As sump oil temperature rises and the oil thins, is less heat generated in the bearings?
GM recommends Mobil 1 15w50 for 2016 Corvette
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So 15w50 instead of 5w30 in a Corvette should heat up faster and activate the AWs sooner?
edit; Remember we won't see redundant pressure with the active oil pump.
edit; Remember we won't see redundant pressure with the active oil pump.
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Originally Posted By: Garak
Originally Posted By: Shannow
And big end bearing temperatures, and their response to RPM and load at varying RPM...
That's the best graph or chart I've seen on the matter yet.
Yes, it's a good one. Information dense: various loads, various RPM, various starting oil temps (right side number, if I recall correctly), yet all laid out in a clear and easy to read format.
Originally Posted By: Shannow
And big end bearing temperatures, and their response to RPM and load at varying RPM...
That's the best graph or chart I've seen on the matter yet.
Yes, it's a good one. Information dense: various loads, various RPM, various starting oil temps (right side number, if I recall correctly), yet all laid out in a clear and easy to read format.
Originally Posted By: userfriendly
So 15w50 instead of 5w30 in a Corvette should heat up faster and activate the AWs sooner?
edit; Remember we won't see redundant pressure with the active oil pump.
My understanding is that it will heat up quicker, but always be thicker than the 5W30, even if a little warmer. Good point about the AW activation, never though of that angle.
So 15w50 instead of 5w30 in a Corvette should heat up faster and activate the AWs sooner?
edit; Remember we won't see redundant pressure with the active oil pump.
My understanding is that it will heat up quicker, but always be thicker than the 5W30, even if a little warmer. Good point about the AW activation, never though of that angle.
Originally Posted By: userfriendly
So 15w50 instead of 5w30 in a Corvette should heat up faster and activate the AWs sooner?
Yes, and no.
Yes, in that on fresh metal surfaces it's certainly the case. No in that yesterday's tribofilm will last through today's warm-up.
But as explained to me by an ex Castrol guy over dinner, the "start-up" wear is the wear that takes place AS the lube thins, and BEFORE the AW kicks in.
edit, kicked it around in this thread for a bit.
https://bobistheoilguy.com/forums/ubbthr...on.#Post3680194
Mola's "SX-UP" oil additive was designed with multiple activation temperatures.
So 15w50 instead of 5w30 in a Corvette should heat up faster and activate the AWs sooner?
Yes, and no.
Yes, in that on fresh metal surfaces it's certainly the case. No in that yesterday's tribofilm will last through today's warm-up.
But as explained to me by an ex Castrol guy over dinner, the "start-up" wear is the wear that takes place AS the lube thins, and BEFORE the AW kicks in.
edit, kicked it around in this thread for a bit.
https://bobistheoilguy.com/forums/ubbthr...on.#Post3680194
Mola's "SX-UP" oil additive was designed with multiple activation temperatures.
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Originally Posted By: Shannow
OK, here's a comparison of heating rates.
One with constant RPM, and 6 fold load increase, and the other with the same applied torque, and a three fold RPM increase (three times that power).
As you can clearly see, the RPM has a much bigger influence on the power generated in heating the oil than the load (massive fires)....
Exactly what "oil temperature" are they plotting? Unless you can provide the link that talks in detail how those charts were produced, I'm taking the info in the graphs as simply showing the heat generated in the journal bearing itself due to RPM and the heat generated by the physical torque load to the bearing. The physical loads in those graphs could have been produced by an electric motor for that matter. It's not addressing the effect on the oil temperature in the sump of an ICE due to massive heat generated in the combustion chambers and where all that heat goes when putting out 400~600 HP.
Look at the numbers in your example graphs. Curves in the graph on the left is 10 Nm torque (7.3 ft-lbs) at 1000 RPM = 1.4 HP, and 10 Nm (7.3 ft-lbs) at 3000 RPM = 4.2 HP. Curves in the graph on the right is 10 Nm at 2000 RPM = 2.7 HP and 60 Nm (44.3 ft-lbs) at 2000 RPM = 16.9 HP.
All the graphs are focusing on the bearing itself, and showing that there is more heat generated due to the shearing friction in the bearing than due to the physical load going into the bearing. That goes along with what you said back on page 4. I have no problem with that.
Originally Posted By: Shannow
It's more related to RPM than specific engine load, and yes, higher vicsosity with more shear will run hotter naturally, but those two effects never bring it back to the oil film thickness of a thinner oil under the same RPM/Load.
