In installing a sensor for EOT, it's common to measure the sump temp. That's how I have done most of my installations. I wonder if anyone (in particular you CATERHAM) have any thoughts about other point to measure EOT that more accurately represents the higher stress point in the engine where oil temps might be higher? Seems to me, the sump oil is cooler that the oil in a hydrodynamic wedge at the bearing or drooling out after doing its job. I wouldn't think measuring in the OP circuit, say the main gallery, would be much different than the sump. A sender in the main cap might not be accurate because it would pick up combustion heat transmitted through the block. Maybe the sump is the best place and what I need is some idea how much hotter the oil might be running in other areas... which I have seen somewhere.
Engine Oil Temp Measuring Points
- Thread starter Jim Allen
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I was under the impression that most installs were in a galley. Typically easier than in the sump I would imagine. Why are you looking to find the max temp if you don't mind me asking?
I have looked at a lot of engine dynamometer test data over the years, and the maximum oil temperature is always in the sump. But if you want to know the oil temperature that is being supplied to the bearings, you should measure in the main oil gallery after the filter. Oil picks up maybe 10F in temperature going through the bearings, but it needs to get past the rotating assembly to get back to the sump. This is where it picks up most of its heat, being churned by the crank and rods.
Measuring oil temperature in the sump would give you an idea of how prone the oil would be to oxidation, but if you want to be able to calculate the actual viscosity of the oil being supplied to the bearings, you need gallery temperature.
Or why not measure both? (You seem to be a data hound.)
Measuring oil temperature in the sump would give you an idea of how prone the oil would be to oxidation, but if you want to be able to calculate the actual viscosity of the oil being supplied to the bearings, you need gallery temperature.
Or why not measure both? (You seem to be a data hound.)
A.Harmon: Data Hound... nay... I am a Data Mastiff. The gallery is difficult on the one engine I monitor most carefully. I have some options in the adapter that feeds to the bypass filter but I was saving those ports for a differential pressure gauge.
Cp3: I already monitor sump temp but max temp is more curiosity than anything. I imagine it differs from engine to engine but it would be nice to know what MY engine is doing as a learning experience. Most oil temp gauges I have seen lately are sump but there is plenty found in either locale. Many EFI engines have oil temp senders built in and if the particular EFI system allows it, you can monitor that parameter via a suitable programmer or OBD2 gauge set (like the ScanGageII).
Cp3: I already monitor sump temp but max temp is more curiosity than anything. I imagine it differs from engine to engine but it would be nice to know what MY engine is doing as a learning experience. Most oil temp gauges I have seen lately are sump but there is plenty found in either locale. Many EFI engines have oil temp senders built in and if the particular EFI system allows it, you can monitor that parameter via a suitable programmer or OBD2 gauge set (like the ScanGageII).
Originally Posted By: Jim Allen
A.Harmon: Data Hound... nay... I am a Data Mastiff.
Cool. I was just curious if there was something specific you would use that for. Too much information is fun, gives you something to ponder when you're bored!
Unfortunatley I can't get that info with an OBD2 Gauge, at least I haven't been able to confirm for sure. The Ecotec has 8 galley ports in the block and 1 or 2 in the head, so lot's of room for both. Just have to get the gauges and maybe a sandwich adapter for the G6.
It would be interesting to see the difference between galley and sump though...maybe before and after cooler....
A.Harmon: Data Hound... nay... I am a Data Mastiff.
Cool. I was just curious if there was something specific you would use that for. Too much information is fun, gives you something to ponder when you're bored!
Unfortunatley I can't get that info with an OBD2 Gauge, at least I haven't been able to confirm for sure. The Ecotec has 8 galley ports in the block and 1 or 2 in the head, so lot's of room for both. Just have to get the gauges and maybe a sandwich adapter for the G6.
It would be interesting to see the difference between galley and sump though...maybe before and after cooler....
Honestly it's not that important. I prefer the bottom of the sump as it seems to correlate most with OP.
The thing is once the oil is up to temperature, at elevated rev's with maximum oil pump flow, the oil is circulating through an engine very quickly indeed; a gallon of oil every 12-15 seconds. With a normal sized sump of 4-6 quarts the difference in oil temp's between the oil returning to the sump and the pick-up point for the oil pump is only a few degrees.
The thing is once the oil is up to temperature, at elevated rev's with maximum oil pump flow, the oil is circulating through an engine very quickly indeed; a gallon of oil every 12-15 seconds. With a normal sized sump of 4-6 quarts the difference in oil temp's between the oil returning to the sump and the pick-up point for the oil pump is only a few degrees.
It is very important where oil temps are measured in a trans or engine oil pan. There are differences, for sure!
The standard is the oil pan - it is the reference point for oil temp considerations.
Measuring elsewhere can certainly get you a hotter temperature reading [or maybe cooler!], but we already know that this occurs.
