track 928 oil pressure drop?????UPDATE FILTER OPEN :>(
04-05-2009, 06:02 PM
#1
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track 928 oil pressure drop?????UPDATE FILTER OPEN :>(
As expected I've noticed an oil pressure drop in the Widow in left hand turns (right too when hot)....in the 1st laps of a session when the oil is cooler (I don't have a temp gauge) the pressure typically drops to 4 bar in turn 2 (sweeping left hander)...but as I increase the pace & G loads the pressure will drop to 2-2.5bar in the final laps of the session.....
So how low is too low? I take this corner in 3rd gear between 4-5k rpm...typically exit over 5k at WOT when the pressure is lowest...as soon as the car straightens out the pressure spikes back up to 5+bar.....but as soon as I turn again it instantly drops to 3 bar.....
At the end of the sessions the oil is hot enough when I come in the pits I get the usual lifter tick for a little bit until things cool down.....water temp never goes over the 2nd white line or about 195F..typical on track water temps are between 1/2-to just under 2nd white line so say 180-190F
I'm using Amsoil racing 15-50 with a 100% stock S4 oiling system including the factory cooler in the upgraded C&R radiator....
In an ideal world a drysump would solve everything....but it costs at least $3k....I'm thinking installing an oil cooler in the fender will increase capacity and bring oil temps down which should help.....but maybe an accusump with the EPC valve is another good option...however the pressure settings of the EPC valve are either a bit too low 35-40psi (2.4-2.7 bar) or a bit too high 55-60psi (3.7-4.0 bar).....
many 928 racers have used accusumps with good success...& I know of only 1 that had a rod bearing failure after many track days..... of course the dry sumps work really well too....
So how low is too low? I take this corner in 3rd gear between 4-5k rpm...typically exit over 5k at WOT when the pressure is lowest...as soon as the car straightens out the pressure spikes back up to 5+bar.....but as soon as I turn again it instantly drops to 3 bar.....
At the end of the sessions the oil is hot enough when I come in the pits I get the usual lifter tick for a little bit until things cool down.....water temp never goes over the 2nd white line or about 195F..typical on track water temps are between 1/2-to just under 2nd white line so say 180-190F
I'm using Amsoil racing 15-50 with a 100% stock S4 oiling system including the factory cooler in the upgraded C&R radiator....
In an ideal world a drysump would solve everything....but it costs at least $3k....I'm thinking installing an oil cooler in the fender will increase capacity and bring oil temps down which should help.....but maybe an accusump with the EPC valve is another good option...however the pressure settings of the EPC valve are either a bit too low 35-40psi (2.4-2.7 bar) or a bit too high 55-60psi (3.7-4.0 bar).....
many 928 racers have used accusumps with good success...& I know of only 1 that had a rod bearing failure after many track days..... of course the dry sumps work really well too....
Last edited by IcemanG17; 04-06-2009 at 08:06 PM.
04-05-2009, 06:25 PM
#2
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Someone has to ask: What kind of oil / weight?
IMO it's a bad idea to run a 928 on the track with any seriousness without moving the oil cooler out of the radiator and adding an accusump.*
Assuming your gauge is accurate, anything lower than 4 bar would scare me.
I would also add an oil temp gauge with a data logger ASAP.
*Unless your initials are M.K.
IMO it's a bad idea to run a 928 on the track with any seriousness without moving the oil cooler out of the radiator and adding an accusump.*
Assuming your gauge is accurate, anything lower than 4 bar would scare me.
I would also add an oil temp gauge with a data logger ASAP.
*Unless your initials are M.K.
04-05-2009, 06:59 PM
#3
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You better get that "special Amsoil" Kibort uses!
If it was my track car, there would be at least an accusump plumbed into the system. Probably check 2/6 rod bearings at the end of the season too. Cheaper than a rebuild.
Jim
If it was my track car, there would be at least an accusump plumbed into the system. Probably check 2/6 rod bearings at the end of the season too. Cheaper than a rebuild.
Jim
04-05-2009, 07:16 PM
#4
Nordschleife Master
I have to concure with moving the oil cooler out of the rad, get a large one and it can be tagged into the factory cooler hoses.
I would also add a accusump at the minimum, or preferably a drysump before going back out. Otherwise you are asking for failure!
I would also add a accusump at the minimum, or preferably a drysump before going back out. Otherwise you are asking for failure!
04-05-2009, 07:45 PM
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Coming from somebody that's spun more than one rod bearing in a GT-R RB26 (not to mention a bent crankshaft) - an accusump is a must for a tracked car........
04-05-2009, 07:55 PM
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+1 what H-P wrote. Have been at the track when a 928 shat a rod.
What's wrong with a big-a$$ed accusump and the 3.7-4.0 BAR switch? (Seriously. I'm asking. Will a 1/2/3 QT accusump empty itself in less than 5 seconds if it kicks in at 3.x BAR?)
What's wrong with a big-a$$ed accusump and the 3.7-4.0 BAR switch? (Seriously. I'm asking. Will a 1/2/3 QT accusump empty itself in less than 5 seconds if it kicks in at 3.x BAR?)