I'm specifically talking about the added heat going into the oil from hotter surfaces inside the engine - specifically the top of the heads, the cylinder bores/liners, the bottom dome area and skirts of the pistons when massive amounts of HP are produced by the engine. That is what happens in the high HP Vette engine when running flat out for long duration on the race track (the subject of this thread). Those internal engine surfaces can increase in temperature well above what the cooling system is running at when you cram lots of fuel & air into a combustion chamber and explode it. The cooling system can't keep every surface inside the engine that comes in contact with the oil to 100 deg C. The surface of the cylinder wall the rings sweep across runs quite a bit hotter than the side of the cylinder wall that's in contact with the coolant.
Oil splashing up under the pistons and on the inside of the cylinder walls is heated up well above what any bearing is going to heat oil up to. A major part of oil function is to provide additional cooling to these surfaces, and by doing so the sump temperature will increase above from just the bearing's influence. That added heat from combustion at high HP levels on top of the heat generated by the bearing rotational RPM contributes to an overall higher sump temperature compared to not putting tons of power out at the same RPM. Goes along with my example of what the stabilized sump temperature difference would be if running the engine at 4000 RPM with a 30 HP load on the crank vs running the same engine running at 4000 RPM with a 300 HP load on the crank. The sump temperature is going to stabilize quite a bit higher under the 300 HP load condition due to the extra heat the oil picks up from hotter internal surfaces - especially if there is no oil cooler.
OK, here's a comparison of heating rates.
One with constant RPM, and 6 fold load increase, and the other with the same applied torque, and a three fold RPM increase (three times that power).
As you can clearly see, the RPM has a much bigger influence on the power generated in heating the oil than the load (massive fires)....
Exactly what "oil temperature" are they plotting? Unless you can provide the link that talks in detail how those charts were produced, I'm taking the info in the graphs as simply showing the heat generated in the journal bearing itself due to RPM and the heat generated by the physical torque load to the bearing. The physical loads in those graphs could have been produced by an electric motor for that matter. It's not addressing the effect on the oil temperature in the sump of an ICE due to massive heat generated in the combustion chambers and where all that heat goes when putting out 400~600 HP.
Look at the numbers in your example graphs. Curves in the graph on the left is 10 Nm torque (7.3 ft-lbs) at 1000 RPM = 1.4 HP, and 10 Nm (7.3 ft-lbs) at 3000 RPM = 4.2 HP. Curves in the graph on the right is 10 Nm at 2000 RPM = 2.7 HP and 60 Nm (44.3 ft-lbs) at 2000 RPM = 16.9 HP.
All the graphs are focusing on the bearing itself, and showing that there is more heat generated due to the shearing friction in the bearing than due to the physical load going into the bearing. That goes along with what you said back on page 4. I have no problem with that.
Originally Posted By: Shannow
It's more related to RPM than specific engine load, and yes, higher vicsosity with more shear will run hotter naturally, but those two effects never bring it back to the oil film thickness of a thinner oil under the same RPM/Load.
I'm specifically talking about the added heat going into the oil from hotter surfaces inside the engine - specifically the top of the heads, the cylinder bores/liners, the bottom dome area and skirts of the pistons when massive amounts of HP are produced by the engine. That is what happens in the high HP Vette engine when running flat out for long duration on the race track (the subject of this thread). Those internal engine surfaces can increase in temperature well above what the cooling system is running at when you cram lots of fuel & air into a combustion chamber and explode it. The cooling system can't keep every surface inside the engine that comes in contact with the oil to 100 deg C. The surface of the cylinder wall the rings sweep across runs quite a bit hotter than the side of the cylinder wall that's in contact with the coolant.
Oil splashing up under the pistons and on the inside of the cylinder walls is heated up well above what any bearing is going to heat oil up to. A major part of oil function is to provide additional cooling to these surfaces, and by doing so the sump temperature will increase above from just the bearing's influence. That added heat from combustion at high HP levels on top of the heat generated by the bearing rotational RPM contributes to an overall higher sump temperature compared to not putting tons of power out at the same RPM. Goes along with my example of what the stabilized sump temperature difference would be if running the engine at 4000 RPM with a 30 HP load on the crank vs running the same engine running at 4000 RPM with a 300 HP load on the crank. The sump temperature is going to stabilize quite a bit higher under the 300 HP load condition due to the extra heat the oil picks up from hotter internal surfaces - especially if there is no oil cooler.
