4WD
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Geomertric Dimensioning & Tolerancing ...
Used in valve manufacturing as well …
Used in valve manufacturing as well …
Low Viscosity doesn't have to mean low quality
- Thread starter StevieC
- Start date
- Status
Thanks 4WD!
Originally Posted by StevieC
In Amsoil's case for their Signature Series, they don't use a lot of VII's or any at all depending on the multi-weight formulation and rely on quality base oils instead for the properties they are looking for. I confirmed this by AMSOIL's technical line in an e-mail. They will confirm it for anyone that asks. Although it is further confirmed on the extended drain intervals we see where the oil's properties hasn't changed much from original.
"Don't use a lot"...not very scientific, and I'm sure that they are willing to tell anyone who calls similar. That's even less technical than the error riddle "paper" that started the thread.
OK, Amsoil ACD...which to be sold as a 30 NEEDS to be VII free...Oh, there's that pesky 4 ball in the data sheet too (and it's not even two years old...you know how I keep saying that the actual engine tests are a RECENT thing)...anyway, VI 146, which is exceptional for a monograde...I LOVE this oil. Just can't get it without getting raped in Oz.
https://www.amsoil.com/lit/databulletins/g27.pdf
Here's virgin spectrasyn 10
http://exxonmobilchemical.ides.com/en-US/ds244607/SpectraSynâ„¢%2010.aspx?I=30156&U=1
VI of 137, which makes me wonder about the "mono" in ACD.
So anything more than these two is affected by VIIs.
Signature Series
https://www.amsoil.com/lit/databulletins/g2880.pdf
ASM 0W20 - VI 169, so clearly contains VII, and a reasonable amount - Harman Index 0.903
ASL 5W30 - VI 162, again, clearly influenced by VII - Harman Index 0.931
AZF 0W40 - VI 184, again, clearly influenced heavily by VII - Harman Index 0.797
Let's see how they go against the "neutered" M1 EP range.
M1 0W20 - VI 173, so clearly contains an reasonable amount of VII - Harman Index 0.926 (clearly less effect of VII than the ASM)
M1 5W30 - VI 169, clearly influenced by VII - Harman Index 0.883
M1 0W40 ESP - VI 191 (calculated off Widman) - Harman Index 0.836
So as you can see, Amsoil's claim of "not a lot", when compared to the API licenced offerings indicates that their most closest competitor is also using "not a lot" also.
They were NEVER going to tell you that with all their "quality ingredients" that they used "about the same amount of their competitors".
You need to stop taking every bit of marketing as gospel fact....
edit...ooops Gokhan beat me to it.
In Amsoil's case for their Signature Series, they don't use a lot of VII's or any at all depending on the multi-weight formulation and rely on quality base oils instead for the properties they are looking for. I confirmed this by AMSOIL's technical line in an e-mail. They will confirm it for anyone that asks. Although it is further confirmed on the extended drain intervals we see where the oil's properties hasn't changed much from original.
"Don't use a lot"...not very scientific, and I'm sure that they are willing to tell anyone who calls similar. That's even less technical than the error riddle "paper" that started the thread.
OK, Amsoil ACD...which to be sold as a 30 NEEDS to be VII free...Oh, there's that pesky 4 ball in the data sheet too (and it's not even two years old...you know how I keep saying that the actual engine tests are a RECENT thing)...anyway, VI 146, which is exceptional for a monograde...I LOVE this oil. Just can't get it without getting raped in Oz.
https://www.amsoil.com/lit/databulletins/g27.pdf
Here's virgin spectrasyn 10
http://exxonmobilchemical.ides.com/en-US/ds244607/SpectraSynâ„¢%2010.aspx?I=30156&U=1
VI of 137, which makes me wonder about the "mono" in ACD.
So anything more than these two is affected by VIIs.
