Oil starvation problem at high rpm
10-17-2003, 01:08 PM
#46
Thanks for the info Marc. When you say "Scavenger pump manifold", what exactly are you referring to? Some sort of multiple connection pipe which resides on the oil pan so that the scavenge system can get all the oil?
When you say "pumps", what area would you be speaking of? A pump to carry oil from the scavenge to the tank? Wouldn't the scavenge do that?
When you say "pumps", what area would you be speaking of? A pump to carry oil from the scavenge to the tank? Wouldn't the scavenge do that?
10-17-2003, 04:17 PM
#47
10-17-2003, 04:53 PM
#48
Rennlist Member
Hallet, you mean a slow buttonwillow of the midwest?? I dont think so. However, there is a reason you havent seen me at Willow springs lately with the un-sumped Holbert car!!
However, again, Sears has the carocell, Thunderhill has turn 2 , Laguna has the high rpm 3rd gear turn 9 sweeper. If it was going to blow, I would think it would have happened at T-hill on turn 2!!
MK
However, again, Sears has the carocell, Thunderhill has turn 2 , Laguna has the high rpm 3rd gear turn 9 sweeper. If it was going to blow, I would think it would have happened at T-hill on turn 2!!
MK
Originally posted by Tony
eh...you'll blow it up at Hallet Kibort, trying to keep up with everyone!
eh...you'll blow it up at Hallet Kibort, trying to keep up with everyone!
10-17-2003, 04:59 PM
#49
Rennlist Member
someone needs to tell us if the pressure changes with Mobil 1 going to redline or amzoil 20-50. so far, sure, accusump is part of the solution, but from what I have seen, the oil brand is part of the issue! very scarry to see the oil pressure warning light come on with a hot , raced engine on Mobil 1. never even close to this in either race car S2 or S4 with Amzoil, even during SpeedWorld challeng 1 hour races at laguna. we have the video tape that shows the oil pressure guage on both cars. no fluctuation. Devek saw fluctuation of 2 bar, and was using mobil 1. coincidence??? lets investigate!!
MK
MK
MK
MK
10-17-2003, 05:11 PM
#50
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Funny thig is: We have an acoustic signeal when we leave the key in the ignition, or leave the lights on, but not when the oil pressure drops. Some electronic guru should be able to design a buzzer that goes off when the pressure drops at high rpm - not as a solution to the problem, but a way to help the driver prevent the worst...
Last edited by Nicole; 10-30-2003 at 07:54 AM.
10-17-2003, 06:12 PM
#51
Rennlist Member
I dont think it has to get to 0pressure to become an issue, even for several seconds. what Marc is talking about a visible change in pressure (i think he said 2-3 bar, on a high G turn) could be pointing to an indication that there may be lapses in the oil flow to 2-6 bearing. (even though the guage is showing some pressure.
I had a fiat that lost an oil pump and remember driving for awhile in denial.
I think the RPMs are a big factor, as well as the film strength and type of oil used. Again, I still think mobil 1 is the problem. Just because porsche recommends it (so what, there was a business deal with porsche and mobil, does that mean its the best oil? certainly not!! if you understand how these negotiations go) Race proven in my book , is the proof I look for as well as those wear scar tests!!!
waiting for the mobil 1 vs redline/amzoil hot oil pressure comparison from a few of your that know who you are!!
mk
I had a fiat that lost an oil pump and remember driving for awhile in denial.
I think the RPMs are a big factor, as well as the film strength and type of oil used. Again, I still think mobil 1 is the problem. Just because porsche recommends it (so what, there was a business deal with porsche and mobil, does that mean its the best oil? certainly not!! if you understand how these negotiations go) Race proven in my book , is the proof I look for as well as those wear scar tests!!!
waiting for the mobil 1 vs redline/amzoil hot oil pressure comparison from a few of your that know who you are!!
mk
Originally posted by Nicole
Funny thig is: We have an acoustic signeal when we leavle the key in the ignition, or leave the lights on, but not when the oil pressure drops. Some electronic guru should be able to design a buzzer that goes off when the pressure drops at high rpm - not as a solution to the problem, but a way to help the driver prevent the worst...
