Viscosity Choice based on Oil temp

Pennzoil motor oil
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Originally Posted By: ZeeOSix
Some bearings can survive without pressure fed oil, and some can not ... it depends on many factors.


I challenge you (again) to provide a link to a journal/SAE paper that gives a specific requirement for the gallery pressure on these "pressure fed" bearings that you keep speaking about.

Nor Dr. Haas' 101, but something properly published and technically based that specifies the pressure required to provide the excess flow to keep bearings lubricated.

Even Ricardo, who have been the pinnacle of engine development for over 90 years talk only flow, with pressure sufficient to get it there.
 
Originally Posted By: ZeeOSix
Originally Posted By: userfriendly
I would assume that the amount of oil through the bearings "per revolution" decreases with rpm, because of the time factor.


The flow through a journal bearing increases due to RPM (even if not pressure fed), and also increases on top of that due to increased supply pressure.


I think that userfriendly is referreing back to the bearing design charts I posted in the other thread(s), where the "specific flow" per RPM decreases with RPM.

As per your chart...

full-37311-1741-engine_oil_flow_requirements.jpg


Yes, clearly flow increases with RPM, but the flow per REVOLUTION is clearly reduced.

The oil pump provides a linear volume/RPM curve, while the bearing oil requirement drops off.

It's why the OEMs are providing variable flow oil pumps, more flow/Rev at low RPM, and less at higher.

(you explained it in the racing thread as the other way around, demonstrating that you don't get it).
 
Originally Posted By: userfriendly
When the oil heats up due to high rpm it will become thinner, oil pressure will drop if the pump output is inadequate.
In this case would the solution be install a larger oil pump, or use a thicker oil?


Per Shannow, you don't need any oil pressure for bearings to survive.
wink.gif
 
Originally Posted By: Shannow
Originally Posted By: ZeeOSix
If you could just seal the oil film inside the bearing (no side leakage, meaning all the volume stays in the bearing), the bearing temperature would go sky high and the oil would break down and smoke the bearing in no time. As you increase the oil flow through the bearing, the temperature rise gets increasingly lower.


Of course it would, and that's the problem with ALL of your arguments.

You take a
* no shaft speed, pre-oiler supplies flow; and
* no side leakage, infinite temperature rise

as two bookends to base your position on...when they are two completely artificial constructs, that help YOUR sense of simplicity, in the absence of understanding.

Spin the shaft, oil leaks out the ends, and has to be replaced...that's reality.

And oil pumps provide that make-up oil.

And YES, enough pressure to get it to the big end, which as we've been over is typically only intermittently fed and does just fine.


As usual, you are spinning off course again. I replied to a specific question asked by userfriendly with the correct answer.

Yeah, we ALL know that oil leaks out of the end of a spinning journal bearing, but that wasn't the topic.
 
Originally Posted By: Shannow
Originally Posted By: ZeeOSix
Some bearings can survive without pressure fed oil, and some can not ... it depends on many factors.


I challenge you (again) to provide a link to a journal/SAE paper that gives a specific requirement for the gallery pressure on these "pressure fed" bearings that you keep speaking about.

Nor Dr. Haas' 101, but something properly published and technically based that specifies the pressure required to provide the excess flow to keep bearings lubricated.

Even Ricardo, who have been the pinnacle of engine development for over 90 years talk only flow, with pressure sufficient to get it there.


I challenge you to prove that a 500 HP V8 will last just as long at full power with only 5 PSI of oil pressure.
 
Originally Posted By: ZeeOSix
Originally Posted By: userfriendly
When the oil heats up due to high rpm it will become thinner, oil pressure will drop if the pump output is inadequate.
In this case would the solution be install a larger oil pump, or use a thicker oil?


Per Shannow, you don't need any oil pressure for bearings to survive.
wink.gif



Again, you are making up a position and stating that I am stating it...nice work...you must be an absolute pleasure to be around as a person

I have never once said that you don't need oil pressure...and I'd appreciate that you stop attributing it to me, as it's a lie that you keep perpetuating.

I have stated, time and time again, that you only need sufficient pressure to get the required volume to the bearings.
 
Originally Posted By: Shannow
and again, here are two google searches, one of which reveals actual papers, and one of which....well click on them and see.

Main Bearing Flow Requirements

Main Bearing Pressure Requirement


Here a quote from one of the hits. Guess those oil pumps don't really do much for lubrication after all. Normal passenger cars are no setup like NASCAR engines that only have to last 200 miles at WOT.