Signature Series
https://www.amsoil.com/lit/databulletins/g2880.pdf
ASM 0W20 - VI 169, so clearly contains VII, and a reasonable amount - Harman Index 0.903
ASL 5W30 - VI 162, again, clearly influenced by VII - Harman Index 0.931
AZF 0W40 - VI 184, again, clearly influenced heavily by VII - Harman Index 0.797
Let's see how they go against the "neutered" M1 EP range.
M1 0W20 - VI 173, so clearly contains an reasonable amount of VII - Harman Index 0.926 (clearly less effect of VII than the ASM)
M1 5W30 - VI 169, clearly influenced by VII - Harman Index 0.883
M1 0W40 ESP - VI 191 (calculated off Widman) - Harman Index 0.836
So as you can see, Amsoil's claim of "not a lot", when compared to the API licenced offerings indicates that their most closest competitor is also using "not a lot" also.
They were NEVER going to tell you that with all their "quality ingredients" that they used "about the same amount of their competitors".
You need to stop taking every bit of marketing as gospel fact....
edit...ooops Gokhan beat me to it.
Last edited by a moderator:
Originally Posted by Shannow
Originally Posted by ZeeOSix
Ford has been going with less piston skirt contact area, and anti-friction coating on the piston skirts. Minimizing ring tension to reduce friction is another trick. But going too far in those areas to reduce friction and HP lost can cause priblems like piston slap and oil consumption.
Can definitely see that over the years, with full barrel skirts turning into "G String" looking things, anti friction coatings, fatigue of the skirt "tongues", and as you say piston slap and partial skirt collapse.
Pendulums, when intent is applied regularly go too far.
FYI ... J&E forged pistons in the Gen3 Coyote (5.0L).
http://blog.jepistons.com/introducing-jes-2018-ford-coyote-5.0l-pistons
Article about J&E's piston skirt coating.
http://blog.jepistons.com/jes-patented-perfect-skirt-coating-is-a-breakthrough-in-piston-technology
Originally Posted by ZeeOSix
Ford has been going with less piston skirt contact area, and anti-friction coating on the piston skirts. Minimizing ring tension to reduce friction is another trick. But going too far in those areas to reduce friction and HP lost can cause priblems like piston slap and oil consumption.
Can definitely see that over the years, with full barrel skirts turning into "G String" looking things, anti friction coatings, fatigue of the skirt "tongues", and as you say piston slap and partial skirt collapse.
Pendulums, when intent is applied regularly go too far.
FYI ... J&E forged pistons in the Gen3 Coyote (5.0L).
http://blog.jepistons.com/introducing-jes-2018-ford-coyote-5.0l-pistons
Article about J&E's piston skirt coating.
http://blog.jepistons.com/jes-patented-perfect-skirt-coating-is-a-breakthrough-in-piston-technology
OVERKILL
$100 Site Donor 2021
Originally Posted by ZeeOSix
Originally Posted by Shannow
Originally Posted by ZeeOSix
Ford has been going with less piston skirt contact area, and anti-friction coating on the piston skirts. Minimizing ring tension to reduce friction is another trick. But going too far in those areas to reduce friction and HP lost can cause priblems like piston slap and oil consumption.
Can definitely see that over the years, with full barrel skirts turning into "G String" looking things, anti friction coatings, fatigue of the skirt "tongues", and as you say piston slap and partial skirt collapse.
Pendulums, when intent is applied regularly go too far.
FYI ... J&E forged pistons in the Gen3 Coyote (5.0L).
http://blog.jepistons.com/introducing-jes-2018-ford-coyote-5.0l-pistons
Article about J&E's piston skirt coating.
http://blog.jepistons.com/jes-patented-perfect-skirt-coating-is-a-breakthrough-in-piston-technology
Originally Posted by JE
But these changes present challenges to the piston designer as well, since as an enthusiast adds boost and more power to the engine, eventually there comes a breaking point—literally—where the rotating assembly must be upgraded to support these elevated power levels. That's where JE's pistons enter the equation.
