Someone on another forum wrote this which I found interesting. Is this pretty much your take on things?
"The IO-520s being operated by ham fisted aviators have given big Continentals a bit of a bad rap. One of the problems with the IO 520 is that takeoff rpm is 2850, and that's putting a lot of stress on those engines.
I know of operators in AK who operate IO 520s day in and day out, and take them to TBO all the time, often without changing a cylinder. The O-470 engines are bullet proof as any 180/182/Bonanza owner will tell you. TBO isnt' quite as high as Lycoming, but.....prices aren't either.
I once had a very similar discussion with a Lycoming tech rep, and his response was that he was pretty confident that Continentals are just as reliable in almost ever regard as Lycomings, all in all.
The big hoo haw over crankshafts in the big Continentals a while back?? Guess what--Lycoming uses the same supplier of crankshaft blanks, and had the same issue...They were just lucky enough to catch every one of the engines they built with those cranks before they were delivered to customers and fixed them. Quietly.
If you're going to run a 520 as a carbureted engine, you'll be running MUCH lower rpm at takeoff, like 2700, and I'd bet you'll find that engine will easily run reliably to 2000 hours.
But remember--the single biggest killer of engines is non-use. Let that thing sit in a hangar, fly it ten hours a year, and good luck.
As to shock cooling being responsible for cracking cylinders, I've been told by a couple of good engine experts that this is mostly a fairy tale, and when it DOES happen, or appears to happen, it's associated with engines that have cylinders that are VERY old, work hardened, and should have been trashed decades ago. I've seen Continental cylinders that were multiple runs, and literally decades old. This is specifically why Lycoming will not salvage ANY cylinder that comes into their plant for rebuild.
I'm not suggesting you should close the throttle in cold temps, and run it at idle in a rapid 4000 foot descent....you do have to apply a little common sense, after all.
Cylinders are tapered toward the tops. As the engine heats up, the head and top of the cylinder "grows" a bit due to heat. Pull the power off, and descend a long ways in cold air and you can change the choke of the cylinder.
BUT, the biggest issue with running long, idle power descents is that the propeller is now driving the engine, as opposed to the other way around, and THAT isn't real good for the engine. However, even that won't crack cylinders."
"The IO-520s being operated by ham fisted aviators have given big Continentals a bit of a bad rap. One of the problems with the IO 520 is that takeoff rpm is 2850, and that's putting a lot of stress on those engines.
I know of operators in AK who operate IO 520s day in and day out, and take them to TBO all the time, often without changing a cylinder. The O-470 engines are bullet proof as any 180/182/Bonanza owner will tell you. TBO isnt' quite as high as Lycoming, but.....prices aren't either.
I once had a very similar discussion with a Lycoming tech rep, and his response was that he was pretty confident that Continentals are just as reliable in almost ever regard as Lycomings, all in all.
The big hoo haw over crankshafts in the big Continentals a while back?? Guess what--Lycoming uses the same supplier of crankshaft blanks, and had the same issue...They were just lucky enough to catch every one of the engines they built with those cranks before they were delivered to customers and fixed them. Quietly.
If you're going to run a 520 as a carbureted engine, you'll be running MUCH lower rpm at takeoff, like 2700, and I'd bet you'll find that engine will easily run reliably to 2000 hours.
But remember--the single biggest killer of engines is non-use. Let that thing sit in a hangar, fly it ten hours a year, and good luck.
As to shock cooling being responsible for cracking cylinders, I've been told by a couple of good engine experts that this is mostly a fairy tale, and when it DOES happen, or appears to happen, it's associated with engines that have cylinders that are VERY old, work hardened, and should have been trashed decades ago. I've seen Continental cylinders that were multiple runs, and literally decades old. This is specifically why Lycoming will not salvage ANY cylinder that comes into their plant for rebuild.
I'm not suggesting you should close the throttle in cold temps, and run it at idle in a rapid 4000 foot descent....you do have to apply a little common sense, after all.
Cylinders are tapered toward the tops. As the engine heats up, the head and top of the cylinder "grows" a bit due to heat. Pull the power off, and descend a long ways in cold air and you can change the choke of the cylinder.
BUT, the biggest issue with running long, idle power descents is that the propeller is now driving the engine, as opposed to the other way around, and THAT isn't real good for the engine. However, even that won't crack cylinders."
