Return-Path: Received: from [69.171.52.140] (account marv@lancaironline.net) by logan.com (CommuniGate Pro WebUser 4.3c3) with HTTP id 829373 for lml@lancaironline.net; Tue, 29 Mar 2005 22:06:12 -0500 From: "Marvin Kaye" Subject: Re: [LML] George or Craig for combined wisdom To: lml X-Mailer: CommuniGate Pro WebUser Interface v.4.3c3 Date: Tue, 29 Mar 2005 22:06:12 -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" : Yes. Maybe 95% 100LL and 5% 92(R + M)/2. Seriously… the TSIO-550 at 350 Hp is one of the three or four most difficult engines with respect to detonation, after two or three Lycoming 350 Hp engines. It is not a vapor pressure issue. It *IS* an octane issue. The vapor pressure is mostly a climb to altitude without vapor lock issue. Yes… I have blended fuels and do have dyno results in a variety of combinations. But there is superb published data on a lot of this. I can run a 350 Hp TIO or TSIO engine to only about 210 to 230 Hp on premium car gas. Then all hell breaks loose. Not a pretty sight. And that is at modest CHTs. Add on hot day or altitude conditions and it gets worse. We can run the most difficult engine in the fleet (TIO-540J2B) with PRISM under hot day certification conditions and do that on unleaded Avgas. MON about 92. But that is a very different fuel than 92 (R+M)/2 car gas, which has a MON of about 87. Regards, George _____ From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of John W. Cox Sent: Tuesday, March 29, 2005 8:20 PM To: Lancair Mailing List Subject: [LML] George or Craig for combined wisdom With your combined knowledge of mechanical engine function can you address the following? Is their a point (Mixing Ratio) of combining 100LL AVGAS with 92RON or better MOGAS that the Reid Pressure Number stays low enough that Pre-Ignition or Detonation is not a factor in the Continental TSIO-550, TNIO-550, IO-550 or an M14P Radial. With the fluctuating price of refined fuels and talk of mixing these or using auto engines (alternatives), it has me wondering. I had heard mention that the radials can handle a blend. Have you ever obtained dyno results on blended fuels with these powerplants? Is this a potential with the PRISM system? John W. Cox [ I through the PRISM "mags" wouldn't fit on an overhead induction cont like the TSIO-550 and IO-550 ?? -Rob ]