I don't think they are included in the 3rd gen Coyote, as per the first link, if that's what is being implied (my apologies if that's not what you meant):
Originally Posted by Shannow
Originally Posted by ZeeOSix
Ford has been going with less piston skirt contact area, and anti-friction coating on the piston skirts. Minimizing ring tension to reduce friction is another trick. But going too far in those areas to reduce friction and HP lost can cause priblems like piston slap and oil consumption.
Can definitely see that over the years, with full barrel skirts turning into "G String" looking things, anti friction coatings, fatigue of the skirt "tongues", and as you say piston slap and partial skirt collapse.
Pendulums, when intent is applied regularly go too far.
FYI ... J&E forged pistons in the Gen3 Coyote (5.0L).
http://blog.jepistons.com/introducing-jes-2018-ford-coyote-5.0l-pistons
Article about J&E's piston skirt coating.
http://blog.jepistons.com/jes-patented-perfect-skirt-coating-is-a-breakthrough-in-piston-technology
Originally Posted by JE
But these changes present challenges to the piston designer as well, since as an enthusiast adds boost and more power to the engine, eventually there comes a breaking point—literally—where the rotating assembly must be upgraded to support these elevated power levels. That's where JE's pistons enter the equation.
I don't think they are included in the 3rd gen Coyote, as per the first link, if that's what is being implied (my apologies if that's not what you meant):
Last edited by a moderator:
On the subject of GD&T in reference to rod and main bearings, I've been thinking about how a crank journal moves inside the bearings. Ideally, you'd want the crank journal to remain as concentric as possible to reduce the reliance on the oil wedge and provide a more even distribution of pressure across the bearing surface. It would seem to me that a tighter clearance, combined with an oil with a high HTHS, would keep the journal more concentric. This would go against the trend for racing engine builders to open up bearing clearances to .0030" or greater. It would appear to me, and my limited experience in the field outside of assembling a dozen or so engines, that a wider clearance would decrease concentricity regardless of the oil used. While a thicker oil film from a 50 or 60 grade oil may make up for some of the reduced concentricity, it still won't work as well as a tighter clearance. This less concentric motion of the journal, in my view, would increase the peak pressure on the bearing at TDC and BDC, attempting to stretch the bearing out into an egg shape, increasing bearing fatique.
4WD
$50 site donor 2024
Nice post … think my $5/quart M1 EP 0w20 is not a bad deal … and since they supply thier own GIV/GIII & the VM … that's part of keeping the cost where it is …
RDY4WAR interesting perspective. The thing with forcing higher (excessive?) HTHS lubes through an abnormally tight bearing reduces the 'turnover' of the oil flowing through the bearing- it stagnates longer and as such accepts more bearing-generated heat per volume of flow. Combine that with the increased shear (both from 50/60? viscosity and tightened clearance) would spike the rate of heat generation and subsequently the bearing temperature. The extra shear viscosity that you would expect to cushion the cyclic loading may not be present as a result of further viscosity drop in the bearing from increased drag/heat and reduced throughput. Not to mention the actual clearance would be much tighter, leaving the bearing with less "wiggle room", perhaps increasing the original problem.
Then there is the fixed design parameters like bearing diameter will pretty much lock in an ideal bearing shear viscosity for maintaining EHL, and bearing width which would affect the "dwell time" of the oil moving through it, as it travels from feed hole to bearing side.
There are actual bearing experts in this thread that can set the record straight though
Then there is the fixed design parameters like bearing diameter will pretty much lock in an ideal bearing shear viscosity for maintaining EHL, and bearing width which would affect the "dwell time" of the oil moving through it, as it travels from feed hole to bearing side.
