track 928 oil pressure drop?????UPDATE FILTER OPEN :>(
04-08-2009, 12:07 AM
#91
928 Collector
Rennlist Member
Rennlist Member
04-08-2009, 12:10 AM
#92
928 Collector
Rennlist Member
Rennlist Member
04-08-2009, 01:16 AM
#93
Nordschleife Master
I wouldnt bother pulling the cam covers, the flake you see will not be from the cam areas at all.
It is simply bearings you need. Well that and a drysump.
It is simply bearings you need. Well that and a drysump.
04-08-2009, 01:29 AM
#94
Rennlist Member
So, all the kidding, religion, knocking on wood, amsoil aside, why do you think i have not had any issues with my engines. Im pulling more g's, oil pressure isnt dropping and when i pull the rod bearings after years of track duty, they look fine? and its not just one engine, its 6 of them and 100s of track /race days combined. I wonder if it is luck with some tolerance of the rod bearings, or my warm up ritual. is it possible the oil is playing a part? I truely suspect that Brian's car might have had damage before hand. I dont know about the just-a-guy's history.
04-08-2009, 01:32 AM
#95
Rennlist Member
cam covers, like S4 cam covers?? or are we talking OB? no way is anything coming from the cams. the material on the cams wouldnt flake off like that.
mk
mk
04-08-2009, 01:51 AM
#96
Intermediate
Join Date: Apr 2009
Location: Maple Ridge, BC, Canada
Posts: 30
Likes: 0
Received 0 Likes
on
0 Posts
This is a NISMO (Nissan Motorsports) oil pan baffle plate for an RB26 that is installed in the sump of a GT-R oil pan for track use. It surrounds the oil pickup with trap doors that allow oil to flow in towards the pickup, but prevents it from sloshing away from the pickup due to high G forces.
This is why oiling is not generally a problem on a stock suspensioned car even if the power level remains the same - there will be less oil sitting around the pickup due to the high rpm of the oil pump, but the lateral forces in the pan won't be high enough to uncover the pickup. Add a suspension and sticky tires and your oil will no longer be sitting in your oil pan, but stuck to the side of your engine block as you pull over 1G of force on it.
In a GT-R, so much oil will end up inside the cam covers that it will literally flood right out through the breathers. That is why an oil restrictor is ALWAYS used to limit the flow to the valvetrain on any sort of performance build and most stock rebuilds even.
This is simple physics, nothing hard to understand.
1) Sustained high rpm spins your oil pump fast - pumping more oil out of your pan.
2) Oil still drains back into your pan at exactly the same rate it always does because it's relying on gravity to come back - in some instances, it's even slower as G-forces push it AWAY from the drains.
3) Just like you're straining against the harness in your car as you brake and accelerate and turn, the oil that's left in your sump is experiencing just as much force pushing it in those same directions as well.
The momentary uncovering of your pickup is what your gauge registers as a fluctuation in oil pressure. Your gauge is very slow to react compared to what is really going on and that momentary "drop" in oil pressure is really in fact a momentary LOSS of oil pressure. Your crank has probably just kissed your rod bearings. Maybe they didn't spin this time, but as evidenced by all the pictures of sparkly stuff in the filters, the bearing doesn't actually need to spin to be damaged.........
Oh, and just to top it all off, if you add ANY detonation to this mix.......... I won't even go into the age of the cars or any of the million other little factors that can all stack up and further increase the chances of failure..........
04-08-2009, 03:07 AM
#97
Three Wheelin'
A couple points...
While higher RPM will pump more oil, that doesn't mean more oil is pumped into the cylinder heads on a 928. The pressure relief valve limits the oil pressure fed to the engine and it generally remains constant from 2500-3000 on up to as fast as you want to spin it. The excess oil is dumped back into the sump. With normal operating temp oil it's about 100 psi. Cold oil will push the pressure up to 125 - 130 psi even at 2000 rpm when the secondary pressure relief valve opens. Mark Kiborts warm up procedure before any high rpm operation has a lot of merit.
The 928 cylinder heads are not supplied with dangerously too much oil at any rpm. Whether the engine is at 3000 or 6000 the oil volume is the same. There is enough oil to have a large trickle going down each drain hole and it is certainly only a small percent of the available drain hole area. Excess oil in the cylinder head is from other reasons not associated with the normal oil supply to the head.