Originally Posted By: Shannow
Originally Posted By: userfriendly
As sump oil temperature rises and the oil thins, is less heat generated in the bearings?
Yep...
Doesn't mean the sump temperature can't still rise. There are other sources of heat going into the oil when the engine is putting out massive amounts of power.
Originally Posted By: userfriendly
As sump oil temperature rises and the oil thins, is less heat generated in the bearings?
Yep...
Doesn't mean the sump temperature can't still rise. There are other sources of heat going into the oil when the engine is putting out massive amounts of power.
Originally Posted By: Shannow
OK, talking specifically...provide DATA...specifically...
not feelings, guesses, or bets (Casino Royale if you will)
Post up the main link where those graphs came from - I bet they have nothing to do with what I'm talking about, which you try to skirt by whipping out unrelated information. Those graphs have nothing to do with what I'm talking about. You're not discussing the heat produced from making massive HP. All that heat from combustion can NOT be absorbed by the cooling system. If the engine doesn't have some insanely effective oil cooler, the oil temps will sky rocket in a long track event, especially if the engine is making a very high level HP.
I see you are "Mr. Snide Remark King" again ... thought you were a little more mature and got past that, but it's obvious you can't post up the right information to debunk what I'm saying about the extra heat that goes into the oil from making big HP.
OK, talking specifically...provide DATA...specifically...
not feelings, guesses, or bets (Casino Royale if you will)
Post up the main link where those graphs came from - I bet they have nothing to do with what I'm talking about, which you try to skirt by whipping out unrelated information. Those graphs have nothing to do with what I'm talking about. You're not discussing the heat produced from making massive HP. All that heat from combustion can NOT be absorbed by the cooling system. If the engine doesn't have some insanely effective oil cooler, the oil temps will sky rocket in a long track event, especially if the engine is making a very high level HP.
I see you are "Mr. Snide Remark King" again ... thought you were a little more mature and got past that, but it's obvious you can't post up the right information to debunk what I'm saying about the extra heat that goes into the oil from making big HP.
Originally Posted By: ZeeOSix
I see you are "Mr. Snide Remark King" again ...
Pot meet kettle...
Originally Posted By: ZeeOSix
GGuess it goes along with thinking a PD oil pump doesn't force any additional oil flow through the bearings either.
I see you are "Mr. Snide Remark King" again ...
Pot meet kettle...
Originally Posted By: ZeeOSix
GGuess it goes along with thinking a PD oil pump doesn't force any additional oil flow through the bearings either.
Originally Posted By: Shannow
For giggles, take the two examples shown, and with a Cp of 2.3KJ/KGK, and making the following assumptions (overly generous, not quite as stupid as a zero speed solution for bearing flows)
* Piston undercrown temperature is 300C
* the oil that contacts it reaches equilibrium at 300C
* density leaving the big end is 800Kg/m^3
* one half of the big end flow (the vertical component) reaches the piston underside to achieve that equilibrium.
Like I said, a ridiculously generous premise for heat transfer from the piston undercrown.
So in the first example, 4,000RPM, 1.16cc of oil hits the piston...0.928g, and is heated by 150C, so the ridiculously generous calculation is 320W, against a comparable amount of heating from a single main/big end.
Take the second, and the same boundary conditions and piston temperatures (piston temperatures can't be violated, engine fails if they do), and the contribution from undercrown temps is 480W, versus 590W from the rotating assembly.
As I said, wildly generous, as clearly not even close to 50% of the oil leaving the big end hits the piston underside...and the bearing surfaces here do not include the piston skirts and rings, which are another serious source of heating through viscous friction/shear, again diminishing the contribution to the "raging fire of the explosion of crammed molecules".
Here's a chart from a Ricardo paper...on the FMEP losses associated with different parts of an engine with speed. You can see how the frictional MEP of the reciprocating group changes with load (as the rings get loaded out), and is comparable to that of the crankshaft group.
For giggles, take the two examples shown, and with a Cp of 2.3KJ/KGK, and making the following assumptions (overly generous, not quite as stupid as a zero speed solution for bearing flows)
* Piston undercrown temperature is 300C
* the oil that contacts it reaches equilibrium at 300C
* density leaving the big end is 800Kg/m^3
* one half of the big end flow (the vertical component) reaches the piston underside to achieve that equilibrium.