We know oil coming out of a turbo line is HOT.
The sump is best for averaging reference - what people go by.
The standard is the oil pan - it is the reference point for oil temp considerations.
Measuring elsewhere can certainly get you a hotter temperature reading [or maybe cooler!], but we already know that this occurs.
We know oil coming out of a turbo line is HOT.
The sump is best for averaging reference - what people go by.
I thought that I was pretty anal. But Jim Allen you are a valuable resource of information in real world performance. Please continue to post your findings.
Originally Posted By: A_Harman
...it needs to get past the rotating assembly to get back to the sump. This is where it picks up most of its heat, being churned by the crank and rods.
The crank and rods don't churn the oil, as the crank is always mounted well above the oil level. The rods/crank do sling the rod oil flow and create windage which may be what you mean.
The oil transfers heat anywhere it contacts the block and heads. The crank and rods are not an area of especially significant heat generation.
...it needs to get past the rotating assembly to get back to the sump. This is where it picks up most of its heat, being churned by the crank and rods.
The crank and rods don't churn the oil, as the crank is always mounted well above the oil level. The rods/crank do sling the rod oil flow and create windage which may be what you mean.
The oil transfers heat anywhere it contacts the block and heads. The crank and rods are not an area of especially significant heat generation.
It would be nice to have a well-placed head temp sensor.
Originally Posted By: CATERHAM
Honestly it's not that important. I prefer the bottom of the sump as it seems to correlate most with OP.
The thing is once the oil is up to temperature, at elevated rev's with maximum oil pump flow, the oil is circulating through an engine very quickly indeed; a gallon of oil every 12-15 seconds. With a normal sized sump of 4-6 quarts the difference in oil temp's between the oil returning to the sump and the pick-up point for the oil pump is only a few degrees.
Depending upon the engine, the oil flow can be even higher, about 6 GPM.
You guys would probably enjoy this tech article:
http://www.carcraft.com/techarticles/ccrp_0911_small_block_chevy_oil_pumps/viewall.html
Take a look at the thick vs. thin and oil pump test charts.
Honestly it's not that important. I prefer the bottom of the sump as it seems to correlate most with OP.
The thing is once the oil is up to temperature, at elevated rev's with maximum oil pump flow, the oil is circulating through an engine very quickly indeed; a gallon of oil every 12-15 seconds. With a normal sized sump of 4-6 quarts the difference in oil temp's between the oil returning to the sump and the pick-up point for the oil pump is only a few degrees.
Depending upon the engine, the oil flow can be even higher, about 6 GPM.
You guys would probably enjoy this tech article:
http://www.carcraft.com/techarticles/ccrp_0911_small_block_chevy_oil_pumps/viewall.html
Take a look at the thick vs. thin and oil pump test charts.
Originally Posted By: Bruce T
It would be nice to have a well-placed head temp sensor.
Well placed is the operative word as the temps vary dramatically in different areas of the head. In some areas the water jacket is as little as 2 mm thick (from the oil side) vs areas where it's 20 mm thick. Thats why a sump average is standard info.
It would be nice to have a well-placed head temp sensor.
Well placed is the operative word as the temps vary dramatically in different areas of the head. In some areas the water jacket is as little as 2 mm thick (from the oil side) vs areas where it's 20 mm thick. Thats why a sump average is standard info.
I had thought that the oil under pressure and load in the bearing and hotter connecting rods was a good bit hotter than the average sump temeprature. That's part of the reason HTHS is tested at 150 C since that may be the temperature of the oil film inside the bearing. I don't have any data handy that states that though. Of course it makes since to say oil in the bottom end and bearings is not as hot as oil flowing over the top end so I don't know if the oil in the bearing is running much hotter.
mechanicx is right on.
In my (industrial) bearings, there is a thermocouple contained in a well, the the oil exiting the bearing runs through, so the thermocouple is bathed with the oil that has just exited the bearing, and is representative of the actual oil operating temperature.
What this shows is typically a 40-45C rise across the bearing, while the return oil to the sump in bulk is only around 10C.
With this information, on each bearing, we tune the oil supply such that it's operating viscosity is optimum...temp too low, we reduce orifice size to that bearing. Too high, and we usually give that bearing a few more thou radial clearance.
Next best place is a thermocouple installed such that it's drilled to a couple of mm from the white metal face under the oil wedge...it's not as responsive, but still shows the 40-45C rise between supply and working temperature.
In my (industrial) bearings, there is a thermocouple contained in a well, the the oil exiting the bearing runs through, so the thermocouple is bathed with the oil that has just exited the bearing, and is representative of the actual oil operating temperature.
What this shows is typically a 40-45C rise across the bearing, while the return oil to the sump in bulk is only around 10C.
