As far as Lycoming L/TIO 540's are concerned (PA 31) Lycoming do not recommend LOP operation. If you use the figures in the manufacturers handbook (engine) none of them are LOP. Everybody has ideas about engine operation, I, for one, believe that the engine manufacturer know his engine better that anyone. 150 to 300 hrs of operation is NOT a test likely to reveal accelerated wear and tear. Try 1500 to 2000 hrs for some accurate figures. At a replacement price of 65000 oz dollars, a couple of extra litres per hour is sweet F.A. in comparison.
Edited to add this If you can get hold of a publication from lycoming called "Lycoming Flyer Key Reprints" you should. A very interesting read, including leaning, maintenance, and performance tips for all lycoming engines. excellent read for pilots.
Last edited by Dale Harris; 23rd May 2002 at 09:04.