Funny thig is: We have an acoustic signeal when we leavle the key in the ignition, or leave the lights on, but not when the oil pressure drops. Some electronic guru should be able to design a buzzer that goes off when the pressure drops at high rpm - not as a solution to the problem, but a way to help the driver prevent the worst...
10-17-2003, 07:04 PM
#52
Track Day
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Hi Marc,
....................................................................
Nicole: Tell Uli to say hi to Riener for us!!
...................................................................
OK,.....
Uli
....................................................................
Nicole: Tell Uli to say hi to Riener for us!!
...................................................................
OK,.....
Uli
10-17-2003, 09:29 PM
#53
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Hi,
Mark Kibort - yes, as Castrol once advertised "oils ain't oils"!
Some people still get confused with the oil pressure/oil flow equation
and viscosity too
It is a pity that Marc@DEVEK did not fully answer my previous questions on this thread
Really credible and meaningful data may eventually lead to a balanced conclusion here and a "suitable fix" that we all can share
The formulation of readily available engine oils, either synthetic or mineral, do not always enable them to perform in an unintended application - like racing! M1 in the lower viscosities at least is probably one of these along with many other oil brands/types/viscosities
The selection of a racing oil is a specialised process on its own and for instance the M1 or Castrol etc. formulation we can buy locally may be and usually is a long way from that used in a car displaying M1 or Castrol etc. signs and racing at Le Mans or elsewhere in a sponsored team. We all know that anyway!
No oil will make up for an inherent engine design fault either. They are formulated to meet a specific and universally agreed design criteria, and generally this is for normal use as agreed by the engine and oil makers - and warranty binding
They can be and are especially formulated for a gearbox/transmission design shortfall - often on an individual manufacturer basis - and warranty binding
The real problem with oils under operational stress is their ability to maintain a suitably durable film strength at high temperatures and under high load. And as well their ability to maintain viscosity under a continuous shear cycle is critical - this is now being measured too. Their High Temperature/High Stress ( HT/HS ) ability is a specific design criteria and the European A3 Rating ( and B3 too, preferably ) is the one(s) we want to see on our oil containers
This viscosity rating is 3.5 cSt at 150C. Many readily available oils meet this including some with a low viscosity. Some significantly exceed it and these are the oils that should be considered for racing purposes - most are in the higher viscosity ranges.
Unless suitably "fortified", low viscosity oils are simply not suitable for sustained high oil temperatures and high loads
Castrol at one stage recommended synthetic grades of 0w30 or 10w-60 for 928s used in "Club Days" or "Racing". It is noted that the 0w-30 is no longer sold in this Country but the 10w-60 is still readily available
It is probably a case of "the higher HT/HS viscosity the better" all else being equal. Synthetic racing oils using Esters and perhaps other special additives may exceed this by a substantial margin. Some high grade diesel engine oils that are suitable for a 928 engine have a HT/HS rating beyond 3.5 cSt too
Along wih the HT/HS rating the oil's flash point is significant too as it's volatility as these may have a bearing on oil consumption at high temperatures. Excessive fuel dilution exacerbates this issue too
We cannot readily purchase Redline or Amsoil oils in Australia so I am not familiar with them. For racing use these may well be suitable. For normal use some of them allegedly "meet" the API or ACEA Ratings but may not be "Approved". This difference may be significant for day to day use in a 928 and is probably less so when racing
European specialised oil producer MOTUL's 300V is a racing specific oil with a great reputation It is probably not suitable for day to day use ( they do make others that are ).
