IO-550G CHTs

[MJHarm]

All,

I’m finally getting back to aircraft ownership after a long hiatus. Previously owned a ‘68 G. I recently test flew an Ovation and was surprised at the high CHTs throughout the flight. It was a summer morning flight in the SouthEast but the temps were approaching 500. 
What should I expect to see?

[Niko182]

8 minutes ago, MJHarm said:

All,

I’m finally getting back to aircraft ownership after a long hiatus. Previously owned a ‘68 G. I recently test flew an Ovation and was surprised at the high CHTs throughout the flight. It was a summer morning flight in the SouthEast but the temps were approaching 500. 
What should I expect to see?

You should not expect to see anywhere near that. Improperly timed mag, old baffles, too low of a fuel flow on climb out, old inaccurate probes, or a combination of it all or the old JPI . I'd guess combination of some of those. I see 390 in the climb out sometimes but rarely, if I'm climbing at a lower IAS to climb faster and its hot outside. The worst I've ever seen was 410 for about a moment leaving Palm Springs in the middle of summer when it was 118 degrees outside. I climbed at a lower IAS because I just wanted to get high out of the heat and was willing to let the CHT get a little hotter because of how hot it was in the cabin. You should not ever see 500 in a continental. I'm fairly certain 460 is the max for continental, and anything higher has the chance of causing damage to the aircraft. Which plane was this if you don't mind me asking?

[MJHarm]

Thanks. Good info. Sure, N46BA.  Intently in Trace-A-Plane.  Any inside info would be appreciated. 

[Fly Boomer]

34 minutes ago, MJHarm said:

temps were approaching 500. 
What should I expect to see?

With those temps, that airplane can expect to see a top overhaul in the very near future.  No idea what the POH says, but Mike Busch says 380 for decent cylinder life.  

[NickG]

3 hours ago, MJHarm said:

All,

I’m finally getting back to aircraft ownership after a long hiatus. Previously owned a ‘68 G. I recently test flew an Ovation and was surprised at the high CHTs throughout the flight. It was a summer morning flight in the SouthEast but the temps were approaching 500. 
What should I expect to see?

Ouch. You'll be burning through cylinders at an extreme rate! I live and fly in Las Vegas where it's usually super-hot. I rarely get CHT's above 390. Sometimes 400-410 in a climb until I drop the nose a bit. Also, I fly LOP at cruise. Something is wrong with either your fuel flow, baffling, and sensors. That is not right and should be setting off alarm bells if you're looking to buy that bird.

[midlifeflyer]

My experience is similar to @Niko182’s. In fact, my friend’s Ovation, which I fly, runs exceptionally cool. I wonder whether it’s a baffle issue?

[MJHarm]

Thanks everyone. We lowered the nose and reduced power to keep things reasonable. We’ll take a close look at the exhaust valves and baffling at pre buy.


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[Schllc]

Something is very wrong with that plane, and 500deg cht’s on a io-550 isn’t just high, it’s dangerous. 
I can’t believe the owner would fly it this way.