X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 10 [X] Return-Path: Received: from bay0-omc3-s5.bay0.hotmail.com ([65.54.246.205] verified) by logan.com (CommuniGate Pro SMTP 5.1.7) with ESMTP id 1924726 for flyrotary@lancaironline.net; Fri, 16 Mar 2007 12:16:31 -0400 Received-SPF: pass receiver=logan.com; client-ip=65.54.246.205; envelope-from=lors01@msn.com Received: from hotmail.com ([65.54.250.87]) by bay0-omc3-s5.bay0.hotmail.com with Microsoft SMTPSVC(6.0.3790.2668); Fri, 16 Mar 2007 09:15:45 -0700 Received: from mail pickup service by hotmail.com with Microsoft SMTPSVC; Fri, 16 Mar 2007 09:15:45 -0700 Message-ID: Received: from 4.171.174.176 by BAY115-DAV15.phx.gbl with DAV; Fri, 16 Mar 2007 16:15:42 +0000 X-Originating-IP: [4.171.174.176] X-Originating-Email: [lors01@msn.com] X-Sender: lors01@msn.com From: "Tracy Crook" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Engine noise and changes in timeing and mixture. Date: Fri, 16 Mar 2007 12:15:34 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0177_01C767C4.CC8F9000" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: MSN 9 X-MimeOLE: Produced By MSN MimeOLE V9.50.0034.2000 Seal-Send-Time: Fri, 16 Mar 2007 12:15:34 -0400 X-OriginalArrivalTime: 16 Mar 2007 16:15:45.0545 (UTC) FILETIME=[5A1EB790:01C767E6] Return-Path: lors01@msn.com This is a multi-part message in MIME format. ------=_NextPart_000_0177_01C767C4.CC8F9000 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Maybe not, Bill. Without the snubbers, there would be some unknown and=20 possibly variable delay in the closing. There would also possibly be=20 varying delays between different injectors. This variability might not=20 be enough to feel a vibration, but the exhaust pulse would be slightly=20 stronger from one chamber than the other. It would only be detected as=20 more noise and would express itself as a slop factor in tuning. Remove=20 the variability and the tuning can be more exact since the same amount=20 of fuel will be delivered every time, giving Tracy that extra 100RPM. Possible? =20 ,|"|"|, Ernest Christley | Possible as anything else I can think of right now. The 'variability' = theory could explain a lot. I know that the *average* mixture is the = same as before (after correcting the IPW) but it is quite possible that = there was a lot of jitter in the pulse width causing cycle to cycle = mixture to vary a lot which the mixture monitor would not show. I hesitate to throw more non-engineering terms into the discussion but = sometimes those are the only clues we have to start with. The engine = does seem "crisper" and more responsive to throttle changes. Very = interesting that Steve perceived a similar change in engine noise too.=20 Tracy (back from more house renovation) ------=_NextPart_000_0177_01C767C4.CC8F9000 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Maybe not, Bill. Without the snubbers, there would be = some=20 unknown and
possibly variable delay in the closing. There = would also=20 possibly be
varying delays between different injectors. This=20 variability might not
be enough to feel a vibration, but the exhaust = pulse=20 would be slightly
stronger from one chamber than the other. It = would=20 only be detected as
more noise and would express itself as a slop = factor in=20 tuning. Remove
the variability and the tuning can be more = exact since=20 the same amount
of fuel will be delivered every time, giving Tracy = that=20 extra=20 100RPM.

Possible?

= ; =20 ,|"|"|, = =20 Ernest Christley |

Possible as anything else I can think of right now. The = 'variability'=20 theory could explain a lot. I know that the *average* mixture is = the same=20 as before (after correcting the IPW) but it is quite possible that there = was a=20 lot of jitter in the pulse width causing cycle to cycle mixture to vary = a=20 lot which the mixture monitor would not show.

I hesitate to throw more non-engineering terms into the = discussion but=20 sometimes those are the only clues we have to start with. The = engine does=20 seem "crisper" and more responsive to throttle changes. Very=20 interesting that Steve perceived a similar change in engine noise=20 too.

Tracy (back from more house renovation) =20

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