spec that measures ability of oil to cool an engin

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Here is some some data from Heywood's book
on "Internal Combustion Engines" with regard to the energy splits:

He starts with 100% fuel power (Energy/time)
and split the figures up. Here is the SI engine
data:

Brake - 27% (power to road)
Cooling - 25%
Oil - 14%
Exhaust 30%

Diesel:
Brake - 35%
Cooling - 28%
Oil - 8%
Exhaust - 27%

The other 3% is split up as follows:
2% for convection cooling (air past engine)
1% radiative cooling.
 
Originally Posted By: MolaKule
Here is some some data from Heywood's book
on "Internal Combustion Engines" with regard to the energy splits:

He starts with 100% fuel power (Energy/time)
and split the figures up. Here is the SI engine
data:

Brake - 27% (power to road)
Cooling - 25%
Oil - 14%
Exhaust 30%

Diesel:
Brake - 35%
Cooling - 28%
Oil - 8%
Exhaust - 27%

The other 3% is split up as follows:
2% for convection cooling (air past engine)
1% radiative cooling.


Molakule,
another data point, albiet not as well researched as Heywood (my fave book).

http://www.formula1-dictionary.net/lubricants.html

Quote:
In a Formula 1 engine running at full power, friction induced by the movement of moving parts absorbs up to 40% of the mechanical energy produced by the combustion of the fuel. The phenomena involved are for example the rubbing of the pistons and piston rings on the cylinder wall, the connecting rods on the bearing shells, the crankshaft on its journals, and the camshaft (opening and closing the valves).


So for the 800hp example given, 1300 hp are actually generated by the engine, of which 500 odd are lost through frictional processes, largely heating oil, (with at least the piston/bore friction heading largely to the coolant rather than the sump).

It's very close same ballpark as Heywood's number.
 
Nice link, Shannow. As an aside, the author needs to make some updates or corrections at the bottom chart. Total, Mobil, and Shell still are lubricant and fuel partners, and never stopped in recent memory. Esso is still on McLaren stuff, along with the Mobil 1 logo.
 
Originally Posted By: Shannow
So for the 800hp example given, 1300 hp are actually generated by the engine, of which 500 odd are lost through frictional processes, largely heating oil, (with at least the piston/bore friction heading largely to the coolant rather than the sump).


I have seen similar numbers before and that has always surprised me, at least at some intuitive level. I mean I know details from my ME classes (and I know how much heat is rejected at the radiator) but it's a lot of heat not doing any work.
 
Originally Posted By: MolaKule
Here is some some data from Heywood's book
on "Internal Combustion Engines" with regard to the energy splits:
He starts with 100% fuel power (Energy/time) and split the figures up.
Here is the SI engine data:
Brake - 27% (power to road)
Cooling - 25%
Oil - 14%
Exhaust 30%

Diesel:
Brake - 35%
Cooling - 28%
Oil - 8%
Exhaust - 27%


The other 3% is split up as follows:
2% for convection cooling (air past engine)
1% radiative cooling.


+1


Originally Posted By: Garak
Originally Posted By: zeng
Quote:
........ about 60 percent of the engine cooling is handled by the radiator and coolant, the other 40 percent (more in an air-cooled engine) must be taken care of by the engine oil.

http://www.gregraven.org/hotwater/oil/

That doesn't give any reference to that claim.


As I understand it, by engine cooling the author refers to the sum of (coolant) cooling and oil (cooling) in Mola's quote above,and Greg Raven was quite spot on... in gasoline engine.
This engine cooling energy, in combination with the other brake (horse power energy) and exhaust (waste energy) etc constitutue total energy of fuels in use.
 
Originally Posted By: kschachn
Originally Posted By: Shannow
So for the 800hp example given, 1300 hp are actually generated by the engine, of which 500 odd are lost through frictional processes, largely heating oil, (with at least the piston/bore friction heading largely to the coolant rather than the sump).


I have seen similar numbers before and that has always surprised me, at least at some intuitive level. I mean I know details from my ME classes (and I know how much heat is rejected at the radiator) but it's a lot of heat not doing any work.


For sure, which is why our lab and others are doing R&D on Ionic Friction Modifiers with anti-wear capabilities.

http://www.bobistheoilguy.com/forums/ubbthreads.php/topics/3941560/Headaches,_Aches,_Pain's,_and_#Post3941560

http://www.bobistheoilguy.com/forums/ubb...n_g#Post3442516
 
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Originally Posted By: zeng
This engine cooling energy, in combination with the other brake (horse power energy) and exhaust (waste energy) etc constitutue total energy of fuels in use.

