Pierre's post is a good one. I would point out (and correct me if I'm wrong, Pierre) that the turbo normalized Cirrus installations were originally done by Tornado Alley....the GAMI guys, and the "gurus" of LOP. I've heard the story that Pierre noted before, and it's interesting to note that most of the Cirrus owners operating those turbo normalized engines were in fact fairly closely following Tornado Alley's operating recommendations, I believe.

In other words, there's information out there that may or may not apply to every engine.

Another example: The four cylinder Lycoming engines, and what the hell, the six cylinder Lycs with carburetors.....For decades, we all operated those engines the way Lycoming said to operate them: Without "proper" engine instrumentation, you avoided leaning above 75 % power, and when you did lean the mixture, you leaned by ear...pull the mixture out till the engine stumbles, then push the mixture back in "a ways" to engine smoothness.

First time I ran one of these engines with an engine analyzer, I was curious to see where that procedure got me to regarding EGTs. The answer is, just slightly rich of peak EGT. Like, JUST slightly rich of peak.

So, what's my point? The point is, I've run several of these engines to TBO and beyond without ever having a cylinder off, using that procedure. Red fin???? Really?

Continental engines and Lycoming engines are VERY different beasts.

I have no fear of that "red fin" as far as leaning goes, but I will not lean an engine if its putting out more than 75% power.

MTV

mtv wrote:
Continental engines and Lycoming engines are VERY different beasts.

I have no fear of that "red fin" as far as leaning goes, but I will not lean an engine if its putting out more than 75% power.

MTV

X2

If I remember correctly, the red fin on lycomings disappears below 75% power.

mtv wrote:Continental engines and Lycoming engines are VERY different beasts.

They are different, but surely all the cylinder head cares about is the pressure of the combustion event. Which boils down to air-fuel ratio and the compression ratio.

If the combustion event goes beyond a certain point, detonation starts.

You were probably running the engine with some detonation far into TBO, some light detonation isn't a bad thing for an engine. Or maybe not, it all depends where your engine runs smooth - could be at peak, could be ROP, could be LOP... without an engine analyzer, you have to rely on a mixture of good luck and practices which are known to work in most situations.

Still, personally I would rather understand the science behind the red fin, than guess and wait to see if I make TBO through luck.

Oh, I agree. Just pointing out that not everything asserted on the net is exactly gospel.

And, isn't one of the Tornado Alley guy's arguments that you can't get one of these engines into detonation by leaning? Maybe I read that wrong......but I don't believe in any case.

But again, we've been running these things using these "dangerous" leaning protocols for millions of flight hours......

Before someone argues that's the reason Continentals have had so many cylinder failures, I'd point out that a lot of those were REALLY old, refurbished cylinders, with a lot of hours. Hence the reason that Lycoming never re-uses cylinders, even on overhauled engines (as opposed to remans), every engine they rebuild gets all new cylinder assemblies. I think that would be what we call a clue.

MTV

mtv wrote:Before someone argues that's the reason Continentals have had so many cylinder failures, I'd point out that a lot of those were REALLY old, refurbished cylinders, with a lot of hours. Hence the reason that Lycoming never re-uses cylinders, even on overhauled engines (as opposed to remans), every engine they rebuild gets all new cylinder assemblies. I think that would be what we call a clue.

MTV

Good call