Like I said, a ridiculously generous premise for heat transfer from the piston undercrown.
So in the first example, 4,000RPM, 1.16cc of oil hits the piston...0.928g, and is heated by 150C, so the ridiculously generous calculation is 320W, against a comparable amount of heating from a single main/big end.
Take the second, and the same boundary conditions and piston temperatures (piston temperatures can't be violated, engine fails if they do), and the contribution from undercrown temps is 480W, versus 590W from the rotating assembly.
As I said, wildly generous, as clearly not even close to 50% of the oil leaving the big end hits the piston underside...and the bearing surfaces here do not include the piston skirts and rings, which are another serious source of heating through viscous friction/shear, again diminishing the contribution to the "raging fire of the explosion of crammed molecules".
Here's a chart from a Ricardo paper...on the FMEP losses associated with different parts of an engine with speed. You can see how the frictional MEP of the reciprocating group changes with load (as the rings get loaded out), and is comparable to that of the crankshaft group.
Originally Posted By: Shannow
Originally Posted By: ZeeOSix
I see you are "Mr. Snide Remark King" again ...
Pot meet kettle...
Originally Posted By: ZeeOSix
Guess it goes along with thinking a PD oil pump doesn't force any additional oil flow through the bearings either.
Hey, that was a true statement I made.
Originally Posted By: ZeeOSix
I see you are "Mr. Snide Remark King" again ...
Pot meet kettle...
Originally Posted By: ZeeOSix
Guess it goes along with thinking a PD oil pump doesn't force any additional oil flow through the bearings either.
Hey, that was a true statement I made.
Originally Posted By: Shannow
OK, talking specifically...provide DATA...specifically...
not feelings, guesses, or bets (Casino Royale if you will)
Read this ... it's what I'm talking about and what you fail to understand. Again, you always just focus on the bearing ... "Bearing Royal" if you will.
"Engine Lubrication System Model for Sump Oil Temperature Prediction"
http://papers.sae.org/2001-01-1073/
Click on the "Preview Technical Paper" on the RH margin of the page. It only shows the 1st 5 pages (unless you want to buy the paper), but the BITOG link below summarizes this same SAE paper.
From the summary: "They showed that 75 percent of engine oil heat gain in wide open throttle, full load conditions, is from the piston undercrown and that 15 percent was from the main bearings."
https://bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=637273
That means 75% from combustion heat and basically the remaining 25% from bearing and other components friction (15% of which was main bearings) and the heat gain from other hot surfaces (besides the bottom of the piston crowns) caused by high combustion rates.
That is exactly why the sump temperature will increase significantly more when putting out 300 HP (or more) at 4000 RPM vs 30 HP at 4000 RPM. Heat of combustion has to go someplace, and the cooling system only absorbs part of it, the oil absorbs most of the rest, and a small fraction is lost through convection and radiation to the atmosphere (not a big effect). As said before, an oil cooler is paramount in keeping the sump oil temperature down if you are making big HP for long periods of time.
OK, talking specifically...provide DATA...specifically...
not feelings, guesses, or bets (Casino Royale if you will)
Read this ... it's what I'm talking about and what you fail to understand. Again, you always just focus on the bearing ... "Bearing Royal" if you will.
"Engine Lubrication System Model for Sump Oil Temperature Prediction"
http://papers.sae.org/2001-01-1073/
Click on the "Preview Technical Paper" on the RH margin of the page. It only shows the 1st 5 pages (unless you want to buy the paper), but the BITOG link below summarizes this same SAE paper.
From the summary: "They showed that 75 percent of engine oil heat gain in wide open throttle, full load conditions, is from the piston undercrown and that 15 percent was from the main bearings."
https://bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=637273
That means 75% from combustion heat and basically the remaining 25% from bearing and other components friction (15% of which was main bearings) and the heat gain from other hot surfaces (besides the bottom of the piston crowns) caused by high combustion rates.
That is exactly why the sump temperature will increase significantly more when putting out 300 HP (or more) at 4000 RPM vs 30 HP at 4000 RPM. Heat of combustion has to go someplace, and the cooling system only absorbs part of it, the oil absorbs most of the rest, and a small fraction is lost through convection and radiation to the atmosphere (not a big effect). As said before, an oil cooler is paramount in keeping the sump oil temperature down if you are making big HP for long periods of time.
