5W30 Oil Don't Cut it, Engine Bearing Pics 58K S1 RX-8 from England.
10-31-2009, 12:38 PM
#455
FLAME ON!
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Good point!
10-31-2009, 07:16 PM
#456
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There's pressure exerted from the centripetal force generated by the stroke of the rotor too, that increases at the square of the engine speed, so more rpms = massive jump in stress, and because the surface speed differential on the bearing is higher at high rpm, it slings oil out of the bearing faster from the hydrodynamic wave traveling in front of the bearing oscillation, which is also why you need more flow for higher RPMs.
Thank you for the explanation, sir!
10-31-2009, 07:57 PM
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There's pressure exerted from the centripetal force generated by the stroke of the rotor too, that increases at the square of the engine speed, so more rpms = massive jump in stress, and because the surface speed differential on the bearing is higher at high rpm, it slings oil out of the bearing faster from the hydrodynamic wave traveling in front of the bearing oscillation, which is also why you need more flow for higher RPMs.
10-31-2009, 08:41 PM
#458
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It is my understanding that separation presssure, or the force applied by the oil film to keep the bearing surfaces from touching, increases in direct linear proportion to flow. In other words, doubling the flow of the same oil at the same temperature doubles the separation pressure within the babbit/journal. Doubling of pressure, same oil, same temp, also has a direct linear effect on flow: twice the pressure, twice the flow. Comments?
10-31-2009, 09:01 PM
#459
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Phillip, then what parameters do we need to know (bearing orifice size, total surface area of rotor bearing, etc) in order to determine what the ideal pressure would be for a given RPM, oil viscosity and temp?
Also, do you think an increase in oil flow rate on a renesis would be beneficial for any reasons other than oil/engine cooling?
Also, do you think an increase in oil flow rate on a renesis would be beneficial for any reasons other than oil/engine cooling?
10-31-2009, 09:18 PM
#460
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To be honest, without proper modelling software, or a long time sat working things out with some imperical testing, you could only get a rough rule of thumb, even the best modelling and CFD software can't give you a perfect figure.
10-31-2009, 09:28 PM
#461
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Shocking that I was that close to being right. I'm chuffed. Are you a fluid dynamics engineer?
11-01-2009, 08:55 AM
#463
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No, but as I said, reworking and redesigning dampers is part of my job, so there's a fair bit of fluid dynamics involved, but I won't pretend I know anywhere near enough on the subject!
11-01-2009, 04:49 PM
#464
ok oil pressure gauge installed
I run diesel oil
was unable to get the oil temps over 175f with moderate spirited driving (my redline is 7.5--8K)
ambient temps 62F
my idle is at 1.2K
oil pressure on start up---80psi (warm up rpm 2K)
at 175F----30psi
3K rpm @ 175F =58psi
4k rpm @ 175F =71psi
6.7K rpm @ 175F = 80
Car does not go above 80psi with my diesel oil regardless of rpm.
So from 6.7K to 8K no change in oil pressure
Now to see how the 09 compares---someone?
Higher rpms may be the weak area of flow? And maybe there is a lot of oil dumping into the pan causing some problems? Foaming/ air captivation? Another reason for the 09 baffles etc.?.
oildrragger
I run diesel oil
was unable to get the oil temps over 175f with moderate spirited driving (my redline is 7.5--8K)
ambient temps 62F
my idle is at 1.2K
oil pressure on start up---80psi (warm up rpm 2K)
at 175F----30psi
3K rpm @ 175F =58psi
4k rpm @ 175F =71psi
6.7K rpm @ 175F = 80
Car does not go above 80psi with my diesel oil regardless of rpm.
So from 6.7K to 8K no change in oil pressure
Now to see how the 09 compares---someone?
Higher rpms may be the weak area of flow? And maybe there is a lot of oil dumping into the pan causing some problems? Foaming/ air captivation? Another reason for the 09 baffles etc.?.
oildrragger
Last edited by olddragger; 11-01-2009 at 04:52 PM.
11-02-2009, 07:49 AM
#466
ok oil pressure gauge installed
I run diesel oil
was unable to get the oil temps over 175f with moderate spirited driving (my redline is 7.5--8K)
ambient temps 62F
my idle is at 1.2K
oil pressure on start up---80psi (warm up rpm 2K)
at 175F----30psi
3K rpm @ 175F =58psi
4k rpm @ 175F =71psi
6.7K rpm @ 175F = 80
Car does not go above 80psi with my diesel oil regardless of rpm.
So from 6.7K to 8K no change in oil pressure
Now to see how the 09 compares---someone?
Higher rpms may be the weak area of flow? And maybe there is a lot of oil dumping into the pan causing some problems? Foaming/ air captivation? Another reason for the 09 baffles etc.?.
oildrragger
I run diesel oil
was unable to get the oil temps over 175f with moderate spirited driving (my redline is 7.5--8K)
ambient temps 62F
my idle is at 1.2K
oil pressure on start up---80psi (warm up rpm 2K)
at 175F----30psi
3K rpm @ 175F =58psi
4k rpm @ 175F =71psi
6.7K rpm @ 175F = 80
Car does not go above 80psi with my diesel oil regardless of rpm.
So from 6.7K to 8K no change in oil pressure
Now to see how the 09 compares---someone?
Higher rpms may be the weak area of flow? And maybe there is a lot of oil dumping into the pan causing some problems? Foaming/ air captivation? Another reason for the 09 baffles etc.?.
oildrragger
Paul.
11-02-2009, 09:09 AM
#467
Trying to make me think aren't you!, You know that makes my head hurt.
Problem?---I am not sure. But, do remember these readings are with a 40wgt oil and a temp of only 175F. I wonder want is happening at 210F?