Yes, they do, but that doesn't exactly tell the whole picture of how it's dissipated. Oil cooling circuits complicate the matter.

As was already indicated, if one really wishes to be picky, all engines are cooled predominantly by air, since the air is what carries the heat away from a radiator.
 
In the head/cylinder system, the heat of combustion is transferred externally via direct conduction and inside the cylinder, through conduction by the oil film.

The thermal energy conducted to the head is transferred by the coolant fluid (forced convection cooling) and the oil transfers its thermal energy to the cylinder block, where again, coolant fluid
carries most of that thermal energy away. So we have conduction then forced convection.

As Garak stated, most of the thermal energy is transferred via forced convection, first by liquid cooling and then by air cooling.

In air-cooled engines the heat of combustion is conducted to the head and to the oil, where through forced convection the head carries the thermal energy to the environment.
 
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Originally Posted By: Garak
Originally Posted By: zeng
This engine cooling energy, in combination with the other brake (horse power energy) and exhaust (waste energy) etc constitutue total energy of fuels in use.

Yes, they do, but that doesn't exactly tell the whole picture of how it's dissipated. Oil cooling circuits complicate the matter.

As was already indicated, if one really wishes to be picky, all engines are cooled predominantly by air, since the air is what carries the heat away from a radiator.


Agreed.
Don't forget ... there is engine cooling by direct radiation as well, over and above engine cooling by conduction and convection described above, which at the end of the day still passes through indirect radiation eventually ..... to surrounding air ... as a result of tempeature differentials.
blush.gif
 
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Originally Posted By: MolaKule
Originally Posted By: camrydriver111
I was asking about the term "thermodynamic solution".


I see now what you are saying, and I thought everyone would remember the solutions to a set of simple thermo equations I had done in the past, a "Back of the Napkin" thingy. I mean, it was only 14 years ago.
lol.gif



Oh, you mean thermodynamic equations!

The word solution makes it sounds like the chemistry definition of a solution, which makes it confusing to readers.
 
Originally Posted By: zeng
Don't forget ... there is engine cooling by direct radiation as well, over and above engine cooling by conduction and convection described above, which at the end of the day still passes through indirect radiation eventually ..... to surrounding air ... as a result of tempeature differentials.
blush.gif


Certainly, but I'd expect cooling by true radiation of the heat to be substantially lower than what is stripped off by the coolant being cooled by the air. As an aside, I'd probably be more comfortable running a sump half empty (assuming that the pickup is still submerged at all times) than I would be running a cooling system half empty.
wink.gif
 
Originally Posted By: bobbydavro
http://papers.sae.org/2009-01-2744/

Preview has a heat map to give an indication of energy


Found this pertinent to other discussion topics....

Quote:
The proportions of heat rejected to the different primary paths (i.e. brake, cooant, oil, charge cooler, exhaust and external) were found to vary with engine speed and load. Also, friction power was found to vary principally as a function of engine speed with some small dependency on engine load.


A toyota paper of all things
http://papers.sae.org/952550/

Quote:
Temperature distributions on the surface of the connecting Rod big end bearing were measured to understand the margin to the allowable limiting temperature. The results show that the temperature difference between the bearing surface and the feed oil is independent of the engine load, but quadratically increased with the enignes speed, and that the bearing surface temperature on the rod side is higher than those on the cap side.


Again, (and not arguing with you bobbydavro) not discounting the contribution of oil to removing heat from the engine (and you are correct, it's all to air)...dipstick location in my caprice is 15C hotter than the sump surface temperature, so heat transfer is occurring.

I still assert that most of the heat that the oil is removing is due to the oil doing it's job, not "carrying it away" from hot parts.
 
I agree. Internal friction in the oil is massive.

Have seen interesting effects of friction modifiers on heat transfer of parts though. Eg cooler piston temperatures because the oil allows more heat from the piston to liner.

From memory you can get 4C cooler oil running temperatures due to a shift from 10W-60 to 0W-30
 
Originally Posted By: bobbydavro
I agree. Internal friction in the oil is massive.

Have seen interesting effects of friction modifiers on heat transfer of parts though. Eg cooler piston temperatures because the oil allows more heat from the piston to liner.

From memory you can get 4C cooler oil running temperatures due to a shift from 10W-60 to 0W-30


Sounds about right.

Here's an air cooled example, where SAE 30 to SAE 60 increased measured piston temperature by 11C.

My own testing 5W20 to 20W60 in my mower, bulk oil temperature with a thermocouple was similarly about 10C.
 
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