Notices
Series I Tech Garage The place to discuss anything technical about the RX-8 that doesn't fit into any of the categories below.

5W30 Oil Don't Cut it, Engine Bearing Pics 58K S1 RX-8 from England.

Thread Tools
 
Rate Thread
 
Old Oct 31, 2009 | 04:23 AM
  #451  
bse50's Avatar
#50
 
Joined: Nov 2007
Posts: 7,521
Likes: 11
From: Caput Mundi
So would the pressure regulator be a good idea for the ones that are mad enough to often see high load\high rpms?

Where are you in the uk?
Reply
Old Oct 31, 2009 | 10:15 AM
  #452  
olddragger's Avatar
Registered
iTrader: (3)
 
Joined: Apr 2004
Posts: 10,828
Likes: 40
From: macon, georgia
anyone use marvel mystery oil for premix---thread jack--sorry?
OD
Reply
Old Oct 31, 2009 | 10:49 AM
  #453  
9krpmrx8's Avatar
SARX Legend
iTrader: (46)
 
Joined: Jan 2007
Posts: 33,788
Likes: 462
From: San Antonio, Texas
TX

Originally Posted by olddragger
anyone use marvel mystery oil for premix---thread jack--sorry?
OD
I think Swoope is. FYI, it's only $2.50 at the dollar store.
Reply
Old Oct 31, 2009 | 12:17 PM
  #454  
@!!narotordo's Avatar
FLAME ON!
 
Joined: Jul 2009
Posts: 948
Likes: 0
From: Strip Club
^Or was.
Reply
Old Oct 31, 2009 | 12:38 PM
  #455  
@!!narotordo's Avatar
FLAME ON!
 
Joined: Jul 2009
Posts: 948
Likes: 0
From: Strip Club
Lightbulb

Originally Posted by TZ250
This is a great question. What is the temp of the oil as it flows through the bearings, compared to indicated temp? I believe the mid range viscosities flow more quickly and draw the heat off much more efficiently than the highest weight viscosities. One man's opinion.
Good point!
Reply
Old Oct 31, 2009 | 07:16 PM
  #456  
madcows's Avatar
Registered User
 
Joined: Apr 2009
Posts: 239
Likes: 0
From: michigan
Originally Posted by PhillipM
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!
Reply
Old Oct 31, 2009 | 07:57 PM
  #457  
TZ250's Avatar
Registered User
 
Joined: Aug 2009
Posts: 98
Likes: 0
From: Northwest
Originally Posted by PhillipM
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.
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?
Reply
Old Oct 31, 2009 | 08:41 PM
  #458  
PhillipM's Avatar
Registered
 
Joined: Dec 2007
Posts: 863
Likes: 0
From: UK
Originally Posted by TZ250
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?
Not quite right, as it's an orifice, twice the pressure will actually equal slightly less than twice the flow, same with the seperation, at twice the pressure, you experience fast flow loss through the bearing and more power loss = slightly less than double.
Reply
Old Oct 31, 2009 | 09:01 PM
  #459  
madcows's Avatar
Registered User
 
Joined: Apr 2009
Posts: 239
Likes: 0
From: michigan
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?
Reply
Old Oct 31, 2009 | 09:18 PM
  #460  
PhillipM's Avatar
Registered
 
Joined: Dec 2007
Posts: 863
Likes: 0
From: UK
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.
Reply
Old Oct 31, 2009 | 09:28 PM
  #461  
TZ250's Avatar
Registered User
 
Joined: Aug 2009
Posts: 98
Likes: 0
From: Northwest
Originally Posted by PhillipM
Not quite right, as it's an orifice, twice the pressure will actually equal slightly less than twice the flow, same with the seperation, at twice the pressure, you experience fast flow loss through the bearing and more power loss = slightly less than double.
Shocking that I was that close to being right. I'm chuffed. Are you a fluid dynamics engineer?
Reply
Old Oct 31, 2009 | 10:39 PM
  #462  
olddragger's Avatar
Registered
iTrader: (3)
 
Joined: Apr 2004
Posts: 10,828
Likes: 40
From: macon, georgia
if hes not he should be.
OD
Reply
Old Nov 1, 2009 | 08:55 AM
  #463  
PhillipM's Avatar
Registered
 