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04-05-2009, 08:16 PM
#8
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Guys
Great ideas
I'm thinking get the 55-60 EPC & wire an "off" switch to the dash....something easy to reach that lights up so I will see it.....so when the car is hot and on the cool down lap, turn it "off" which I understand will still allow the accusump to fill if needed, but won't dump oil at the lower idle oil pressures? This way I have maximum protection at the highest pressure and don't have to worry about dumping oil at idle
Install another outboard oil cooler in addition to the factory cooler (since the factory cooler helps heat oil up too).....probably in the bumper...either in the open area where the headlights or foglights went....
I'm thinking an oil change & cutting the filter open is a good idea at this point too....
An accusump seems to be cheap insurance against loosing an engine....since I don't think I am as lucky as MK...even thought we drive the same tracks with the same oil.....
Great ideas
I'm thinking get the 55-60 EPC & wire an "off" switch to the dash....something easy to reach that lights up so I will see it.....so when the car is hot and on the cool down lap, turn it "off" which I understand will still allow the accusump to fill if needed, but won't dump oil at the lower idle oil pressures? This way I have maximum protection at the highest pressure and don't have to worry about dumping oil at idle
Install another outboard oil cooler in addition to the factory cooler (since the factory cooler helps heat oil up too).....probably in the bumper...either in the open area where the headlights or foglights went....
I'm thinking an oil change & cutting the filter open is a good idea at this point too....
An accusump seems to be cheap insurance against loosing an engine....since I don't think I am as lucky as MK...even thought we drive the same tracks with the same oil.....
04-05-2009, 08:22 PM
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04-05-2009, 08:46 PM
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Just remember that the accusump is only protecting you from uncovering the oil pickup during hard cornering/sustained high rpms.
Hot oil is a completely different issue........
Hot oil is a completely different issue........
04-05-2009, 08:56 PM
#11
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Have you tried Mobil 1? 
Will cooling the oil help with oil pickup and possible oil frothing from the crankshaft issues.
Will a straight weight racing oil work better on track?
Will cooling the oil help with oil pickup and possible oil frothing from the crankshaft issues.
Will a straight weight racing oil work better on track?
04-05-2009, 09:09 PM
#12
I'm thinking get the 55-60 EPC & wire an "off" switch to the dash....something easy to reach that lights up so I will see it.....so when the car is hot and on the cool down lap, turn it "off" which I understand will still allow the accusump to fill if needed, but won't dump oil at the lower idle oil pressures?
http://store.summitracing.com/egnsea...115+4294849264
Last edited by soupcan; 04-05-2009 at 09:10 PM. Reason: Added link.
04-05-2009, 09:12 PM
#13
Three Wheelin'
Brian,
Had I seen the pressure drop with hot oil that you saw, that would have been the last lap of the day until it got fixed. That is exactly where I saw my oil pressure dip in my GT and I quit. A few track days later on different tracks, the rod bearing gave up. I did not have an Accusump at the time. I was using Redline 20W 50. I don't think I'd use 15W anything on the track without a huge oil cooler.
Steps.
1) Take off your oil filter and cut it open. Check for any trace of metal.
2) Order an Accusump and related necessary parts. http://www.accusump.com/
3) You can connect your Accusump either to the top line for the oil cooler at the block (fab a T fitting), or to a sandwich connector at the oil filter. If using a sandwich connector, you have to be careful to get one that will fit. The threads are 20mm x 1.5mm, but the room is really tight for the connector to the Accusump line to fit. Some sandwich units have to be drilled through so the oil from the Accusump will get to the engine. That's because you can't use the connector you should use and have to use the other one. Not enough room again.
4) Get as big of an oil cooler as you can fit where air will flow through it. Use ducting so air doesn't just flow around it.
Mocal http://www.batinc.net/coolers.htm makes good ones as does
Fluidyne http://www.fluidyne.com/pl_theoc.html others too. Be sure your oil cooler has large inlet/outlet connectors. AN-12 minumum.
I would suggest taking your oil cooler out of the radiator completely. If you saw 195 coolant temp and it isn't even summer yet what's it going to be in July? Plus you need additional oil cooling and trying to have cooler lines go to the radiator and an additional cooler only complicates things. Run lines from the engine block cooler fittings to an extra cooler and T into the top cooler line for your Accusump. The top cooler fitting goes straight to the filter and on to the engine.
https://rennlist.com/forums/attachme...1&d=1238976687
Had I seen the pressure drop with hot oil that you saw, that would have been the last lap of the day until it got fixed. That is exactly where I saw my oil pressure dip in my GT and I quit. A few track days later on different tracks, the rod bearing gave up. I did not have an Accusump at the time. I was using Redline 20W 50. I don't think I'd use 15W anything on the track without a huge oil cooler.
Steps.
1) Take off your oil filter and cut it open. Check for any trace of metal.
2) Order an Accusump and related necessary parts. http://www.accusump.com/
3) You can connect your Accusump either to the top line for the oil cooler at the block (fab a T fitting), or to a sandwich connector at the oil filter. If using a sandwich connector, you have to be careful to get one that will fit. The threads are 20mm x 1.5mm, but the room is really tight for the connector to the Accusump line to fit. Some sandwich units have to be drilled through so the oil from the Accusump will get to the engine. That's because you can't use the connector you should use and have to use the other one. Not enough room again.