There are actual bearing experts in this thread that can set the record straight though
Last edited by a moderator:
Originally Posted by RDY4WAR
On the subject of GD&T in reference to rod and main bearings, I've been thinking about how a crank journal moves inside the bearings. Ideally, you'd want the crank journal to remain as concentric as possible to reduce the reliance on the oil wedge and provide a more even distribution of pressure across the bearing surface. It would seem to me that a tighter clearance, combined with an oil with a high HTHS, would keep the journal more concentric. This would go against the trend for racing engine builders to open up bearing clearances to .0030" or greater. It would appear to me, and my limited experience in the field outside of assembling a dozen or so engines, that a wider clearance would decrease concentricity regardless of the oil used. While a thicker oil film from a 50 or 60 grade oil may make up for some of the reduced concentricity, it still won't work as well as a tighter clearance. This less concentric motion of the journal, in my view, would increase the peak pressure on the bearing at TDC and BDC, attempting to stretch the bearing out into an egg shape, increasing bearing fatique.
Here is a good read about journal bearings.
Understanding Journal Bearings
On the subject of GD&T in reference to rod and main bearings, I've been thinking about how a crank journal moves inside the bearings. Ideally, you'd want the crank journal to remain as concentric as possible to reduce the reliance on the oil wedge and provide a more even distribution of pressure across the bearing surface. It would seem to me that a tighter clearance, combined with an oil with a high HTHS, would keep the journal more concentric. This would go against the trend for racing engine builders to open up bearing clearances to .0030" or greater. It would appear to me, and my limited experience in the field outside of assembling a dozen or so engines, that a wider clearance would decrease concentricity regardless of the oil used. While a thicker oil film from a 50 or 60 grade oil may make up for some of the reduced concentricity, it still won't work as well as a tighter clearance. This less concentric motion of the journal, in my view, would increase the peak pressure on the bearing at TDC and BDC, attempting to stretch the bearing out into an egg shape, increasing bearing fatique.
Here is a good read about journal bearings.
Understanding Journal Bearings
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Originally Posted by PeterPolyol
RDY4WAR intersting perspective. The thing with forcing higher (excessive?) HTHS lubes through an abnormally tight bearing reduces the 'turnover' of the oil flowing through the bearing- it stagnates longer and as such accepts more bearing-generated heat per volume of flow. Combine that with the increased shear (both from 50/60? viscosity and tightened clearance) would spike the rate of heat generation and subsequently the bearing temperature. The extra shear viscosity that you would expect to cushion the cyclic loading may not be present as a result of further viscosity drop in the bearing from increased drag/heat and reduced throughput. Not to mention the actual clearance would be much tighter, leaving the bearing with less "wiggle room", perhaps increasing the original problem.
Then there is the fixed design parameters like bearing diameter will pretty much lock in an ideal bearing shear viscosity for maintaining EHL, and bearing width which would affect the "dwell time" of the oil moving through it, as it travels from feed hole to beaing side.
There are actual bearing experts in this thead that can set the record straight though
I should've been more clear. I wasn't referring to using a 50 or 60 grade (5.0+ cP HTHS) with tight clearances. I meant instead being forced into a 50 or 60 grade oil with wide clearances, why not instead run tighter clearances with something like a stout 20 or 30 grade. For example, a quality synthetic 10w-30 with no VIIs and an HTHS of around 3.5 cP. Would the more concentric loading of the bearing be more gentle to a lower oil grade than a less concentric pairing with the same low grade, and if so, why the continued recommendation of wide clearances for racing engines.
Originally Posted by KrisZ
Originally Posted by RDY4WAR
On the subject of GD&T in reference to rod and main bearings, I've been thinking about how a crank journal moves inside the bearings. Ideally, you'd want the crank journal to remain as concentric as possible to reduce the reliance on the oil wedge and provide a more even distribution of pressure across the bearing surface. It would seem to me that a tighter clearance, combined with an oil with a high HTHS, would keep the journal more concentric. This would go against the trend for racing engine builders to open up bearing clearances to .0030" or greater. It would appear to me, and my limited experience in the field outside of assembling a dozen or so engines, that a wider clearance would decrease concentricity regardless of the oil used. While a thicker oil film from a 50 or 60 grade oil may make up for some of the reduced concentricity, it still won't work as well as a tighter clearance. This less concentric motion of the journal, in my view, would increase the peak pressure on the bearing at TDC and BDC, attempting to stretch the bearing out into an egg shape, increasing bearing fatique.
