Return-Path: Received: from [65.33.163.227] (account marv@lancaironline.net) by logan.com (CommuniGate Pro WebUser 4.3c3) with HTTP id 824160 for lml@lancaironline.net; Sat, 26 Mar 2005 21:18:40 -0500 From: "Marvin Kaye" Subject: Re: [LML] Re: Superchargers To: lml X-Mailer: CommuniGate Pro WebUser Interface v.4.3c3 Date: Sat, 26 Mar 2005 21:18:40 -0500 Message-ID: In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset="windows-1252"; format="flowed" Content-Transfer-Encoding: 8bit Posted for "George Braly" : Rob, Our research at GAMI is largely the source of the data which Walter has seen and to which he is referring. As part of this research, about six years ago, I ordered up a complete SDR, Accident report, NTSB report history on every “detonation” or “pre-ignition” related accident or incident in the data base since about 1970. This was/is a stack of printed paper a couple of feet high. I then went through and analyzed all of those, trying to identify and understand the issues. I did this in light of direct evidence we have from operating engines well into medium to heavy detonation for significant periods of time - - without injury to the engine… upon later tear down inspection. The more recent advent of recording downloadable engine monitors has provided a whole series of data files in which there is clearly established pre-ignition - - that resulted in damage to the cylinder that most closely coincides with the description of the damage to the cylinders from almost all of the old accident reports that assert that “detonation” was the cause of the damage to the engine. As it turns out, EI, Insight, & JPI all have erroneous descriptions in their pilot manuals as to what the pilot should see in the event of “detonation”. They even contradict each other and, still, none of them get it right. The fact is - - - pre-ignition is characterized by significantly falling EGT and rapidly rising CHT on a cylinder ( one degree per second or one degree per two seconds). Period. Parade rest. Detonation, mild to moderate detonation - - deliberately induced on the test stand - - results in zero to minimal declines in EGT and a rather gradual increase in CHT (compared to pre-ignition). Spark plugs appear to be a major culprit in pre-ignition. If you drop one - - replace it. If you do have detonation, replace the plugs, as they can be damaged by the detonation… when everything in the cylinder appears to be normal. Regards, George