lml@lancaironline.net Mailing List Archive

<<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> << Lancair Builders' Mail List >> <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> Bill, How much O2 (as a percent) of the exhaust stream do you think there is in the exhaust stream ? 50F Rich of peak xx % ??? 50F Lean of peak xx % ??? ~ 20%? ~ 10% ~ 50% ~ 5% ~ 2% ~ 1 % ??? That is a starting point. Regardless of the answer to THAT question, consider that there has already been a highly controlled experiment on this subject. For about 400 million engine operating hours, Curtis Wright operated aircraft air cooled piston engines at lean of peak mixture settings. In fact, it was so critical that the engines be operated lean of peak at high cruise power settings that CW would sometimes refuse to honor the warranty if the airlines failed to keep detailed records showing how the engines were operated on each flight. If one reads through all of the old CW engine trouble shooting manuals, there is never even a reference to any kind of problem with exhaust valves due to running lean of peak. In fact, the primary problem they had was when one of the two banks of cylinders ran rich of peak (due to a mechanical linkage adjustment problem between the front and rear bank of jugs). Operating at high power and rich of peak, they routinely cooked off 9 cylinders in one trip to Paris. There is simply no identified engineering reason to believe that all of the same thermodynamic and metallurgical issues that applied to those high powered, steel barreled, aluminum headed, spark ignited, piston engines, do not also apply to your high powered, steel barreled, aluminum headed, spark ignited piston engine. Is there? Regards, George Braly -----Original Message----- From: BILL HANNAHAN [mailto:wfhannahan@yahoo.com] Sent: Sunday, February 03, 2002 2:55 AM To: MAIL LANCAIR Subject: engine dynamics <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> << Lancair Builders' Mail List >> <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> I have enjoyed the discussion on engines, yet the key point that prevents me from running lean of peak has yet to be addressed head on. <SNIP> LML website: http://members.olsusa.com/mkaye/maillist.html LML Builders' Bookstore: http://www.buildersbooks.com/lancair Please remember that purchases from the Builders' Bookstore assist with the management of the LML. Please send your photos and drawings to marvkaye@olsusa.com.