Larry DeCamp
Well Known Member
I asked Superior engines if leaded fuel was required for breakin and valve health for my IO EXP 360. Here is the answer I received :
"There is no metallurgical benefit to operating the engine during break-in on leaded aviation gasoline as relates to valve or valve seat lubrication. However, the brake mean effective pressure (BMEP) will be increased with the use of leaded aviation gasoline (AvGas). The slower burn rate of avgas compared to auto fuel will allow for a more efficient use of the ignited fuels pressure buildup to be converted to mechanical energy instead of heat. While not specifically noted, you may want to ensure the engine is operated on AvGas for the first 25 hours to ensure the highest BMEP during this time. Higher BMEP will assist in ring set and ensure a good rings seal."
While this is thought provoking, it does raise the question how much BMEP is your engine developing ( set aside MP/RPM setting ) considering magneto fixed timing, Pmag aggressive timing and EI adjustable timing ??
I hope this helps others like me that were "unfulfilled" by opinions on the Leaded Break-in Wives Tail.
"There is no metallurgical benefit to operating the engine during break-in on leaded aviation gasoline as relates to valve or valve seat lubrication. However, the brake mean effective pressure (BMEP) will be increased with the use of leaded aviation gasoline (AvGas). The slower burn rate of avgas compared to auto fuel will allow for a more efficient use of the ignited fuels pressure buildup to be converted to mechanical energy instead of heat. While not specifically noted, you may want to ensure the engine is operated on AvGas for the first 25 hours to ensure the highest BMEP during this time. Higher BMEP will assist in ring set and ensure a good rings seal."
While this is thought provoking, it does raise the question how much BMEP is your engine developing ( set aside MP/RPM setting ) considering magneto fixed timing, Pmag aggressive timing and EI adjustable timing ??
I hope this helps others like me that were "unfulfilled" by opinions on the Leaded Break-in Wives Tail.