Return-Path: Sender: "Marvin Kaye" To: lml@lancaironline.net Date: Mon, 17 Jan 2005 12:47:11 -0500 Message-ID: X-Original-Return-Path: Received: from wind.imbris.com ([216.18.130.7] verified) by logan.com (CommuniGate Pro SMTP 4.2.8) with ESMTP-TLS id 610279 for lml@lancaironline.net; Mon, 17 Jan 2005 12:42:38 -0500 Received-SPF: none receiver=logan.com; client-ip=216.18.130.7; envelope-from=brent@regandesigns.com Received: from [192.168.1.100] (wireless-216-18-135-19.imbris.com [216.18.135.19]) (authenticated bits=0) by wind.imbris.com (8.12.11/8.12.11) with ESMTP id j0HHf1lB092033 for ; Mon, 17 Jan 2005 09:42:06 -0800 (PST) (envelope-from brent@regandesigns.com) X-Original-Message-ID: <41EBF8A9.9010507@regandesigns.com> Disposition-Notification-To: Brent Regan X-Original-Date: Mon, 17 Jan 2005 09:40:57 -0800 From: Brent Regan User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.2) Gecko/20040804 Netscape/7.2 (ax) X-Accept-Language: en-us, en MIME-Version: 1.0 X-Original-To: Lancair Subject: Re: IV-P continental detonation Content-Type: multipart/alternative; boundary="------------080606040803050308070708" This is a multi-part message in MIME format. --------------080606040803050308070708 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit I agree with George and Charlie that Andre's experience was not detonation, which would not manifest as a single big bang. Compressor stall would produce the perceived noise without a combustion event in the exhaust system but the engine's "E" designation and the rough running before the event point to ignition or fuel. No big leap of insight here as an engine needs three "consumables" to produce power, air, fuel & spark, so if it aint air it's gotta be one of the other two. One thing I would add to check, based on the comment "one loud bang lasting 1 second", is the fuel system. A second is a long time for an ignition problem. I would think it is not a problem with a clogged filter or screen because this would not cause a transient event and the flow rates are much higher during takeoff. A balky pressure regulator, relief valve or fuel pump could be the problem but, given the Wx lately, my guess (emphasis on guess) is either fuel contamination, specifically water or low vapor pressure pressure (winter gas) combined with the warm (-10C) OAT to cause fuel pump cavitation. A thorough check of air, fuel and ignition systems IS in order. Regards Brent Regan --------------080606040803050308070708 Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit I agree with George and Charlie that Andre's experience was not detonation, which would not manifest as a single big bang. Compressor stall would produce the perceived noise without a combustion event in the exhaust system but the engine's "E" designation and the rough running before the event point to ignition or fuel. No big leap of insight here as an engine needs three "consumables" to produce power, air, fuel & spark, so if it aint air it's gotta be one of the other two.

One thing I would add to check, based on the comment "one loud bang lasting 1 second", is the fuel system. A second is a long time for an ignition problem. I would think it is not a problem with a clogged filter or screen because this would not cause a transient event and the flow rates are much higher during takeoff. A balky pressure regulator, relief valve or fuel pump could be the problem but, given the Wx lately, my guess (emphasis on guess) is either fuel contamination, specifically water or low vapor pressure pressure (winter gas) combined with the warm (-10C) OAT to cause fuel pump cavitation.

A thorough check of air, fuel and ignition systems IS in order.

Regards
Brent Regan
--------------080606040803050308070708--