4) Get as big of an oil cooler as you can fit where air will flow through it. Use ducting so air doesn't just flow around it.
Mocal http://www.batinc.net/coolers.htm makes good ones as does
Fluidyne http://www.fluidyne.com/pl_theoc.html others too. Be sure your oil cooler has large inlet/outlet connectors. AN-12 minumum.
I would suggest taking your oil cooler out of the radiator completely. If you saw 195 coolant temp and it isn't even summer yet what's it going to be in July? Plus you need additional oil cooling and trying to have cooler lines go to the radiator and an additional cooler only complicates things. Run lines from the engine block cooler fittings to an extra cooler and T into the top cooler line for your Accusump. The top cooler fitting goes straight to the filter and on to the engine.
https://rennlist.com/forums/attachme...1&d=1238976687
Last edited by Louie928; 06-13-2013 at 05:13 PM.
04-05-2009, 09:14 PM
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Long ago when I went to trade school, early eighties, the rule of thumb was 7 psi per thousand RPM, so that would mean, 2 bar @4000rpm is perfectly acceptable.
Cheers Roy
Cheers Roy
04-05-2009, 10:48 PM
#15
Race Director
Thread Starter
Brian,
Had I seen the pressure drop with hot oil that you saw, that would have been the last lap of the day until it got fixed. That is exactly where I saw my oil pressure dip in my GT and I quit. A few track days later on different tracks, the rod bearing gave up. I did not have an Accusump at the time. I was using Redline 20W 50. I don't think I'd use 15W anything on the track without a huge oil cooler.
Steps.
1) Take off your oil filter and cut it open. Check for any trace of metal.
2) Order an Accusump and related necessary parts. http://www.accusump.com/
3) You can connect your Accusump either to the top line for the oil cooler at the block (fab a T fitting), or to a sandwich connector at the oil filter. If using a sandwich connector, you have to be careful to get one that will fit. The threads are 20mm x 1.5mm, but the room is really tight for the connector to the Accusump line to fit. Some sandwich units have to be drilled through so the oil from the Accusump will get to the engine. That's because you can't use the connector you should use and have to use the other one. Not enough room again.
4) Get as big of an oil cooler as you can fit where air will flow through it. Use ducting so air doesn't just flow around it.
Mocal http://www.batinc.net/coolers.htm makes good ones as does
Fluidyne http://www.fluidyne.com/pl_theoc.html others too. Be sure your oil cooler has large inlet/outlet connectors. AN-12 minumum.
I would suggest taking your oil cooler out of the radiator completely. If you saw 195 coolant temp and it isn't even summer yet what's it going to be in July? Plus you need additional oil cooling and trying to have cooler lines go to the radiator and an additional cooler only complicates things. Run lines from the engine block cooler fittings to an extra cooler and T into the top cooler line for your Accusump. The top cooler fitting goes straight to the filter and on to the engine.
https://rennlist.com/forums/attachme...1&d=1238976687
Had I seen the pressure drop with hot oil that you saw, that would have been the last lap of the day until it got fixed. That is exactly where I saw my oil pressure dip in my GT and I quit. A few track days later on different tracks, the rod bearing gave up. I did not have an Accusump at the time. I was using Redline 20W 50. I don't think I'd use 15W anything on the track without a huge oil cooler.
Steps.
1) Take off your oil filter and cut it open. Check for any trace of metal.
2) Order an Accusump and related necessary parts. http://www.accusump.com/
3) You can connect your Accusump either to the top line for the oil cooler at the block (fab a T fitting), or to a sandwich connector at the oil filter. If using a sandwich connector, you have to be careful to get one that will fit. The threads are 20mm x 1.5mm, but the room is really tight for the connector to the Accusump line to fit. Some sandwich units have to be drilled through so the oil from the Accusump will get to the engine. That's because you can't use the connector you should use and have to use the other one. Not enough room again.
4) Get as big of an oil cooler as you can fit where air will flow through it. Use ducting so air doesn't just flow around it.
Mocal http://www.batinc.net/coolers.htm makes good ones as does
Fluidyne http://www.fluidyne.com/pl_theoc.html others too. Be sure your oil cooler has large inlet/outlet connectors. AN-12 minumum.
I would suggest taking your oil cooler out of the radiator completely. If you saw 195 coolant temp and it isn't even summer yet what's it going to be in July? Plus you need additional oil cooling and trying to have cooler lines go to the radiator and an additional cooler only complicates things. Run lines from the engine block cooler fittings to an extra cooler and T into the top cooler line for your Accusump. The top cooler fitting goes straight to the filter and on to the engine.
https://rennlist.com/forums/attachme...1&d=1238976687
Great info from someone who was BTDT.....I hope my motor is okay??? I did see the lowest pressures on the last run of the day....which is good I hope?
so I have quite a list of "to do's" before I hit the track again...time for a cooler and accusump!!! Good thing its 3 weeks away!
Having to replace the engine does not sound like much fun......