[nucleus]

I have been reading the latest LOP (Lean of Peak) operations thread with a lot of interest; and I went ahead and reread John Deakins' relevant Pelican's Perch columns on the subject as well.

Here is my thought:

I am in process of breaking in my 180 HP Superior IO-360, but it can be hard to maintain higher manifold pressures because of the local terrain, my home field KBZN is at 4500 MSL. If 50 degrees ROP (Rich of Peak) produces the greatest internal pressure and heat, and I want more of both for better break in, then does it make sense to run at 50 ROP when I cannot get my manifold pressure over 24 inches? I understand that above 7500 feet or so you are not generating enough power to damage your engine no matter the mixture. But as long as my temps are okay, should I run 50 ROP in that 6500-7500 to improve my break in?

Hans

 

[erich weaver]

I dont think so - just get as much MAP as you can, keep your RPM up around 2500 and keep away from 50 ROP. The engine will probably just take a little longer than usual to break in. Engine break-in is not the time to begin testing your leaning skills - you can live with 100-200 ROP until break-in cant you?

Deakins articles repeatedly indicate there is no concern about engine damge from improper mixture settings at less than about 60-65% power. That makes good sense to me. However, as pointed out by Kevin Horton on the other thread, it doesnt appear that Deakins statement about power at around 8000 feet being limited to 60-65% is true - at least not for an IO-360engine. 60% of 180 hp is 108 hp. The Lycoming performance chart for my engine (IO-360B1B) idnicates that with full throttle, HP would not be limited to 108 hp until over 12,000 feet under standard conditions.

erich

 

[flyeyes]

I\does it make sense to run at 50 ROP when I cannot get my manifold pressure over 24 inches?
Hans

I think you want to be richer than than for break in. Also, 7500' may be a little low for the "safe" altitude for power settings. I use 9000.

 

[Finley Atherton]

But as long as my temps are okay, should I run 50 ROP in that 6500-7500 to improve my break in?

Hans

If you are going to run at 6,500 to 7,500 ft, and at or near full throttle you will most likely be over the 75% max allowable cruise setting. My non-expert advice is, take off excepted, limit your self to 75% max and follow Lycoming's recommendations: "Maximum Power Cruise" (approx 75% power). Never lean beyond 150 degrees F on the rich side of peak........ Monitor cylinder head temps."

Fin
9A