"One of the advantages of looser bearing clearances is that it allows more room for “slop,” which is important if the crankshaft isn’t machined to near perfection or there is some misalignment in the main bores. Wider bearing clearances do require a heavier viscosity oil (such as a 20W50 multi-viscosity oil or a straight 30, 40 or 50 oil). The heavier viscosity oil is absolutely necessary with wider clearances to maintain the oil film between the bearing and shaft so the bearing isn’t starved for lubrication. This also requires more oil pressure from the oil pump and/or more oil volume."
 
Originally Posted By: Shannow
Originally Posted By: ZeeOSix
Originally Posted By: userfriendly
When the oil heats up due to high rpm it will become thinner, oil pressure will drop if the pump output is inadequate.
In this case would the solution be install a larger oil pump, or use a thicker oil?


Per Shannow, you don't need any oil pressure for bearings to survive.
wink.gif



Again, you are making up a position and stating that I am stating it...nice work...you must be an absolute pleasure to be around as a person

I have never once said that you don't need oil pressure...and I'd appreciate that you stop attributing it to me, as it's a lie that you keep perpetuating.

I have stated, time and time again, that you only need sufficient pressure to get the required volume to the bearings.


So it that's true, then my 500 HP V8 should last just fine at WOT with only 5 PSI of oil pressure. Don't think so. You fail to realize that a large part of the reason pressure fed bearings exist today is to help keep the temperature down on the bearings and oil which increases longevity of the engine.
 
Originally Posted By: Shannow
Originally Posted By: ZeeOSix
Originally Posted By: userfriendly
I would assume that the amount of oil through the bearings "per revolution" decreases with rpm, because of the time factor.


The flow through a journal bearing increases due to RPM (even if not pressure fed), and also increases on top of that due to increased supply pressure.


I think that userfriendly is referreing back to the bearing design charts I posted in the other thread(s), where the "specific flow" per RPM decreases with RPM.

As per your chart...

full-37311-1741-engine_oil_flow_requirements.jpg


Yes, clearly flow increases with RPM, but the flow per REVOLUTION is clearly reduced.

The oil pump provides a linear volume/RPM curve, while the bearing oil requirement drops off.

It's why the OEMs are providing variable flow oil pumps, more flow/Rev at low RPM, and less at higher.

(you explained it in the racing thread as the other way around, demonstrating that you don't get it).


I wasn't discussing "flow per RPM change" as RPM increases. Yeah, we've discussed this already to nausea and seem to agree on that fact. You're going off track again to try and grasp some kind of straw.
 
OK, again...find me something in a paper/journal that states that current design practice in production engines is to overfeed the bearings to control temperatures.

Not a "magazine" article on race engine...a proper paper, SAE, Ricardo or the like.

OEMs are REDUCING oil pump volumes currently...which is diametrically opposite to your premise.
 
Originally Posted By: ZeeOSix
nausea


It's nauseam ... and if you recall, it was I who dragged YOU there...from your stationary shaft mis interpretation.
 
Originally Posted By: Shannow
OK, again...find me something in a paper/journal that states that current design practice in production engines is to overfeed the bearings to control temperatures.

Not a "magazine" article on race engine...a proper paper, SAE, Ricardo or the like.

OEMs are REDUCING oil pump volumes currently...which is diametrically opposite to your premise.


They may be reducing the pump flow at higher RPM, but I'll bet there is still a temperature rise design factor involved. If there was no real need for any pressure above a few PSI above ATM in the galleries then that's what they would design to. But that's still not the case even with variable flow PD pumps.
 
Originally Posted By: Shannow
Originally Posted By: ZeeOSix
nausea


It's nauseam ... and if you recall, it was I who dragged YOU there...from your stationary shaft mis interpretation.


In this case "nausea" is totally appropriate and more fitting ... exactly what I meant.
grin.gif


http://www.merriam-webster.com/dictionary/nausea
 
Originally Posted By: Shannow
OK, again...find me something in a paper/journal that states that current design practice in production engines is to overfeed the bearings to control temperatures.

Not a "magazine" article on race engine...a proper paper, SAE, Ricardo or the like.

OEMs are REDUCING oil pump volumes currently...which is diametrically opposite to your premise.
CAFE standards and emissions drive eveything.
 
Originally Posted By: Shannow
Originally Posted By: ZeeOSix
but I'll bet


Stop betting...deliver a paper or something...


You deliver a paper ... you're capable.
 
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