While higher RPM will pump more oil, that doesn't mean more oil is pumped into the cylinder heads on a 928. The pressure relief valve limits the oil pressure fed to the engine and it generally remains constant from 2500-3000 on up to as fast as you want to spin it. The excess oil is dumped back into the sump. With normal operating temp oil it's about 100 psi. Cold oil will push the pressure up to 125 - 130 psi even at 2000 rpm when the secondary pressure relief valve opens. Mark Kiborts warm up procedure before any high rpm operation has a lot of merit.
The 928 cylinder heads are not supplied with dangerously too much oil at any rpm. Whether the engine is at 3000 or 6000 the oil volume is the same. There is enough oil to have a large trickle going down each drain hole and it is certainly only a small percent of the available drain hole area. Excess oil in the cylinder head is from other reasons not associated with the normal oil supply to the head.
Hi volume oil pump with sustained high revs, plus high G forces most definitely does pump your sump low enough that you will end up sucking air with your oil pickup.
This is a NISMO (Nissan Motorsports) oil pan baffle plate for an RB26 that is installed in the sump of a GT-R oil pan for track use. It surrounds the oil pickup with trap doors that allow oil to flow in towards the pickup, but prevents it from sloshing away from the pickup due to high G forces.
This is why oiling is not generally a problem on a stock suspensioned car even if the power level remains the same - there will be less oil sitting around the pickup due to the high rpm of the oil pump, but the lateral forces in the pan won't be high enough to uncover the pickup. Add a suspension and sticky tires and your oil will no longer be sitting in your oil pan, but stuck to the side of your engine block as you pull over 1G of force on it.
In a GT-R, so much oil will end up inside the cam covers that it will literally flood right out through the breathers. That is why an oil restrictor is ALWAYS used to limit the flow to the valvetrain on any sort of performance build and most stock rebuilds even.
This is simple physics, nothing hard to understand.
1) Sustained high rpm spins your oil pump fast - pumping more oil out of your pan.
2) Oil still drains back into your pan at exactly the same rate it always does because it's relying on gravity to come back - in some instances, it's even slower as G-forces push it AWAY from the drains.
3) Just like you're straining against the harness in your car as you brake and accelerate and turn, the oil that's left in your sump is experiencing just as much force pushing it in those same directions as well.
The momentary uncovering of your pickup is what your gauge registers as a fluctuation in oil pressure. Your gauge is very slow to react compared to what is really going on and that momentary "drop" in oil pressure is really in fact a momentary LOSS of oil pressure. Your crank has probably just kissed your rod bearings. Maybe they didn't spin this time, but as evidenced by all the pictures of sparkly stuff in the filters, the bearing doesn't actually need to spin to be damaged.........
Oh, and just to top it all off, if you add ANY detonation to this mix.......... I won't even go into the age of the cars or any of the million other little factors that can all stack up and further increase the chances of failure..........
This is a NISMO (Nissan Motorsports) oil pan baffle plate for an RB26 that is installed in the sump of a GT-R oil pan for track use. It surrounds the oil pickup with trap doors that allow oil to flow in towards the pickup, but prevents it from sloshing away from the pickup due to high G forces.
This is why oiling is not generally a problem on a stock suspensioned car even if the power level remains the same - there will be less oil sitting around the pickup due to the high rpm of the oil pump, but the lateral forces in the pan won't be high enough to uncover the pickup. Add a suspension and sticky tires and your oil will no longer be sitting in your oil pan, but stuck to the side of your engine block as you pull over 1G of force on it.
In a GT-R, so much oil will end up inside the cam covers that it will literally flood right out through the breathers. That is why an oil restrictor is ALWAYS used to limit the flow to the valvetrain on any sort of performance build and most stock rebuilds even.
This is simple physics, nothing hard to understand.
1) Sustained high rpm spins your oil pump fast - pumping more oil out of your pan.
2) Oil still drains back into your pan at exactly the same rate it always does because it's relying on gravity to come back - in some instances, it's even slower as G-forces push it AWAY from the drains.
3) Just like you're straining against the harness in your car as you brake and accelerate and turn, the oil that's left in your sump is experiencing just as much force pushing it in those same directions as well.
