GAHorn wrote:(OK...being troublesome here now..but the virus is adding to boredom...). Soo... I have to buy his book to understand what we already know?
Clearly you didn't know that blow-by increases temperatures and hot spots and adds to problems within the cylinders.
GAHorn wrote:It’s my opinion the differences of heat dissipation and expansion-rates between aluminum and steel is the root cause for this failure .... blow by is a red herring.
You can lead a horse to water, but it's still a horse. Blow-by increases hot spots. Hot spots, increases out of round conditions. Out of round conditions are problematic at the head/cylinder junction and any sealing. That's engine 101 and not unique to aircraft engines.
GAHorn wrote: And it stands to reason these differences will be more exaggerated in large bores than in small bores... probably the major reason small bore engines suffer this failure less frequently than the big bores.
Perhaps. Irrelevant to original post and question.
GAHorn wrote: (If blow-by is a problem due to improper break-in and cylinder-glazing we’d fix that early in the engine’s life, right? I mean, who wants to keep low compressions and high oil consumption? Is it being suggested by Mr. Busch that since we discovered we had blow-by that we should discard those heat-damaged new cylinders and start over? I think not. Most, if not all operators would de-glaze them and go thru break-in again. Does that mean we will have some head blow off in the future because of latent damage caused by that blow by?)
OK, this is a strawman argument. Nobody claimed anything about what should be done. However, if you read the book, you'd learn nothing new as Mr. Busch does indeed recommend deglazing and re-ringing rather than replacing where appropriate.
It's also a red herring argument as it's got nothing to do with the original post.
GAHorn wrote:Even if the imagined Or real intricacies of blow-by inside a cylinder contributes to the problem, it cannot be managed by any tool or gauge we have in the cockpit (except perhaps by closing the throttle, which is exactly what I did when my IO-520 #4 cyl blew it’s top on takeoff.) I doubt there is any information in his book that would have prevented that failure. (We know how he makes his money.)
Another strawman. Your obsession with blow-by is problematic in our discussion and in the original post.
GAHorn wrote:Technicalities are fun and entertaining, but I don’t have to know how to alloy brass to make a gear to build a clock just to know what time it is.
GAHorn wrote:If you have read his book, what Busch-recommended operational changes have you undertaken to avoid this particular problem?
Run cooler than the book recommends.
GAHorn wrote:... and how can you quantify that those changes, if any, have resulted in fewer cylinder-head failures for you?
Or did we simply go out and buy some expensive monitoring equipment he promoted so as to feel better about things?
I've done nothing other than try to keep my cyl head temps lower. I do not have a full EMS, but when I upgrade to an O360, I will likely install one at that time. Further, it is all but impossible to prove something that doesn't happen, but I will defer to Mr. Busch's thousands of hours of EMS data. You do you.
GAHorn wrote:(Boy, I must have gotten up on the wrong side of the bed...)
I think you do that most days on here.
That's all fine, really, but the original poster asked for a recommendation for an alarm on his EMS. You made a recommendation of 250-450 for the green arc because yours runs at 350. You based this on what data precisely? Mike Busch, on the other hand, runs a company that analyzes engine data from thousands of planes with thousands of hours of data and monitors trends on a variety of factors - based on all of this, he recommends 380 as an alarm point. It seems you've latched onto this blow-by comment by Busch, and because you don't "buy into it", you have dismissed his entire argument based on a single data point when you have nothing but anecdotal evidence to contradict.
Now, that doesn't mean you're wrong, merely that attacking Busch and dismissing a recommendation based on a single comment you disagree with sounds a lot like grandstanding when he has reams of data to back up his position. His, like yours, is a recommendation - the difference is, this is what he does for a living; monitor engines for customers.
At the end of the day, you don't have to read his book, you don't have to take his recommendation, you don't even have to agree with anything that's posted on here (you often don't), but just because you don't understand how blow-by increases temps and hot spots leading to out of round conditions on cylinders and exacerbating issues related to those cylinders and specifically the cylinder/head junction doesn't make him wrong or you right...just more of what you usually are.