Joined: Dec 2007
Posts: 863
Likes: 0
From: UK
Originally Posted by TZ250
Shocking that I was that close to being right. I'm chuffed. Are you a fluid dynamics engineer?
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!
Reply
Old Nov 1, 2009 | 04:49 PM
  #464  
olddragger's Avatar
Registered
iTrader: (3)
 
Joined: Apr 2004
Posts: 10,828
Likes: 40
From: macon, georgia
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

Last edited by olddragger; Nov 1, 2009 at 04:52 PM.
Reply
Old Nov 1, 2009 | 07:39 PM
  #465  
9krpmrx8's Avatar
SARX Legend
iTrader: (46)
 
Joined: Jan 2007
Posts: 33,788
Likes: 462
From: San Antonio, Texas
Those number are inline with mine.
Reply
Old Nov 2, 2009 | 07:49 AM
  #466  
Mazmart's Avatar
Registered
iTrader: (12)
 
Joined: Mar 2004
Posts: 4,794
Likes: 67
Originally Posted by olddragger
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
Are you suggesting that you believe you have a problem?

Paul.
Reply
Old Nov 2, 2009 | 09:09 AM
  #467  
olddragger's Avatar
Registered
iTrader: (3)
 
Joined: Apr 2004
Posts: 10,828
Likes: 40
From: macon, georgia
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
Reply
Old Nov 2, 2009 | 10:06 AM
  #468  
ayrton012's Avatar
Ayrton Senna Forever
 
Joined: Sep 2005
Posts: 406
Likes: 1
From: Europe
Originally Posted by olddragger
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
1.I have the same max pressure with 30w (0w-30), as it is normal. So there has to be a limiter with 71 PSI ( as Ash attached), but where, if according to Mr Engman and Paul there are only an emergency first relief valve (about 156PSI), and the rear relief valve with 78-91 PSI value. I'm confused.


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)
Reply
Old Nov 2, 2009 | 10:39 AM
  #469  
Mazmart's Avatar
Registered
iTrader: (12)
 
Joined: Mar 2004
Posts: 4,794
Likes: 67
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.
Reply
Old Nov 2, 2009 | 11:18 AM
  #470  
olddragger's Avatar
Registered
iTrader: (3)
 
Joined: Apr 2004
Posts: 10,828
Likes: 40
From: macon, georgia
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!
Reply
Old Nov 2, 2009 | 05:43 PM
  #471  
9krpmrx8's Avatar
SARX Legend
iTrader: (46)
 
Joined: Jan 2007
Posts: 33,788
Likes: 462
From: San Antonio, Texas
Ouch.



Reply
Old Nov 2, 2009 | 08:17 PM
  #472  
HockeyRX-8's Avatar
TNC
iTrader: (1)
 
Joined: Feb 2008
Posts: 3,858
Likes: 0
From: Shaolin, NY
....that's some bad wear...
Reply
Old Nov 2, 2009 | 09:39 PM
  #473  
nycgps's Avatar
Out of NYC
iTrader: (1)
 
Joined: Jun 2005
Posts: 19,881
Likes: 36
From: Planet Earth
Originally Posted by 9krpmrx8
Ouch.



did u found that engine at a dumpster or something?

running without filter?

anyway, ouch
Reply
Old Nov 2, 2009 | 11:53 PM
  #474  
9krpmrx8's Avatar
SARX Legend
iTrader: (46)
 
Joined: Jan 2007
Posts: 33,788
Likes: 462
From: San Antonio, Texas
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/

Last edited by 9krpmrx8; Nov 2, 2009 at 11:59 PM.
Reply
Old Nov 3, 2009 | 02:09 AM
  #475  
bse50's Avatar
#50
 
Joined: Nov 2007
Posts: 7,521
Likes: 11
From: Caput Mundi
Originally Posted by 9krpmrx8
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/
Uhm... that doesn't look like an oil viscosity problem
More infos on the engine?
Reply


You have already rated this thread Rating: Thread Rating: 0 votes,  average.


All times are GMT -5. The time now is 01:05 AM.