I think a bypass is opening --I can see this occuring at cold start. Innitial pressure is 80psi but in just a few seconds the pressure does drop to 72-74psi.
I also think the pump has the capicity to drive a higher oil pressure evidenced by the relief valve opening at 74psi but the pressure continues to climb a little.
I am a little concerned that there is no increase in the pressure from 6.7K forward.
I am also questioning why such a high oil pressure at cold start? Is it really that much more resistance from the oil at cold start of 72F versus the 175F? If it continues on a linear scale then another--say 50 degrees (oil at 225) wouldnt the pressures be substantually affected? We would probably have a very low idle pressure.
I do like the 09 oil pan baffles and pick up.
See I told you--now I have a headache.
olddragger
Problem?---I am not sure. But, do remember these readings are with a 40wgt oil and a temp of only 175F. I wonder want is happening at 210F?
I think a bypass is opening --I can see this occuring at cold start. Innitial pressure is 80psi but in just a few seconds the pressure does drop to 72-74psi.
I also think the pump has the capicity to drive a higher oil pressure evidenced by the relief valve opening at 74psi but the pressure continues to climb a little.
I am a little concerned that there is no increase in the pressure from 6.7K forward.
I am also questioning why such a high oil pressure at cold start? Is it really that much more resistance from the oil at cold start of 72F versus the 175F? If it continues on a linear scale then another--say 50 degrees (oil at 225) wouldnt the pressures be substantually affected? We would probably have a very low idle pressure.
I do like the 09 oil pan baffles and pick up.
See I told you--now I have a headache.
olddragger
11-02-2009, 10:06 AM
#468
Ayrton Senna Forever
Trying to make me think aren't you!, You know that makes my head hurt.
Problem?---I am not sure. But, do remember these readings are with a 40wgt oil and a temp of only 175F. I wonder want is happening at 210F?
I think a bypass is opening --I can see this occuring at cold start. Innitial pressure is 80psi but in just a few seconds the pressure does drop to 72-74psi.
I also think the pump has the capicity to drive a higher oil pressure evidenced by the relief valve opening at 74psi but the pressure continues to climb a little.
I am a little concerned that there is no increase in the pressure from 6.7K forward.
I am also questioning why such a high oil pressure at cold start? Is it really that much more resistance from the oil at cold start of 72F versus the 175F? If it continues on a linear scale then another--say 50 degrees (oil at 225) wouldnt the pressures be substantually affected? We would probably have a very low idle pressure.
I do like the 09 oil pan baffles and pick up.
See I told you--now I have a headache.
olddragger
Problem?---I am not sure. But, do remember these readings are with a 40wgt oil and a temp of only 175F. I wonder want is happening at 210F?
I think a bypass is opening --I can see this occuring at cold start. Innitial pressure is 80psi but in just a few seconds the pressure does drop to 72-74psi.
I also think the pump has the capicity to drive a higher oil pressure evidenced by the relief valve opening at 74psi but the pressure continues to climb a little.
I am a little concerned that there is no increase in the pressure from 6.7K forward.
I am also questioning why such a high oil pressure at cold start? Is it really that much more resistance from the oil at cold start of 72F versus the 175F? If it continues on a linear scale then another--say 50 degrees (oil at 225) wouldnt the pressures be substantually affected? We would probably have a very low idle pressure.
I do like the 09 oil pan baffles and pick up.
See I told you--now I have a headache.
olddragger
2. Yes the cold oil resistance is horrible high vs hot oil (even 0w). ...and we have this high pressure with opened e-shaft pellet (under 60C)
11-02-2009, 10:39 AM
#469
Seems to me that everything is fine pressurewise, as it tends to be with rotary engines. Some increase from this is not a bad thing (If you need it and can use it) but we don't need to re-invent the wheel or conduct every test that Mazda has done already. The chosen viscosity is where I have a problem and Mazda has expressed the reasons for their choice and it's no different than any other modern manufacturer: They must achieve better CAFE numbers and every little bit counts.
So, again, one more time: These engines are not starving for oil at startup nor are they running a deficiency of pressure in everyday useage.
Paul.
So, again, one more time: These engines are not starving for oil at startup nor are they running a deficiency of pressure in everyday useage.
Paul.
11-02-2009, 11:18 AM
#470
How about when you go with forced induction and track? Thats me.
I think if it will work out then the updated oil pan would not hurt and since the pan is off why not bump the pressure up a tad?
Besides I need to buy something else from you anyway. I just enjoy the experience.
By the way my engine idles with 21 of vacuum----thank you very much!
I think if it will work out then the updated oil pan would not hurt and since the pan is off why not bump the pressure up a tad?
Besides I need to buy something else from you anyway. I just enjoy the experience.
By the way my engine idles with 21 of vacuum----thank you very much!
....that's some bad wear...
11-02-2009, 11:53 PM
#474
SARX Legend
iTrader: (46)
It's a local member here that is rebuilding his engine.
Ran 10W-40, 70k on the motor. Front Apex seal was ****, says the rear was perfect.
http://www.flickr.com/photos/8253620...th/4067199003/
Ran 10W-40, 70k on the motor. Front Apex seal was ****, says the rear was perfect.
http://www.flickr.com/photos/8253620...th/4067199003/
Last edited by 9krpmrx8; 11-02-2009 at 11:59 PM.
11-03-2009, 02:09 AM
#475
It's a local member here that is rebuilding his engine.
Ran 10W-40, 70k on the motor. Front Apex seal was ****, says the rear was perfect.
http://www.flickr.com/photos/8253620...th/4067199003/
Ran 10W-40, 70k on the motor. Front Apex seal was ****, says the rear was perfect.
http://www.flickr.com/photos/8253620...th/4067199003/
More infos on the engine?