AEHAAS summary of a paper that he paid for ?
which you didn't nor read the actual text ?
and you are relying on his interpretation of said document ?
he wrote oil university 101 (the original edition) for crying out loud.
YOU have the entire internet at your disposal, plus your training and textbooks, and you loop back to THAT ????
edit...I've paid for
http://papers.sae.org/2003-01-1993/
You can see the summary also...
which you didn't nor read the actual text ?
and you are relying on his interpretation of said document ?
he wrote oil university 101 (the original edition) for crying out loud.
YOU have the entire internet at your disposal, plus your training and textbooks, and you loop back to THAT ????
edit...I've paid for
http://papers.sae.org/2003-01-1993/
You can see the summary also...
Last edited:
Originally Posted By: ZeeOSix
That is exactly why the sump temperature will increase significantly more when putting out 300 HP (or more) at 4000 RPM vs 30 HP at 4000 RPM.
OK, So I measured 40C from RPM, and you are claiming more than 40C from load ???
That is exactly why the sump temperature will increase significantly more when putting out 300 HP (or more) at 4000 RPM vs 30 HP at 4000 RPM.
OK, So I measured 40C from RPM, and you are claiming more than 40C from load ???
My last post about SAE paper 2001-01-1073 pretty much nails it ... end of story. Go do the tests I suggested to prove it to yourself, or go buy that SAE paper if you think member AEHaas is incapable of understanding what the SAE paper said.
Originally Posted By: ZeeOSix
My last post about SAE paper 2001-01-1073 pretty much nails it ... end of story. Go do the tests I suggested to prove it to yourself, or go buy that SAE paper if you think member AEHaas is incapable of understanding what the SAE paper said.
Test enging was running 100C oil temperatures at 2,000RPM road load, which increased to 115C at 2,000RPM W.O.T...then 138 at 4,000 W.O.T.
Unfortunately they didn't do a 4,000RPM "road load" test to close the loop, nor did they include the heat balance for the 2,000RPM "road load" condition.
However, in the tables, they DO show that the contribution from the bearings rose from 13 to 19% between 2,000RPM and 4,000RPM W.O.T., while the heat through the piston dropped from 76% to 72%...Also states that piston friction is comensurate in magnitude to the thermal flow through the piston...BUT that heat isn't counted as it's going automatically to the cylinder walls and coolant.
Which gets to an important distinction between what you want to believe the paper says, and what the paper DOES.
In order to calculate sump temperature, it counts all of the thermal inputs TO the oil, and netts off the losses (heat sinks)...33% of the total energy at 2,000RPM is lost through the skirts, 24% at 4,000RPM W.O.T. never making it to the sump...i.e. a significant part of the heat INPUT from the Piston crown doesn't GET to the sump.
Getting back to your premise...
Originally Posted By: ZeeOSix
But if the engine was at 4000 RPM and towing a large trailer up a steep hill 10 miles long that needed WOT the whole way, the sump temperature is going to rise much higher than when just cruising at a low HP level at 4000 RPM on a flat road. The bearings are turning at 4000 RPM in both cases, but the increased sump temperature between the low HP and high HP levels is now due to the increased heat of combustion and the rising temperature of the engine mass conducting added heat into the oil.
The paper shows the following heat transfers FROM the oil to the heat sinks, directly contrary to your premise above.
Heat FROM Oil TO the lifter gallery area...720W at 2,000RPM, W.O.T. 2.54KW at 4,000RPM.
Heat FROM oil TO the camshaft housing ... 490W at 2,000RPM, 1.97KW at 4,000RPM.
Which is entirely counter to your P.O.V.that all these hot parts are heating the oil, these surfaces are (as per my premise) cooling, and transferring the heat to the coolant.
Note that the paper is modelling sump temperature with a bunch of sources and sinks, the sump being the final sink. The heat dissipation from the sump, as the final heat sink was 3.81KW for 4,000RPM W.O.T. versus 2.88KW for the 2,000RPM W.O.T. case versus a Total heat input 14.1KW and 7.2KW respectively.
So CLEARLY the majority of the heat load on the oil is gone, by being transferred into those "hot" components before it even makes it to the sump.
Note the heat generation by the bearings is 936W, and 2.68KW respectively, and a major portion of that oil ends up straight into the sump, with no "hot" internal surfaces to give heat to.
