn = something I hadn't thought of before! I'm thinking if mine were to run that hot, I'd just back off the = throttle (or lean aggressively) to cool the EGT to whatever I thought = the exh system would tolerate ddurig climb (or race) - but wouldn't = change a thing about the engine, timing etc. Hmmm - I wonder about = timing. Once I built up a VW engine for use in an airplane - put it back in my = VW Bus and cranked it up for first time - exhaust smoked and eventually = the "undercoating" (petroleum based) that I'd sprayed under car to = protecte from salt and snow in Des Moines, Iowa, caught fire!! I hadn't = thought the engine was running quite right - then it dawned on me: The = timing was way RETARDED - firing too late - and lots of stuff burning at = flame temp IN THE MUFFLER (a Kadron extractor). That's why it was so = hot. When I rechecked the timing and got it set correctly, the "high = EGTs" went away - no more smoking and fires back there. Ran it another = eighty thousand miles in the bus (didn't build the Vari-Eze). So, could "timing being retarded/firing too late" cause "higher than = normal EGT"? Anyone else think there might be a timing problem if = someone reports "higher than other folks' EGT"? Not making a "dogmatic = statement" this time, just asking for a sanity check or other = operational anecdotes. David ----- Original Message -----=20 From: Russell Duffy=20 To: Rotary motors in aircraft=20 Sent: Wednesday, May 04, 2005 9:47 AM Subject: [FlyRotary] Re: EGT temps So, I believe there is no such thing as "EGT too high". There is only = "peak EGT", whatever it is for your installation. Hi David, Everything you said sounds right to me, with a note that the (NA) rotary = can run way lean of peak, and not be damaged. This is actually a neat = phenomenon. You can climb to cruise altitude, and leave the throttle = wide open, then use the mixture almost as a throttle. =20 I would also have to note that EGT can be too high. Mine will easily = exceed 1800 degrees, and I don't think I'd want to do that to my exhaust = system very long. =20 Cheers, Rusty ------=_NextPart_000_15C1_01C551BA.C7655140 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message
Rusty, good point about treating your = exhaust=20 kindly - that is about the only valid reason for "cooling the = EGT".  I=20 think we agree it is not an issue of engine "running badly" or "hurting = engine"=20 - just hurting the [non-Inconel or non-titanium] exhaust = pipes.
 
It always happens - I make a dogmatic = statement -=20 and get to learn something I hadn't thought of before!
 
I'm thinking if mine were to run that = hot, I'd just=20 back off the throttle (or lean aggressively)  to cool the EGT to = whatever I=20 thought the exh system would tolerate ddurig climb (or race) - but = wouldn't=20 change a thing about the engine, timing etc.  Hmmm - I wonder about = timing.
 
Once I built up a VW engine for use in = an airplane=20 - put it back in my VW Bus and cranked it up for first time - exhaust = smoked and=20 eventually the "undercoating" (petroleum based) that I'd sprayed under = car to=20 protecte from salt and snow in Des Moines, Iowa, caught fire!!  I = hadn't=20 thought the engine was running quite right - then it dawned on me:  = The=20 timing was way RETARDED - firing too late - and lots of stuff burning at = flame=20 temp IN THE MUFFLER (a Kadron extractor).  That's why it was so = hot. =20 When I rechecked the timing and got it set correctly, the "high EGTs" = went away=20 - no more smoking and fires back there.  Ran it another eighty = thousand=20 miles in the bus (didn't build the Vari-Eze).
 
So, could "timing being retarded/firing = too late"=20 cause "higher than normal EGT"?  Anyone else think there might be a = timing=20 problem if someone reports "higher than other folks' EGT"?  Not = making a=20 "dogmatic statement" this time, just asking for a sanity check or other=20 operational anecdotes.
 
David
 
----- Original Message -----=20
From: Russell Duffy=20
Sent: Wednesday, May 04, 2005 9:47 AM
Subject: [FlyRotary] Re: EGT temps

So, I believe there is no such thing as = "EGT too=20 high".  There is only "peak EGT", whatever it is for  your=20 installation.
 
 
Hi=20 David,
 
Everything=20 you said sounds right to me, with a note that the (NA) rotary can run = way lean=20 of peak, and not be damaged.  This is actually a neat = phenomenon.  You=20 can climb to cruise altitude, and leave the throttle wide open, then use = the=20 mixture almost as a throttle. 
 
I would also=20 have to note that EGT can be too high.  Mine will easily exceed = 1800=20 degrees, and I don't think I'd want to do that to my exhaust system very = long. 
 
Cheers,
Rusty
 
------=_NextPart_000_15C1_01C551BA.C7655140--