Where are we on EGTs and CHTs?

[AA5Bman]

The conventional wisdom on engine temperatures seems to have fluctuated a bit over the years, with 380* being the gold standard for a long time as pushed (I think) by the Savvy, GAMI, LOP crowd, which I have generally subscribed to. But then it seemed that 400* might be fine as long as you were sufficiently rich, and I believe some of the Lycoming engines are marked as high as 450* (don’t quote me on this).

The question comes up because I’m kinda-sorta kicking around the idea of finally buying my bucket-list aircraft, a turbo’ed Cessna 206 (continental TSIO-520). I went to look at one recently and it had a fresh (100hr) engine, and it ran hot (at least to me): 400-405* consistently through all phases of flight, even cruise. This kind of freaked me out and I’m curious what you all think about this. I know and have been warned that turbocharged engines run hotter, but what is acceptable? This plane was flown by a mechanic also so he would theoretically know, and it didn’t bother him at all, saying that an NA engine running that hot would be doing so because it was substantially too lean. A turbo’ed engine could run that hot and still be safely rich or LOP, just because turbo’ed engines produce more heat. One is at risk of detonation, one is not. At least this was the logic.

So… not to rip open a whole new EGT/CHT/LOP/ROP debate, but what is the current thinking on temps? And does anyone have any experience with what is normal for a TSIO-520?

 

[TCABM]

While not directly answering your question, I asked some foundational questions around turbos earlier this year and got some good information. Likely worth perusing if you’re considering one.

Thread 'Turbos…I Want To Learn More' https://www.pilotsofamerica.com/community/threads/turbos…i-want-to-learn-more.147689/

My take away is knowing why you want/need the turbo because the juice may not be worth the squeeze because your all around costs are going to increase.

 

[Ed Haywood]

The conventional wisdom on engine temperatures seems to have fluctuated a bit over the years, with 380* being the gold standard for a long time as pushed (I think) by the Savvy, GAMI, LOP crowd, which I have generally subscribed to. But then it seemed that 400* might be fine as long as you were sufficiently rich, and I believe some of the Lycoming engines are marked as high as 450* (don’t quote me on this).

The question comes up because I’m kinda-sorta kicking around the idea of finally buying my bucket-list aircraft, a turbo’ed Cessna 206 (continental TSIO-520). I went to look at one recently and it had a fresh (100hr) engine, and it ran hot (at least to me): 400-405* consistently through all phases of flight, even cruise. This kind of freaked me out and I’m curious what you all think about this. I know and have been warned that turbocharged engines run hotter, but what is acceptable? This plane was flown by a mechanic also so he would theoretically know, and it didn’t bother him at all, saying that an NA engine running that hot would be doing so because it was substantially too lean. A turbo’ed engine could run that hot and still be safely rich or LOP, just because turbo’ed engines produce more heat. One is at risk of detonation, one is not. At least this was the logic.

So… not to rip open a whole new EGT/CHT/LOP/ROP debate, but what is the current thinking on temps? And does anyone have any experience with what is normal for a TSIO-520?

Lycoming publishes a maximum CHT limit for each model in the Operators Manual for that model. Lycoming also recommends keeping CHT below a certain limit for maximum service life.

For example, the IO-360 max CHT is 450, but Lycoming recommends under 400 for continuous operation.

 

[douglas393]

The question comes up because I’m kinda-sorta kicking around the idea of finally buying my bucket-list aircraft, a turbo’ed Cessna 206 (continental TSIO-520). I went to look at one recently and it had a fresh (100hr) engine, and it ran hot (at least to me): 400-405* consistently through all phases of flight, even cruise. This kind of freaked me out and I’m curious

That is what my 2009 T206H does if you are not on topm of it. In my T182T flew to max TIT and CHT were reliably in the 360brange. Do that in my 206 and CHT is 400 to 405. So I fly to keep the CHT to 380. Requires more fuel, and opening the cowl. My mechanic says I am being over cautious but then again he makes money if I have to replace a jug or two. Maybe I am fooling myself but it seems to work and a pilot I know who had more time in turbo 182s felt it was a sound idea. Watching the engine parameters is part of my scan anyhow.

 

[William Pete Hodges]

>>>"saying that an NA engine running that hot would be doing so because it was substantially too lean. ">>>

IMHO if that statement were to end with the words "while running Rich of Peak " it would be accurate. But without those words it is inaccurate. As long as the engine will run smoothly Lean of Peak, AND it is running in the best economy window, THEN the CHTs will be cooler than they would on the rich side of peak EGT. However, not all engines will run smoothly LOP and it is best to verify that capability at loads below 60% for engine safety. I also agree that 380F CHT is better for engine longevity than 405F, but I don't know if 405F is too high for your engine. I keep my IO-360 Lycoming below 360F in cruise.

 

[AA5Bman]

@TCABM good thread recommendation. The John Deacon articles on “those fire breathing turbos” informs most of my knowledge, and they are excellent. I hope they’re still up somewhere.

@William Pete Hodges Yes, I agree.

I guess what I’m *not* hearing is anyone agreeing that a consistent 400* is okay, which is consistent with my long-running understanding.