This article is very relevant:
The type of engine dictates how many hours it will run
Well, yes, sure, it’s already been well covered that almost no turbo Lyco/Conti has made 1k hrs without needing some or all new cylinders.
But the common “not highly tuned” stuff should go way beyond TBO. So not the “IO540” in some aerobatic competition plane which, despite not being turbo, has 10.5:1 pistons. I was told by an experienced US engine shop that an 8.5:1 IO540 will go way beyond TBO, and only if you go to 9.5:1 or higher (which improves SFC considerably, but isn’t legal for a certified engine) does this affect things.
From
Bulletproof Engines
Against this backdrop of reduced flight hours and dwindling owner maintenance, can any one engine really rise above the rest as best of the best? Indeed it can and according to our shops, that engine is the Lycoming IO-360-L2A, the 180-HP parallel valve four-cylinder used in the restart Cessna 172s since 1997. The parallel-valve 360s have always been robust engines because they have strong cases and cylinders that aren’t expected to deliver high horsepower.
Although the basis of this engine has been around for years, it seems to have hit the sweet spot in the new 172s.
“It’s a 180-HP engine, it’s de-rated and I’ve had them come in here with 4000 hours on them,” says Dave Allen of Poplar Grove Airmotive, near Rockford, Illinois.
“American Flyers runs them for 4000 hours, they put cylinders on at 2000 and a fuel servo and run them another 2000 hours. I haven’t seen anything else do that,” he adds.
To be honest, however, a lot of engines would go beynd 2000hrs if you chuck away the whole top at 2000hrs 
So that article is a bit disingenuous. It’s a bit like the famous Monty Python video about “what have the Romans done for us” or our version of it what has EASA done for us
There is going to be a lot of correlation between long life and type of usage. If an engine is popular in the US flying school scene, you will see this. When I was doing my IR in Arizona, they were doing 700+ hrs a year, refuelling at night… a very smooth operation. Zero corrosion issues, too.
Well, yes, sure, it’s already been well covered that almost no turbo Lyco/Conti has made 1k hrs without needing some or all new cylinders. But the common “not highly tuned” stuff should go way beyond TBO. So not the “IO540” in some aerobatic competition plane which, despite not being turbo, has 10.5:1 pistons. I was told by an experienced US engine shop that an 8.5:1 IO540 will go way beyond TBO, and only if you go to 9.5:1 or higher (which improves SFC considerably, but isn’t legal for a certified engine) does this affect things.
As I mentioned, I am not aware of turbo making 1000h before needing “something” (other than TSIO360 Raven Seneca left engine mentioned above)
Good point on compression ratio maybe the reason why turbo Rotax live longer (also because of lower power outputs)
The only thing better than the Lycoming IO-360 is the Lycoming HIO-360. The helicopter engine is made with some very expensive beefed-up parts. The guys in the engine shops were telling me about the differences. I really like the 360 and feel very safe flying on top of, or behind one.
The helicopter engine mods for the 0-360 sound interesting. Isn’t that engine installation fan cooled? Cooling becomes the issue after you find a way to increase power (in this case with more RPM IIRC) and proportionately increase mechanical strength. A local Reno racer is up to over 800 HP from a turbo Lycoming originally designed for 350 HP but it requires lots and lots of ADI.
Calendar time between overhauls is equally interesting given that few of us fly enough to wear out an engine in 12 years. I think a calendar time record for an engine for an aircraft engine still in service without major work might be this A65 Original cylinders were rebored only a short time ago at 1500 hrs, but the bottom end is still original, never overhauled since new in 1945. My O-320’s 52 years without any disassembly (since new) pales in comparison.
The only thing better than the Lycoming IO-360 is the Lycoming HIO-360. The helicopter engine is made with some very expensive beefed-up parts
Can you run helicopters airframes & engines past their 10kh & 2kh TBD? (To Be Dead )
Peter wrote:
In the right conditions, most engines would reach 3-4k hrs, but they would be shagged by then and the overhaul will cost a fair bit more. Which doesn’t matter if it is a flying school.
Of course you shouldn’t generalise from single experiences, but our IO-360-L2A, which was operated in a club environment and overhauled after 3400 hours was in good condition at the time of overhaul. We specifically asked the shop (Nicolson-McLaren) about that. There were also very few surprises at the overhaul. No more than about £1000 worth if memory serves. And that was a non-derated 180 hp installation in a Cessna 172S.
Interesting comments about the use of unleaded fuels and how it may have lasted longer if such fuels were used.
And yet on a daily bases I see people putting in 100LL when UL91 is not only the more suitable fuel but is also cheaper.
“And yet on a daily bases I see people putting in 100LL when UL91 is not only the more suitable fuel but is also cheaper.”
If only it was also more available.