The momentary uncovering of your pickup is what your gauge registers as a fluctuation in oil pressure. Your gauge is very slow to react compared to what is really going on and that momentary "drop" in oil pressure is really in fact a momentary LOSS of oil pressure. Your crank has probably just kissed your rod bearings. Maybe they didn't spin this time, but as evidenced by all the pictures of sparkly stuff in the filters, the bearing doesn't actually need to spin to be damaged.........
Oh, and just to top it all off, if you add ANY detonation to this mix.......... I won't even go into the age of the cars or any of the million other little factors that can all stack up and further increase the chances of failure..........
04-08-2009, 03:51 AM
#98
Nordschleife Master
04-08-2009, 12:23 PM
#99
Rennlist Member
Join Date: Nov 2007
Location: Edmonton,Alberta
Posts: 1,003
Likes: 0
Received 0 Likes
on
0 Posts
I dont think its the cams either I was just going to pull the covers to inspect the cams ,cam chain and tensioner and make sure none of the flakes were pumped through the engine for what time it takes I will do it just to have a look and go from there.
Having gotten over the initial shock and thinking about it a little it should be noted that this problem occured after I went to the bigger sticker Michelin tires
Having gotten over the initial shock and thinking about it a little it should be noted that this problem occured after I went to the bigger sticker Michelin tires
04-08-2009, 01:00 PM
#100
Intermediate
Join Date: Apr 2009
Location: Maple Ridge, BC, Canada
Posts: 30
Likes: 0
Received 0 Likes
on
0 Posts
If your oil is hot (ie: poor oil cooling) it is going to pump a higher volume at any given pressure........
The common factor in these cars seems to be high traction - I'm positive they are all uncovering the pickups..........
The common factor in these cars seems to be high traction - I'm positive they are all uncovering the pickups..........
04-08-2009, 01:39 PM
#101
Rennlist Member
What are the warm up procedures you all go through?
examples:
idle for 5 min and then drive normally
just start and drive normally for 20min than hit it?
just start it, drive very easy with low rpms , and very little rpm change and very light load for 20min then hit it?
drive it normally until water temp is normal then hit it.
start and rev the engine up and down repeatetly then go? (I see this all the time at the track
)
etc.
examples:
idle for 5 min and then drive normally
just start and drive normally for 20min than hit it?
just start it, drive very easy with low rpms , and very little rpm change and very light load for 20min then hit it?
drive it normally until water temp is normal then hit it.
start and rev the engine up and down repeatetly then go? (I see this all the time at the track
)etc.
04-08-2009, 01:50 PM
#102
Rennlist Member
I have oil temp as well as stock water. they dont seem to be slow to react at all. Ive had a lot of prior issues with the thermostate area, where overheating happens relatively quickly when the block seal was compromised.
I dont think there is enough lag time to worry about at all. the only thing is that Rocket said that the oil guage might be slow to react to those momentary bubbles in pressure. That i certainly believe.
mk
I dont think there is enough lag time to worry about at all. the only thing is that Rocket said that the oil guage might be slow to react to those momentary bubbles in pressure. That i certainly believe.
mk
A little off topic; is oil temp or pressure a better/sooner indicator of problems? I assume you want both indicators. Coolant temp seemed to be a slow indicator when I blew my head gasket at the track (temp was in the lower middle part of the gauge).
I too have heard the LS1 can spin rod bearings at the track.
Tony
I too have heard the LS1 can spin rod bearings at the track.
Tony
04-08-2009, 01:54 PM
#103
Nordschleife Master
Here's something I've learned by searching the forums: For their cup-car prototype, Porsche installed the 944-2 oil pressure relief valve to the cylinder head. See http://www.norcal928.org/928cup/928CupSpecs.pdf. The part number is 944.107.139.00, or 42 in the picture in the link: http://dcauto.gotdns.com/illustration/index/438291925. Anybody with any theories what this accomplishes?
Last edited by ptuomov; 04-08-2009 at 01:57 PM. Reason: Typo in the number
04-08-2009, 02:13 PM
#105
Three Wheelin'
Here's something I've learned by searching the forums: For their cup-car prototype, Porsche installed the 944-2 oil pressure relief valve to the cylinder head. See http://www.norcal928.org/928cup/928CupSpecs.pdf. The part number is 944.107.139.00, or 42 in the picture in the link: http://dcauto.gotdns.com/illustration/index/438291925. Anybody with any theories what this accomplishes?