** [ green amber red blue ] do you remember those colors well the lead helped lub the engine as well .I think the heat is destroying these engines through several issues**
Heat is a bad thing. The hottest possible mixture is 40dF ROP. Anything else is cooler.
** Lean of peak, poor induction air cooling and no lead additive**
Lead is in the fuel to improve detonation margin. It has no other function. It is NOT a lubricant in any manner. Bromide is placed in the fuel to act as a scavenger of the lead to get it out of the induction chamber. Lead exists during the combustion event as a salt of bromide--lead-oxy-bromide. It becomes a vapor at 1305dF so with a combustion temperature of 3800dF or so, it doesn't hang around. If it did, it is a salt. Salts are abrasive. Abrasives make very poor lubricants.
**I really think the best way to tell if you are going to far into lean of peak is look at all the blue parts that are in the engine at break down **
That would imply that running LOP generates heat. The converse is true. LOP operation at the same HP as ROP operation WILL be generating LESS heat.
**Everyone seems to want the lean of peak and I don’t understand that other than the fuel cost. I guess do what you think is best fuel cost or engine brake down at half tbo the real question is are you making the tbo and I have heard of only a few that can say they are These engines were certified back when fuel was leaded and the numbers represent cert not 100ll
My best guess on total times is 2500 hrs in c 206/ c 210 and 7500 hrs in other cessna 150 through 421 all this time was in the late 60’s and 70’s
My thoughts are only mine so when you brake down at less than 500 hr maybe you are running to lean also maybe we should get a chart of actually who is running lean of peak with gami and cert and the actual hrs it ran before brake down on the whole fleet Bill Maddox**
Bill, there are over 400 MILLION flight hours of data on this subject in big radials and over 5 MILLION flight hours of LOP operation in today's flat engines. The LOP run engines run cooler, the oil stays cleaner longer and the engines operate under less pressure stress. Heat and pressure are the enemies of metal. LOP ops have the advantage of both. Again, 40dF ROP is the mixture that will guarantee the highest heat and pressure in the engine.