...I still maintain that the "Delta T" (note delta T, the premise for speccing higher viscosity in the OP's manual) between road speed operation and track operation is primarily due to the operation of the engine at higher speeds, not higher loads.
My last post about SAE paper 2001-01-1073 pretty much nails it ... end of story. Go do the tests I suggested to prove it to yourself, or go buy that SAE paper if you think member AEHaas is incapable of understanding what the SAE paper said.
Test enging was running 100C oil temperatures at 2,000RPM road load, which increased to 115C at 2,000RPM W.O.T...then 138 at 4,000 W.O.T.
Unfortunately they didn't do a 4,000RPM "road load" test to close the loop, nor did they include the heat balance for the 2,000RPM "road load" condition.
However, in the tables, they DO show that the contribution from the bearings rose from 13 to 19% between 2,000RPM and 4,000RPM W.O.T., while the heat through the piston dropped from 76% to 72%...Also states that piston friction is comensurate in magnitude to the thermal flow through the piston...BUT that heat isn't counted as it's going automatically to the cylinder walls and coolant.
Which gets to an important distinction between what you want to believe the paper says, and what the paper DOES.
In order to calculate sump temperature, it counts all of the thermal inputs TO the oil, and netts off the losses (heat sinks)...33% of the total energy at 2,000RPM is lost through the skirts, 24% at 4,000RPM W.O.T. never making it to the sump...i.e. a significant part of the heat INPUT from the Piston crown doesn't GET to the sump.
Getting back to your premise...
Originally Posted By: ZeeOSix
But if the engine was at 4000 RPM and towing a large trailer up a steep hill 10 miles long that needed WOT the whole way, the sump temperature is going to rise much higher than when just cruising at a low HP level at 4000 RPM on a flat road. The bearings are turning at 4000 RPM in both cases, but the increased sump temperature between the low HP and high HP levels is now due to the increased heat of combustion and the rising temperature of the engine mass conducting added heat into the oil.
The paper shows the following heat transfers FROM the oil to the heat sinks, directly contrary to your premise above.
Heat FROM Oil TO the lifter gallery area...720W at 2,000RPM, W.O.T. 2.54KW at 4,000RPM.
Heat FROM oil TO the camshaft housing ... 490W at 2,000RPM, 1.97KW at 4,000RPM.
Which is entirely counter to your P.O.V.that all these hot parts are heating the oil, these surfaces are (as per my premise) cooling, and transferring the heat to the coolant.
Note that the paper is modelling sump temperature with a bunch of sources and sinks, the sump being the final sink. The heat dissipation from the sump, as the final heat sink was 3.81KW for 4,000RPM W.O.T. versus 2.88KW for the 2,000RPM W.O.T. case versus a Total heat input 14.1KW and 7.2KW respectively.
So CLEARLY the majority of the heat load on the oil is gone, by being transferred into those "hot" components before it even makes it to the sump.
Note the heat generation by the bearings is 936W, and 2.68KW respectively, and a major portion of that oil ends up straight into the sump, with no "hot" internal surfaces to give heat to.
...I still maintain that the "Delta T" (note delta T, the premise for speccing higher viscosity in the OP's manual) between road speed operation and track operation is primarily due to the operation of the engine at higher speeds, not higher loads.
Kicked around here in this thread
https://bobistheoilguy.com/forums/ubbthreads.php/topics/4050761/Crankcase_oil_heating...though
Note BrocLuno's statement regarding skirts, appears that he's spot on there.
Couple of linked papers too...
https://bobistheoilguy.com/forums/ubbthreads.php/topics/4050761/Crankcase_oil_heating...though
Note BrocLuno's statement regarding skirts, appears that he's spot on there.
Couple of linked papers too...
http://naca.central.cranfield.ac.uk/reports/1940/naca-report-698.pdf
Analysis of an air cooled engine, posted before (somwhere) but still pertinent here.
Sealing off the piston undercrown from oil splash only increased piston temperature by 15F, leading the researchers to claim that the heat transfer to the oil was minimal (but squirters would clearly improve it).
Analysis of an air cooled engine, posted before (somwhere) but still pertinent here.
Sealing off the piston undercrown from oil splash only increased piston temperature by 15F, leading the researchers to claim that the heat transfer to the oil was minimal (but squirters would clearly improve it).
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