Here is a good read about journal bearings.
Understanding Journal Bearings
That's a good link I hadn't stumbled across yet. I've saved it to read here shortly.
RDY4WAR intersting perspective. The thing with forcing higher (excessive?) HTHS lubes through an abnormally tight bearing reduces the 'turnover' of the oil flowing through the bearing- it stagnates longer and as such accepts more bearing-generated heat per volume of flow. Combine that with the increased shear (both from 50/60? viscosity and tightened clearance) would spike the rate of heat generation and subsequently the bearing temperature. The extra shear viscosity that you would expect to cushion the cyclic loading may not be present as a result of further viscosity drop in the bearing from increased drag/heat and reduced throughput. Not to mention the actual clearance would be much tighter, leaving the bearing with less "wiggle room", perhaps increasing the original problem.
Then there is the fixed design parameters like bearing diameter will pretty much lock in an ideal bearing shear viscosity for maintaining EHL, and bearing width which would affect the "dwell time" of the oil moving through it, as it travels from feed hole to beaing side.
There are actual bearing experts in this thead that can set the record straight though
I should've been more clear. I wasn't referring to using a 50 or 60 grade (5.0+ cP HTHS) with tight clearances. I meant instead being forced into a 50 or 60 grade oil with wide clearances, why not instead run tighter clearances with something like a stout 20 or 30 grade. For example, a quality synthetic 10w-30 with no VIIs and an HTHS of around 3.5 cP. Would the more concentric loading of the bearing be more gentle to a lower oil grade than a less concentric pairing with the same low grade, and if so, why the continued recommendation of wide clearances for racing engines.
Originally Posted by KrisZ
Originally Posted by RDY4WAR
On the subject of GD&T in reference to rod and main bearings, I've been thinking about how a crank journal moves inside the bearings. Ideally, you'd want the crank journal to remain as concentric as possible to reduce the reliance on the oil wedge and provide a more even distribution of pressure across the bearing surface. It would seem to me that a tighter clearance, combined with an oil with a high HTHS, would keep the journal more concentric. This would go against the trend for racing engine builders to open up bearing clearances to .0030" or greater. It would appear to me, and my limited experience in the field outside of assembling a dozen or so engines, that a wider clearance would decrease concentricity regardless of the oil used. While a thicker oil film from a 50 or 60 grade oil may make up for some of the reduced concentricity, it still won't work as well as a tighter clearance. This less concentric motion of the journal, in my view, would increase the peak pressure on the bearing at TDC and BDC, attempting to stretch the bearing out into an egg shape, increasing bearing fatique.
Here is a good read about journal bearings.
Understanding Journal Bearings
That's a good link I hadn't stumbled across yet. I've saved it to read here shortly.
RDY4WAR, that's what I like to see...questioning minds.
It's the eccentricity that enables the oil "wedge" to be developed, and therefore resist the applied load. It's a yin and yang thing...no load, no eccentricity, not hydrodynamic lubrication, but no need to.
Here's a bearing characteristic curve that might help Bottom scale is Somerfeld number...if you look at the right hand side of that characteristic number you can see what's usually the parameters for the Stribeck curve.
r is radius, c is radial clearance, u is viscosity, N is rotational speed, P is applied pressure (load/(L*D))
So you can see that reducing radial clearance, just as you've intuited increases film thickness, or allows a lower viscosity for the same design point.
Closing up clearances requires a stiffer crank and block, which the OEMs are doing with deep skirts and cross bolting.
