I find it interesting that this debate even occurs. I worked for many years in the 'experimental engineering' division of a major motor vehicle manufacturer. Now it appears to me that Lyco and Conti would have similar divisions. It also appears to me that some of you are saying that we did not have any idea what we were doing, (despite being employed in this are for many years) and a lot of you know more than the people that actually design and build the equipment. Jabba, I wonder how many people know more about your business than you do. On your standard, a fair few I would guess. (first time I have commented on this debate).
It’s not about what people know.
It’s about what the data prove.
The data prove what settings result in the imposition of the greatest stresses on the engine. The data prove that 40 to 50 F ROP mixture is that setting, exacerbated by reducing RPM with an engine with fixed timing.
It may well be that you and all these divisions in Lyco and Conti know this. But the problem is:
They don’t say this.
It wouldn’t be so bad if they said: “You’re giving your engine the hardest pounding you can give it, at 40 to 50 F ROP and low cruise RPM, but guess what: Our engines are built to take it and we give you a money back guarantee that you’ll make it to TBO!”
It would be even better if they went on to say: “Guess what else? You’ll give your engine less of a pounding if you operate much further ROP, or LOP, and our engine can take even more of that!”
But instead, the persistent folklore results in many engines being operated in the range where they are getting the hardest pounding they can be given.
And when something breaks it is, of course, the pilot’s fault!
And even more appallingly, if you produce engine monitor data to show first hand measurements of the temps running an engine ROP and LOP, and to show that the engine has been run for hundreds of hours at cooler CHTs than they would have been if the engine had been operated ROP, the cylinder failure is
still the pilot’s fault! That cylinder failed because you were running the engine LOP! It wouldn’t have failed if you’d run it (hotter) ROP! It couldn’t possibly a manufacturing or maintenance problem!
This is one of the reasons CMI’s going broke.