I believe 300V is available in NA - it is certainly available here in Australia. This oil is made in various viscosities up to a 15w-60 ( note the Castrol viscosity mentioned earlier) which was developed for long distance racing where fuel dilution is a problem. This ester based product is good for turbocharged engines as they tend not to leave coking deposits
Some high quality synthetic diesel engine ( fleet ) oils with a petrol engine rating ( CI/SL ) like Mobil's Delvac 1 5w-40 could be tried too. This oil has a HT/HS viscosity of 4.1 and tends to hold viscosity extremely well when under stress for long periods. This has been my extended experience with this oil which is now in my 928 ( along with many other very expensive engines I own )
If more "credible" data can be made available some research may suggest a preferred oil brand/type/viscosity range for use in racing a 928.
No hype, "no religion" just that facts!
I hope this helps a bit
Mark Kibort - yes, as Castrol once advertised "oils ain't oils"!
Some people still get confused with the oil pressure/oil flow equation
and viscosity too
It is a pity that Marc@DEVEK did not fully answer my previous questions on this thread
Really credible and meaningful data may eventually lead to a balanced conclusion here and a "suitable fix" that we all can share
The formulation of readily available engine oils, either synthetic or mineral, do not always enable them to perform in an unintended application - like racing! M1 in the lower viscosities at least is probably one of these along with many other oil brands/types/viscosities
The selection of a racing oil is a specialised process on its own and for instance the M1 or Castrol etc. formulation we can buy locally may be and usually is a long way from that used in a car displaying M1 or Castrol etc. signs and racing at Le Mans or elsewhere in a sponsored team. We all know that anyway!
No oil will make up for an inherent engine design fault either. They are formulated to meet a specific and universally agreed design criteria, and generally this is for normal use as agreed by the engine and oil makers - and warranty binding
They can be and are especially formulated for a gearbox/transmission design shortfall - often on an individual manufacturer basis - and warranty binding
The real problem with oils under operational stress is their ability to maintain a suitably durable film strength at high temperatures and under high load. And as well their ability to maintain viscosity under a continuous shear cycle is critical - this is now being measured too. Their High Temperature/High Stress ( HT/HS ) ability is a specific design criteria and the European A3 Rating ( and B3 too, preferably ) is the one(s) we want to see on our oil containers
This viscosity rating is 3.5 cSt at 150C. Many readily available oils meet this including some with a low viscosity. Some significantly exceed it and these are the oils that should be considered for racing purposes - most are in the higher viscosity ranges.
Unless suitably "fortified", low viscosity oils are simply not suitable for sustained high oil temperatures and high loads
Castrol at one stage recommended synthetic grades of 0w30 or 10w-60 for 928s used in "Club Days" or "Racing". It is noted that the 0w-30 is no longer sold in this Country but the 10w-60 is still readily available
It is probably a case of "the higher HT/HS viscosity the better" all else being equal. Synthetic racing oils using Esters and perhaps other special additives may exceed this by a substantial margin. Some high grade diesel engine oils that are suitable for a 928 engine have a HT/HS rating beyond 3.5 cSt too
Along wih the HT/HS rating the oil's flash point is significant too as it's volatility as these may have a bearing on oil consumption at high temperatures. Excessive fuel dilution exacerbates this issue too
We cannot readily purchase Redline or Amsoil oils in Australia so I am not familiar with them. For racing use these may well be suitable. For normal use some of them allegedly "meet" the API or ACEA Ratings but may not be "Approved". This difference may be significant for day to day use in a 928 and is probably less so when racing
European specialised oil producer MOTUL's 300V is a racing specific oil with a great reputation It is probably not suitable for day to day use ( they do make others that are ).
I believe 300V is available in NA - it is certainly available here in Australia. This oil is made in various viscosities up to a 15w-60 ( note the Castrol viscosity mentioned earlier) which was developed for long distance racing where fuel dilution is a problem. This ester based product is good for turbocharged engines as they tend not to leave coking deposits
Some high quality synthetic diesel engine ( fleet ) oils with a petrol engine rating ( CI/SL ) like Mobil's Delvac 1 5w-40 could be tried too. This oil has a HT/HS viscosity of 4.1 and tends to hold viscosity extremely well when under stress for long periods. This has been my extended experience with this oil which is now in my 928 ( along with many other very expensive engines I own )
If more "credible" data can be made available some research may suggest a preferred oil brand/type/viscosity range for use in racing a 928.