Race engines are typically stressing the limits of cranks and blocks, so need the clearances to allow them to do the "hoochie koochie" (as Smokey called it), without contacting, or transferring too much load between bearings. Heck, some times they even reduce journal diameter for less friction
It's the eccentricity that enables the oil "wedge" to be developed, and therefore resist the applied load. It's a yin and yang thing...no load, no eccentricity, not hydrodynamic lubrication, but no need to.
Here's a bearing characteristic curve that might help Bottom scale is Somerfeld number...if you look at the right hand side of that characteristic number you can see what's usually the parameters for the Stribeck curve.
r is radius, c is radial clearance, u is viscosity, N is rotational speed, P is applied pressure (load/(L*D))
So you can see that reducing radial clearance, just as you've intuited increases film thickness, or allows a lower viscosity for the same design point.
Closing up clearances requires a stiffer crank and block, which the OEMs are doing with deep skirts and cross bolting.
Race engines are typically stressing the limits of cranks and blocks, so need the clearances to allow them to do the "hoochie koochie" (as Smokey called it), without contacting, or transferring too much load between bearings. Heck, some times they even reduce journal diameter for less friction
Originally Posted by OVERKILL
I don't think they are included in the 3rd gen Coyote, as per the first link, if that's what is being implied (my apologies if that's not what you meant):
Originally Posted by JE
But these changes present challenges to the piston designer as well, since as an enthusiast adds boost and more power to the engine, eventually there comes a breaking point—literally—where the rotating assembly must be upgraded to support these elevated power levels. That's where JE's pistons enter the equation.
Yep, you're right ... those J&E are aftermarket forged pistons. I think all generations of the Coyote have OEM hypereutectic pistons - but they do have the J&E skirt coating as said in that other J&E link. The Boss 302 (engine designated "Road Runner") did have forged aluminum pistons however.
https://lmr.com/products/differences-between-mustang-5-0-coyote-engines
I don't think they are included in the 3rd gen Coyote, as per the first link, if that's what is being implied (my apologies if that's not what you meant):
Originally Posted by JE
But these changes present challenges to the piston designer as well, since as an enthusiast adds boost and more power to the engine, eventually there comes a breaking point—literally—where the rotating assembly must be upgraded to support these elevated power levels. That's where JE's pistons enter the equation.
Yep, you're right ... those J&E are aftermarket forged pistons. I think all generations of the Coyote have OEM hypereutectic pistons - but they do have the J&E skirt coating as said in that other J&E link. The Boss 302 (engine designated "Road Runner") did have forged aluminum pistons however.
https://lmr.com/products/differences-between-mustang-5-0-coyote-engines
Great read, Shannow. That fills in the gaps.
Let's take an example engine. A race engine that's been clearanced from OEM .0010-.0014" up to .0022-.0024". Is a higher viscosity oil (say 20w-50) absolutely necessary or could a lower viscosity (like 10w-30) still be used? Certainly the lower viscosity would increase eccentricity of the journal which, going by your information, would develop a greater wedge but lower the minimum film thickness. Would the stiffness of a more concentric journal still transfer more stress to the bearing and cap/block than a more eccentric bearing with a thinner MOFT?
Could higher oil pump pressure, from a high volume pump, make up for any shortcomings of a lower viscosity in this situation?
Since eccentricity decreases with rpm, is this why a higher viscosity is required at high rpm to maintain a sufficient film thickness when the oil wedge effectiveness is reduced?
I'm about to start reading that paper that was linked.
Let's take an example engine. A race engine that's been clearanced from OEM .0010-.0014" up to .0022-.0024". Is a higher viscosity oil (say 20w-50) absolutely necessary or could a lower viscosity (like 10w-30) still be used? Certainly the lower viscosity would increase eccentricity of the journal which, going by your information, would develop a greater wedge but lower the minimum film thickness. Would the stiffness of a more concentric journal still transfer more stress to the bearing and cap/block than a more eccentric bearing with a thinner MOFT?
