Understanding Viscosity and HTHS

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It falls back on the simple dynamic viscosity (plus the DI pack). That's good to know. Now I just need to confirm the bearing temperature is rising 50-60*F above pan temperature.
 
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Originally Posted by RDY4WAR
It falls back on the simple dynamic viscosity (plus the DI pack). That's good to know.
Yes, except most DI packs temporarily shear similar to a VII; so, the dynamic viscosity at low shear will be somewhat higher than the high-shear HTHS viscosity, depending on how much the DI pack temporarily shears.
 

ZeeOSix

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Originally Posted by RDY4WAR
Now I just need to confirm the bearing temperature is rising 50-60*F above pan temperature.
For a given viscosity, the engine RPM is going to be the biggest contributor to the oil temp rise from shearing inside the bearing. If the engine isn't revving at redline, it's probably much less than a 50-60 F rise. I'd say it's more long the lines of a 25-30 F rise (if that) if driving around normally.
 
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Originally Posted by ZeeOSix
Originally Posted by RDY4WAR
Now I just need to confirm the bearing temperature is rising 50-60*F above pan temperature.
For a given viscosity, the engine RPM is going to be the biggest contributor to the oil temp rise from shearing inside the bearing. If the engine isn't revving at redline, it's probably much less than a 50-60 F rise. I'd say it's more long the lines of a 25-30 F rise (if that) if driving around normally.
This engine flashes to 4100 rpm coming off the line (snapping the throttle from 850 rpm idle), shifts 1-2 @ 5800 rpm falling down to 4800 rpm in 2nd, shifts 2-3 @ 5600 rpm falling to 4700 rpm, and crosses the 1/4 mile in 3rd at around 5300 rpm. Not crazy high rpm. I'm also somewhat worried about aeration since the viscosity is in the 30-50 cSt range for much of the run.
 
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Originally Posted by RDY4WAR
Now I just need to confirm the bearing temperature is rising 50-60*F above pan temperature.
Only measurements that I can offer from personal experience (actual measured results) are from my turbine days. 45C oil supply temperatures...85-95C bearing exit temperatures, single pass. Whereas big ends get their oil supply from already used main bearing oil. I can offer this stuff lifted from a paper [Linked Image] [Linked Image]
 
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Originally Posted by RDY4WAR
Now I just need to confirm the bearing temperature is rising 50-60*F above pan temperature.
Only measurements that I can offer from personal experience (actual measured results) are from my turbine days. 45C oil supply temperatures...85-95C bearing exit temperatures, single pass. Whereas big ends get their oil supply from already used main bearing oil. I can offer this stuff lifted from a paper [Linked Image] [Linked Image]
 
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Take the 4,000RPM example. 2.38ml/sec, at 51W heat generation (1.7J/g/K) , that's a temperature rise of 12.6K across the big end 6,000RPM example the big end rise is 28.7K. note the metal temperatures in the examples also...
 
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So at 4000 rpm, that's a 22.7*F temp rise. At 6000 rpm, that's a 51.7*F temp rise. What's the equation to get the kelvin number?
 
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THe specific hear of the oil is around 1.7Joules/Gramme/K (1K equals 1C) so temperature rise is Watts(Joules per second)/Cubic centimetres per second/Specific Heat
 
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Originally Posted by Shannow
THe specific hear of the oil is around 1.7Joules/Gramme/K (1K equals 1C) so temperature rise is Watts(Joules per second)/Cubic centimetres per second/Specific Heat
I'm writing all of this down. Thank you!
 
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Originally Posted by Shannow
... so temperature rise is Watts(Joules per second)/Cubic centimetres per second/Specific Heat
You might need to stir density into that mix, too, or specify flow in grams/sec.
 
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Originally Posted by CR94
Originally Posted by Shannow
... so temperature rise is Watts(Joules per second)/Cubic centimetres per second/Specific Heat
You might need to stir density into that mix, too, or specify flow in grams/sec.
Excellent pick up... Delta T = Watts/Specific Heat/Flow rate/density
 
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Originally Posted by Gokhan
This also answers your previous question regarding why your monograde boutique oils appear to have VII in them according to my calculator: The DI pack shears as well. This was discovered in the paper about shear-thinning I linked above.
Out of curiosity, I wonder how things would work out in the wash with other types of oils with substantially different additive packages or virtually none, such as hydraulic oils or ND monogrades.
 
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