What is optimal operating temperature?

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The_Captain

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What do you consider optimal operating temperature an engine needs to reach to ensure moisture burn off? How long does the engine need to stay at that temperature to remove moisture? It takes my pentastar a while to get to an oil temp of 174 degrees. If I sit in a drive-thru or a traffic back up it will hit 190°. My commute is only 12 to 14 miles and the temperature rarely reaches the 170's mostly gets to the high 160's.
 
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Vapor pressure will remove moisture at very low temps. But higher temps are faster. So duration at temp is the question.

150 is fine with me as long as excessive fuel and moisture are not present, 170 is actually a pretty nice compromise...
 
Originally Posted By: SteveSRT8
Vapor pressure will remove moisture at very low temps.


exactly, Many will argue that you need to hit the boiling point of water but that's not necessary.
 
Where does the majority of vapor escape? Ultimately the exhaust??

I'm just imagining the various routes and locations for it to condense before getting out. Say in a less than fully warmed up engine.
 
Originally Posted By: Jiblet
Where does the majority of vapor escape? Ultimately the exhaust??

I'm just imagining the various routes and locations for it to condense before getting out. Say in a less than fully warmed up engine.


PCV is what ventilates the crankcase...
 
Originally Posted By: Sawdusted
If you're driving 12-14 miles and your car is not up to operating temp, I suspect your thermostat could be stuck open.


Please note he was concerned about OIL temp, not coolant. They can be quite different depending on the engine design and power density...
 
Originally Posted By: Jiblet
Where does the majority of vapor escape? Ultimately the exhaust??

I'm just imagining the various routes and locations for it to condense before getting out. Say in a less than fully warmed up engine.


PCV extracts the vapors from the crankcase and replaces them with fresh air. The extracted vapors go to the intake, which yes... eventually leads to the exhaust :)
 
Originally Posted By: The_Captain
What do you consider optimal operating temperature an engine needs to reach to ensure moisture burn off? How long does the engine need to stay at that temperature to remove moisture? It takes my pentastar a while to get to an oil temp of 174 degrees. If I sit in a drive-thru or a traffic back up it will hit 190°. My commute is only 12 to 14 miles and the temperature rarely reaches the 170's mostly gets to the high 160's.

Your experience is not atypical even in a mild SC winter.
I'm not entirely familiar with your Jeep but it sound like it's not equipped with a heat exchanger and has an exposed sump.
If that is the case, installing a shroud over the sump to block air flow could assist in generating higher oil temp's and retaining it in the oil.
For long engine life you do want to get your oil temp's up at least to 174F most times you drive your car if possible.
 
Hi,
The_Captain - This is one perspective to your question about "optimal engine temperature". Moisture itself evaporates early in the warm up process but its handling is another matter, see below

Firstly it depends on the engine family and its structure. Some engines are designed to reach their optimum cooling system temperature quickly, stabilising the coolant/oil temperature may take up to 20 minutes or so depending on use and ambient etc. Even engines within one family may "breath" differently from another depending on the application

The condition of the engine plays a role especially cooling system thermostat, PCV etc.

These figures give you a guide;

Optimum oil temp typically is above 80C 176F and in a range up to 90C 194F

One engine family I'm very familiar with had these parameters;
Normal 110C 230F
Warning 115 239F
Shut down 120C 248F

My Averages over all engines within the family was 103C 217F

My Porsche 928S4's average oil temp was 86C 187F - this engine has a thermo controlled oil cooler and thermo controlled air flow intake flaps.
Even in the Tropics where I live this engines typically took around 20-25mins to reach a stabilised oil/coolant temperature relationship

I hope this is of interest
 
Originally Posted By: Doug Hillary

My Porsche 928S4's average oil temp was 86C 187F - this engine has a thermo controlled oil cooler and thermo controlled air flow intake flaps.
Even in the Tropics where I live this engines typically took around 20-25mins to reach a stabilised oil/coolant temperature relationship
I hope this is of interest

And the 9 litre sump doesn't help especially in the cool fall and spring months. I no longer drive mine in the winter any longer particularly this year as we're having a real classic Canadian winter with the daily high staying well below freezing and a ton of snow.
 
Somewhere on the net is a graph from ford that shows engine wear vs engine temp. It shows less wear as the engine runs hotter. Around 200-210 is optimal.160-180 show more wear.
 
Originally Posted By: Chris142
Somewhere on the net is a graph from ford that shows engine wear vs engine temp. It shows less wear as the engine runs hotter. Around 200-210 is optimal.160-180 show more wear.


I'm new here, but been around the block a few times. I had this in my reference files.

 
The pentastar does have an oil cooler. The water temp usually runs between 200° to 215°. The oil temp will get up to 185° to 190° when I am driving around town or going down the highway. My daily commute is the majority of my drive time Monday through Friday.I am sure that a traffic jam, hard driving or a really long idle time would cause it to go above the average temps.
 
Originally Posted By: flaokie
Originally Posted By: Chris142
Somewhere on the net is a graph from ford that shows engine wear vs engine temp. It shows less wear as the engine runs hotter. Around 200-210 is optimal.160-180 show more wear.


I'm new here, but been around the block a few times. I had this in my reference files.




Welcome to the forum! Nice post.
 
Originally Posted By: Chris142
Somewhere on the net is a graph from ford that shows engine wear vs engine temp. It shows less wear as the engine runs hotter. Around 200-210 is optimal.160-180 show more wear.


This was published in HP Books in the 60's. It is very old data and was a study of COOLANT temperature.

It may not even be valid anymore as oils and engines are quite different these days.
 
Originally Posted By: SteveSRT8

This was published in HP Books in the 60's. It is very old data and was a study of COOLANT temperature.

It may not even be valid anymore as oils and engines are quite different these days.


The graph is labeled engine life vs oil temperature. It doesn't make sense either way as cold coolant temp or cold oil will lead to more wear.
 
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