X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fed1rmmtao101.cox.net ([68.230.241.45] verified) by logan.com (CommuniGate Pro SMTP 5.1.12) with ESMTP id 2336584 for flyrotary@lancaironline.net; Mon, 17 Sep 2007 20:22:34 -0400 Received-SPF: none receiver=logan.com; client-ip=68.230.241.45; envelope-from=alventures@cox.net Received: from fed1rmimpo02.cox.net ([70.169.32.72]) by fed1rmmtao101.cox.net (InterMail vM.7.08.02.01 201-2186-121-102-20070209) with ESMTP id <20070918002156.OABN9743.fed1rmmtao101.cox.net@fed1rmimpo02.cox.net> for ; Mon, 17 Sep 2007 20:21:56 -0400 Received: from BigAl ([72.192.143.193]) by fed1rmimpo02.cox.net with bizsmtp id pcMw1X00P4AaN600000000; Mon, 17 Sep 2007 20:21:56 -0400 From: "Al Gietzen" To: "'Rotary motors in aircraft'" Subject: One for the guys that don't give up Date: Mon, 17 Sep 2007 17:22:12 -0800 Message-ID: <000001c7f992$57893620$6401a8c0@BigAl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0001_01C7F94F.4965F620" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6626 Importance: Normal In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3138 This is a multi-part message in MIME format. ------=_NextPart_000_0001_01C7F94F.4965F620 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable I don't seldom give up on a problem, but I came awfully close this time. Mark OK; Mark; (or anybody). Since we both have 20Bs, and both use the EC2 controller, maybe you have a clue for this one. I've brought this up = here before, but no solution. I have all the latest updates on the EC2, and I have double checked the static timing set at 35o BTDC. From that point on the EC2 is handling = the timing curve with rpm and MAP. At lower power levels, disabling the leading ignition clearly has a = larger effect than disabling the trailing - as one would expect. At somewhere around 18" MAP, (don't know right now what rpm that is, maybe close to = 4000) the effect is about equal when disabling either set. At higher power levels, there is a larger effect of disabling the trailing than the = leading. That troubles me. I think the leading should always have a greater = effect. It makes me wonder about the timing; or if something else is wrong.=20 I have in the past tried varying the timing 2 or 3 steps while at power, = but couldn't discern a change in rpm greater than the normal variation in = the readout. Tracy sent me the XL spreadsheet with the timing curve data, = but I haven't yet figured a safe way of checking it with that prop spinning = close by. Does your installation exhibit the same behavior? Is there some = explanation for this? What test should I perform? One thing that occurs to me is that Tracy measures MAP out before the runners. I measure MAP at the manifold, downstream from intake plenum = and three short runners and the 3-barrel TWM throttle body. At WOT my MAP = is not atmospheric pressure - it is maybe 2-3" HG less. I can't quite see = how that is an issue; but maybe someone else with a TWM TB setup with the = MAP port downstream would know. =20 Other than that I'm very pleased with the new mixture correction table = setup for the 20B. Much less tuning and seamless transistion between tables = and through the stage point. Probably the pulse clamping and injector = isolation diodes are part of that. ------=_NextPart_000_0001_01C7F94F.4965F620 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable


I don't seldom give up on a problem, but I came awfully close this = time.

Mark

OK; Mark; (or = anybody).  Since we both have 20Bs, and both use the EC2 controller, maybe = you have a clue for this one. I’ve brought this up here before, but no = solution.

I have all the latest updates on = the EC2, and I have double checked the static timing set at 35o = BTDC.  From that point on the EC2 is handling the timing curve with rpm and = MAP.

At lower power levels, disabling = the leading ignition clearly has a larger effect than disabling the trailing = – as one would expect.  At somewhere around 18” MAP, = (don’t know right now what rpm that is, maybe close to 4000) the effect is about = equal when disabling either set.  At higher power levels, there is a larger = effect of disabling the trailing than the leading.  That troubles me.  I = think the leading should always have a greater effect.  It makes me = wonder about the timing; or if something else is wrong.

I have in the past tried varying = the timing 2 or 3 steps while at power, but couldn’t discern a change = in rpm greater than the normal variation in the readout.  Tracy sent me the = XL spreadsheet with the timing curve data, but I haven’t yet figured = a safe way of checking it with that prop spinning close by.

Does your installation exhibit = the same = behavior?  Is there some explanation for this?  What test should I = perform?

One thing that occurs to me is = that Tracy measures MAP = out before the runners.  I measure MAP at the manifold, downstream from = intake plenum and three short runners and the 3-barrel TWM throttle body.  = At WOT my MAP is not atmospheric pressure – it is maybe 2-3” HG = less.  I can’t quite see how that is an issue; but maybe someone else with = a TWM TB setup with the MAP port downstream would know.

 

Other than that I’m very = pleased with the new mixture correction table setup for the 20B.  Much less = tuning and seamless transistion between tables and through the stage point. =  Probably the pulse clamping and injector isolation diodes are part of = that.

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