oil temperature and cylinder head temperature questions

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Masterius
Senior Airman
Posts: 216
Joined: 30 May 2019, 14:36

oil temperature and cylinder head temperature questions

Post by Masterius »

This is what I've gleaned from reading and research:

Oil Temperature
Desired: 70C
Maximum: 88C
Minimum: 60C

Cylinder-Head Temperature
Desired: 170C
Maximum: 232C
Minimum: 125C

With regards to the oil temperature, I've yet to see any practical way of controlling that. Winter, Spring, Summer, and Fall, oil temperature reaches 86-88 degrees and stays there. Makes me a bit concerned, since that's pegged towards the maximum.

With regards to CHT, if I let my copilot control that, he'll maintain it around 215C. Granted, that's still 17 under the max, but, then again, it's also 45 over the desired.

Just curious about the differences between actual desired and sim desired temperatures, and does it really matter as long as the minimums and maximums aren't exceeded?

Chevalier
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TreeTops
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Joined: 07 Apr 2010, 06:13

Re: oil temperature and cylinder head temperature questions

Post by TreeTops »

I am not qualified to speak with respect to engine targets. There are others who can perhaps fill that role for you.
However, the CHT is controlled by the cowl flaps. If you wish to run cooler then you will have to take control of them.
I never use the FE but perhaps the method you could use is to get to cruise and then take over the cowl flaps, open them up as desired, and then reassign them to the FE for the descent and landing.
Something to consider though, is the more you open the flaps the more drag and thus slower the plane will fly. So its a trade off between CHT temperature and airspeed.
Cheers
Trev

boris4356
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Posts: 384
Joined: 26 Sep 2009, 20:42
Location: Canada

Re: oil temperature and cylinder head temperature questions

Post by boris4356 »

Masterius wrote: 04 May 2021, 23:42 This is what I've gleaned from reading and research:

Oil Temperature
Desired: 70C
Maximum: 88C
Minimum: 60C

Cylinder-Head Temperature
Desired: 170C
Maximum: 232C
Minimum: 125C

With regards to the oil temperature, I've yet to see any practical way of controlling that. Winter, Spring, Summer, and Fall, oil temperature reaches 86-88 degrees and stays there. Makes me a bit concerned, since that's pegged towards the maximum.

With regards to CHT, if I let my copilot control that, he'll maintain it around 215C. Granted, that's still 17 under the max, but, then again, it's also 45 over the desired.

Just curious about the differences between actual desired and sim desired temperatures, and does it really matter as long as the minimums and maximums aren't exceeded?

Chevalier
Hi Al,

I don't think the higher numbers really make much difference in the sim. I let my co-pilot manage everything and I usually average 600-800 hours per engine. I have come close to 1000 hours the odd time, but not that often. The definitive conclusion would be how many hours should you have gotten from an engine in real life, but i can't answer that. Maybe Alan can shed some light on this.

Bill

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Masterius
Senior Airman
Posts: 216
Joined: 30 May 2019, 14:36

Re: oil temperature and cylinder head temperature questions

Post by Masterius »

TreeTops wrote: 05 May 2021, 03:08 However, the CHT is controlled by the cowl flaps. If you wish to run cooler then you will have to take control of them.
Actually, I'm full manual with cowl flaps, RPM, and intercoolers. I appreciate the tips and suggestions, however!

It's because I'm full manual that I wanted to verify what temps the CHT should run. I don't want to harm the engines by running too low based on the "desired" 170C if that's actually not how the engines are modeled. I'm going to experiment later today by running them that low, and see how much lower the oil temperature drops...if any.

Thanks again!

Chevalier
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Masterius
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Posts: 216
Joined: 30 May 2019, 14:36

Re: oil temperature and cylinder head temperature questions

Post by Masterius »

So...flew last night from LAX to Salt lake City, climbing to 29,000 feet and cruising there. During the climb, with cowl flaps at around 80-85% open, I could get the CHT around 170C. Once at altitude, and with cowl flaps at 12%--give or take--I could easily maintain a CHT of 170C. At that temperature, the oil temps now ranged around 75-78C...much closer to the desired 70C, and substantially lower than the usual 85-88C they've been running.

We'll see what long-term operations at those temps do.

Chevalier
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