No hype, "no religion" just that facts!
I hope this helps a bit
10-29-2003, 11:56 AM
#54
Race Director
Hmm
Since 944 motors are very similer to 928 motors I had read this thread with interest.
What are the best ways to reduce #2 rod bearing failures on 944 NA's?
1) Use AMSOil or Redline?
2) Use stock redline (6400 rpm) and shft about 6000?
3) Baffle oil pan?
4) Accusump?
5) Drill Crank?
6) Dry Sump? (not sure if I has been done for 944 motors)
7) restrict oil flow to heads?
Since 944 motors are very similer to 928 motors I had read this thread with interest.
What are the best ways to reduce #2 rod bearing failures on 944 NA's?
1) Use AMSOil or Redline?
2) Use stock redline (6400 rpm) and shft about 6000?
3) Baffle oil pan?
4) Accusump?
5) Drill Crank?
6) Dry Sump? (not sure if I has been done for 944 motors)
7) restrict oil flow to heads?
10-29-2003, 12:41 PM
#55
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I just saw this thread as well. Sparked my interest because I know a 928 GTS owner who had this #2/6 failure. Anybody here know Gary Grigsby? He used to race his GTS, but now runs a white 968. He told me when he was running big 18" Hooisers on his GTS it was just too much mechanical grip and the bearings spun. Replacement crank was a ridiculous amount of $$
I agree with Mark about Mobil 1. The "on track" oil pressure difference in my 944 turbo between 15/50 M1 and 20/50 Redline is amazing. A local shop here also told me Redline happens to run many degrees cooler. I haven't had any problems on track to speak of, all I do is overfill the tank with 20/50 Redline and shift just after 6k. 139k miles on my bottom end right now
I agree with Mark about Mobil 1. The "on track" oil pressure difference in my 944 turbo between 15/50 M1 and 20/50 Redline is amazing. A local shop here also told me Redline happens to run many degrees cooler. I haven't had any problems on track to speak of, all I do is overfill the tank with 20/50 Redline and shift just after 6k. 139k miles on my bottom end right now
10-29-2003, 01:46 PM
#56
Racer
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My first pic. of 928 oil ways in the crank.
This is Rods 1 & 5 fed from Mains No. 1
Rods 2 & 6 are exactly the same except fed from Mains no 2
This shows where the 'up-hill'/ 'against centrifugal force' theory comes from
(not mine)
PS. Anybody know how to get the oilway plugs out ? they appear to be pressed in & then peened over ?
This is Rods 1 & 5 fed from Mains No. 1
Rods 2 & 6 are exactly the same except fed from Mains no 2
This shows where the 'up-hill'/ 'against centrifugal force' theory comes from
(not mine)
PS. Anybody know how to get the oilway plugs out ? they appear to be pressed in & then peened over ?
10-29-2003, 01:57 PM
#58
Nordschleife Master
Originally posted by M758
Hmm
Since 944 motors are very similer to 928 motors I had read this thread with interest.
What are the best ways to reduce #2 rod bearing failures on 944 NA's?
1) Use AMSOil or Redline?
2) Use stock redline (6400 rpm) and shft about 6000?
3) Baffle oil pan?
4) Accusump?
5) Drill Crank?
6) Dry Sump? (not sure if I has been done for 944 motors)
7) restrict oil flow to heads?
Hmm
Since 944 motors are very similer to 928 motors I had read this thread with interest.
What are the best ways to reduce #2 rod bearing failures on 944 NA's?
1) Use AMSOil or Redline?
2) Use stock redline (6400 rpm) and shft about 6000?
3) Baffle oil pan?
4) Accusump?
5) Drill Crank?
6) Dry Sump? (not sure if I has been done for 944 motors)
7) restrict oil flow to heads?
use a synthetic oil, cross drill crank, and drysump, I am positive drysump has been done, if not, good time to start,