Could higher oil pump pressure, from a high volume pump, make up for any shortcomings of a lower viscosity in this situation?
Since eccentricity decreases with rpm, is this why a higher viscosity is required at high rpm to maintain a sufficient film thickness when the oil wedge effectiveness is reduced?
I'm about to start reading that paper that was linked.
OVERKILL
$100 Site Donor 2021
Originally Posted by ZeeOSix
Originally Posted by OVERKILL
I don't think they are included in the 3rd gen Coyote, as per the first link, if that's what is being implied (my apologies if that's not what you meant):
Originally Posted by JE
But these changes present challenges to the piston designer as well, since as an enthusiast adds boost and more power to the engine, eventually there comes a breaking point—literally—where the rotating assembly must be upgraded to support these elevated power levels. That's where JE's pistons enter the equation.
Yep, you're right ... those J&E are aftermarket forged pistons. I think all generations of the Coyote have OEM hypereutectic pistons - but they do have the J&E skirt coating as said in that other J&E link. The Boss 302 (engine designated "Road Runner") did have forged aluminum pistons however.
https://lmr.com/products/differences-between-mustang-5-0-coyote-engines
Yeah, Ford's used "better" slugs in various engines over the years. My '87 GT had forged pistons, the 2000 Cobra R had H-beam rods and I THINK JE forged pistons? They were a well regarded brand in any case. Then of course there are the forged beauties in the 2003/2004 Terminator....etc.
Originally Posted by OVERKILL
I don't think they are included in the 3rd gen Coyote, as per the first link, if that's what is being implied (my apologies if that's not what you meant):
Originally Posted by JE
But these changes present challenges to the piston designer as well, since as an enthusiast adds boost and more power to the engine, eventually there comes a breaking point—literally—where the rotating assembly must be upgraded to support these elevated power levels. That's where JE's pistons enter the equation.
Yep, you're right ... those J&E are aftermarket forged pistons. I think all generations of the Coyote have OEM hypereutectic pistons - but they do have the J&E skirt coating as said in that other J&E link. The Boss 302 (engine designated "Road Runner") did have forged aluminum pistons however.
https://lmr.com/products/differences-between-mustang-5-0-coyote-engines
Yeah, Ford's used "better" slugs in various engines over the years. My '87 GT had forged pistons, the 2000 Cobra R had H-beam rods and I THINK JE forged pistons? They were a well regarded brand in any case. Then of course there are the forged beauties in the 2003/2004 Terminator....etc.
Originally Posted by RDY4WAR
Could higher oil pump pressure, from a high volume pump, make up for any shortcomings of a lower viscosity in this situation?
Since eccentricity decreases with rpm, is this why a higher viscosity is required at high rpm to maintain a sufficient film thickness when the oil wedge effectiveness is reduced?
You get more MOFT with both more RPM and with higher oil viscosity. But you also get higher localized oil shearing (friction) and temperature rise at higher RPM. But the offset seems to still give increased MOFT at higher RPM.
A high volume oil pump (which also increases oil pressure) won't necessarily increase MOFT due to the actual increased pressure. But the increase in the forced flow volume through the bearings may lower the localized oil temperature inside the journal bearing, which would translate to slightly higher localized viscosity that could add some slight increase in MOFT.
Could higher oil pump pressure, from a high volume pump, make up for any shortcomings of a lower viscosity in this situation?
Since eccentricity decreases with rpm, is this why a higher viscosity is required at high rpm to maintain a sufficient film thickness when the oil wedge effectiveness is reduced?
You get more MOFT with both more RPM and with higher oil viscosity. But you also get higher localized oil shearing (friction) and temperature rise at higher RPM. But the offset seems to still give increased MOFT at higher RPM.
A high volume oil pump (which also increases oil pressure) won't necessarily increase MOFT due to the actual increased pressure. But the increase in the forced flow volume through the bearings may lower the localized oil temperature inside the journal bearing, which would translate to slightly higher localized viscosity that could add some slight increase in MOFT.