With this information, on each bearing, we tune the oil supply such that it's operating viscosity is optimum...temp too low, we reduce orifice size to that bearing. Too high, and we usually give that bearing a few more thou radial clearance.
Next best place is a thermocouple installed such that it's drilled to a couple of mm from the white metal face under the oil wedge...it's not as responsive, but still shows the 40-45C rise between supply and working temperature.
I've just installed a sensor to try right in the main oil channel on the block which runs directly from the pump.
So the temp is taken just before it is fed into the main bearings.
I will see next week what readings I get,
So the temp is taken just before it is fed into the main bearings.
I will see next week what readings I get,
Originally Posted By: Shannow
In my (industrial) bearings, there is a thermocouple contained in a well, the the oil exiting the bearing runs through, so the thermocouple is bathed with the oil that has just exited the bearing, and is representative of the actual oil operating temperature.
What this shows is typically a 40-45C rise across the bearing, while the return oil to the sump in bulk is only around 10C.
With this information, on each bearing, we tune the oil supply such that it's operating viscosity is optimum...temp too low, we reduce orifice size to that bearing. Too high, and we usually give that bearing a few more thou radial clearance.
Shannow, thanks for the insight with industrial bearings, but one would think that the oil flow through the bearings would have to be quite slow to generate a 40-45C rise in oil temp's.
In an automotive application with oil shooting through the bearings at a rate of 6 gal/minute, it seems hard to imagine more than a few degrees temp' increase from input to output.
In my (industrial) bearings, there is a thermocouple contained in a well, the the oil exiting the bearing runs through, so the thermocouple is bathed with the oil that has just exited the bearing, and is representative of the actual oil operating temperature.
What this shows is typically a 40-45C rise across the bearing, while the return oil to the sump in bulk is only around 10C.
With this information, on each bearing, we tune the oil supply such that it's operating viscosity is optimum...temp too low, we reduce orifice size to that bearing. Too high, and we usually give that bearing a few more thou radial clearance.
Shannow, thanks for the insight with industrial bearings, but one would think that the oil flow through the bearings would have to be quite slow to generate a 40-45C rise in oil temp's.
In an automotive application with oil shooting through the bearings at a rate of 6 gal/minute, it seems hard to imagine more than a few degrees temp' increase from input to output.
Bear in mind that is the bearing "outlet" temperature, not the working temp which is approximately half way between the inlet and outlet.
Oil flow is quite brisk at 2-5l/s depending on bearing.
40C rise across a bearing is fairly reasonable during the design phase, as you are doing quite a bit of "work" to the oil , which naturally increases it's temperature.
Check out the design parameters in this discussion
Should open a PDF
In an engine, as per my steam turbines, there are other parts of the lubricating circuit that don't apply work to the oil, such as squirters and hydraulic pistons, so the overall rise isn't 40C, but the average of worked and unworked oil.
http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2670293#Post2670293
Shows an extreme example.
As an aside, the mist of very hot oil being flung off crank journals, providing heat, and lots of surface area for oxidation is probably the most taxing part of a lubricant's job.
Oil flow is quite brisk at 2-5l/s depending on bearing.
40C rise across a bearing is fairly reasonable during the design phase, as you are doing quite a bit of "work" to the oil , which naturally increases it's temperature.
Check out the design parameters in this discussion
Should open a PDF
In an engine, as per my steam turbines, there are other parts of the lubricating circuit that don't apply work to the oil, such as squirters and hydraulic pistons, so the overall rise isn't 40C, but the average of worked and unworked oil.
http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2670293#Post2670293
Shows an extreme example.
As an aside, the mist of very hot oil being flung off crank journals, providing heat, and lots of surface area for oxidation is probably the most taxing part of a lubricant's job.
Just found this, and ran out of edit time on last post.
Ricardo Institute Testing.
Once again remembering that the bearing temperature is reflective of the "average" oil temp in the bearing (Ti+To)/2
Ricardo Institute Testing.
Once again remembering that the bearing temperature is reflective of the "average" oil temp in the bearing (Ti+To)/2
Shannow! This is good chit, man! This will be very nice to digest but it will take me some time to figure this out. One thing I think I see right off is that bearing temp goes up with rpms independent of supply oil temp. Even if these numbers are "representative" they still answer a lot of general questions for me.
Thanks so much for posting this
Thanks so much for posting this
No probs at all...
Lubricating systems are a complex but of gear, but physics is physics...work harder against the oil (revs), and it heats more. The oil thins, but the faster revs provide more film thickness.
Also, the faster they spin, the more they "suck" oil in, basically forming a "shear" driven pump to move more oil in
Lubricating systems are a complex but of gear, but physics is physics...work harder against the oil (revs), and it heats more. The oil thins, but the faster revs provide more film thickness.
Also, the faster they spin, the more they "suck" oil in, basically forming a "shear" driven pump to move more oil in
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