Originally Posted by RDY4WAR
I should've been more clear. I wasn't referring to using a 50 or 60 grade (5.0+ cP HTHS) with tight clearances. I meant instead being forced into a 50 or 60 grade oil with wide clearances, why not instead run tighter clearances with something like a stout 20 or 30 grade. For example, a quality synthetic 10w-30 with no VIIs and an HTHS of around 3.5 cP. Would the more concentric loading of the bearing be more gentle to a lower oil grade than a less concentric pairing with the same low grade, and if so, why the continued recommendation of wide clearances for racing engines.
Ah I see what you're proposing. I'd imagine that would be a fine course of action, but may depend on the viscosity requirements of the rest of the engine. About bearings specfically, you're well covered for info here! Shannow is the guy
I should've been more clear. I wasn't referring to using a 50 or 60 grade (5.0+ cP HTHS) with tight clearances. I meant instead being forced into a 50 or 60 grade oil with wide clearances, why not instead run tighter clearances with something like a stout 20 or 30 grade. For example, a quality synthetic 10w-30 with no VIIs and an HTHS of around 3.5 cP. Would the more concentric loading of the bearing be more gentle to a lower oil grade than a less concentric pairing with the same low grade, and if so, why the continued recommendation of wide clearances for racing engines.
Ah I see what you're proposing. I'd imagine that would be a fine course of action, but may depend on the viscosity requirements of the rest of the engine. About bearings specfically, you're well covered for info here! Shannow is the guy
Also, the bearing clearance will have an effect on the MOFT with different oil viscosity. According to the graph below, the MOFT decreases with 0W-20 if the bearing clearance is over 0.002". That's why you don't want to run too thin a viscosity in large clearance bearings.
Originally Posted by ZeeOSix
Also, the bearing clearance will have an effect on the MOFT with different oil viscosity. According to the graph below, the MOFT decreases with 0W-20 if the bearing clearance is over 0.002". That's why you don't want to run too thin a viscosity in large clearance bearings.
Does this graph apply regardless of bearing/journal diameter? For example, .002" clearance on a 2" journal vs a 3" journal.
Also, the bearing clearance will have an effect on the MOFT with different oil viscosity. According to the graph below, the MOFT decreases with 0W-20 if the bearing clearance is over 0.002". That's why you don't want to run too thin a viscosity in large clearance bearings.
Does this graph apply regardless of bearing/journal diameter? For example, .002" clearance on a 2" journal vs a 3" journal.
Originally Posted by RDY4WAR
Originally Posted by ZeeOSix
Also, the bearing clearance will have an effect on the MOFT with different oil viscosity. According to the graph below, the MOFT decreases with 0W-20 if the bearing clearance is over 0.002". That's why you don't want to run too thin a viscosity in large clearance bearings.
Does this graph apply regardless of bearing/journal diameter? For example, .002" clearance on a 2" journal vs a 3" journal.
Here's the source of the info with lots of engine bearing related subjects to read if you're interested.
http://www.substech.com/dokuwiki/doku.php?id=engine_bearings
Oil Clearance and Engine Bearings
http://www.substech.com/dokuwiki/doku.php?id=oil_clearance_and_engine_bearings
Originally Posted by ZeeOSix
Also, the bearing clearance will have an effect on the MOFT with different oil viscosity. According to the graph below, the MOFT decreases with 0W-20 if the bearing clearance is over 0.002". That's why you don't want to run too thin a viscosity in large clearance bearings.
Does this graph apply regardless of bearing/journal diameter? For example, .002" clearance on a 2" journal vs a 3" journal.
Here's the source of the info with lots of engine bearing related subjects to read if you're interested.
http://www.substech.com/dokuwiki/doku.php?id=engine_bearings
Oil Clearance and Engine Bearings
http://www.substech.com/dokuwiki/doku.php?id=oil_clearance_and_engine_bearings
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