Does anything actually solve the oil pressure drop in corners?
09-20-2020, 05:33 PM
#76
Rennlist Member
Was there one for the 996? While lots of parts are the same, the cylinder halfs and heads are not the same part number(what I can see). There could be a simple restriction(smaller passages for example) somewhere in there giving the Boxster higher oil pressure. Since this is for the 986, I believe the manual is still ok in this instance. If some one can find a TSB pointing the other way, do post.
The M1 0w40 is a thin 40wt oil, it's 12.9cst when new. 12.5 to 16.3 cst is 40wt and 12.5 - 9.3 cst is 30wt. Reading UOAs the M1 0w40 in 996s, it is at 11.5-12 already around 3-4000mils, thus sheared to 30wt. If you follow the 15,000mil service, the actual oil weight in the engine would be mid to low 30wt at that time. When you change oil, there is some left in the engine. When doing a new fill of 0w40 after 15,000 mil you dilute your new oil with some old. Basically if following Porsche's oil and change interval recommendation, you run 30wt in you car.
To all contributors to this thread, I'm trying to find the solution to this. Some times I will push you a little to get more/correct information. Sorry Porschetech3(and others) if you find it offensive, I'm not here to put anyone in a corner.
The M1 0w40 is a thin 40wt oil, it's 12.9cst when new. 12.5 to 16.3 cst is 40wt and 12.5 - 9.3 cst is 30wt. Reading UOAs the M1 0w40 in 996s, it is at 11.5-12 already around 3-4000mils, thus sheared to 30wt. If you follow the 15,000mil service, the actual oil weight in the engine would be mid to low 30wt at that time. When you change oil, there is some left in the engine. When doing a new fill of 0w40 after 15,000 mil you dilute your new oil with some old. Basically if following Porsche's oil and change interval recommendation, you run 30wt in you car.
To all contributors to this thread, I'm trying to find the solution to this. Some times I will push you a little to get more/correct information. Sorry Porschetech3(and others) if you find it offensive, I'm not here to put anyone in a corner.
Lets see if you can answer that simple question and make any since of it..
09-20-2020, 05:53 PM
#77
Rennlist Member
Nick, lets cut straight to the chase. YOU say you and Porsche wants 3.5 bar oil pressure max? IF so, why did Porsche even put the 5 bar pressure relief valve in the m96 engine? Why didn't they put a 3.5 bar pressure relief valve in instead like you want?
Lets see if you can answer that simple question and make any since of it..
Lets see if you can answer that simple question and make any since of it..
09-20-2020, 06:03 PM
#78
Racer
I have never said that I want 3.5bar max. 3.5bar at 5k does not mean it's max pressure, you can increase pressure by revving higher if you want. The 3.5bar at 5k is a measure and gauge point, like the 986 TSB. Let me explain. (on a side note, 3.5 bar at 5k follows the engine builders rule of thumb of 10psi per 1k rpm)
When the pressure relief valve is open, you are wasting power. For highest efficiency you want a pump which delivers correct pressure all the time without wasting anything. Wasted power in this case turns up as heat and heats the oil, unnecessary.
By setting the pressure at 3.5bar at 5k rpm you assure that the pressure relief valve is not in continues use while driving hard. The 911 is NA sports car, it's designed to run at high RPM for a long time. This is different from other cars you see which briefly accelerate and then keeps a steady economical RPM. Like the Ford in the MIT paper. That engine spends majority of it's life below 3k rpm and that shows in the oil pump.
Not only does bypassing create heat, it also contributes to aeration. It's important, in a high revving sports car engine, to not run in to bypassing.
The pressure drops I experience are at moderat g forces. My calculations show that it's highly unlikely that my pick-up sucks air, much much more likely that the oil is aerated. The X51 pan is not helping in this regard as the inlet ports sits higher and suck oil from higher up in the oil level.
When the pressure relief valve is open, you are wasting power. For highest efficiency you want a pump which delivers correct pressure all the time without wasting anything. Wasted power in this case turns up as heat and heats the oil, unnecessary.
By setting the pressure at 3.5bar at 5k rpm you assure that the pressure relief valve is not in continues use while driving hard. The 911 is NA sports car, it's designed to run at high RPM for a long time. This is different from other cars you see which briefly accelerate and then keeps a steady economical RPM. Like the Ford in the MIT paper. That engine spends majority of it's life below 3k rpm and that shows in the oil pump.
Not only does bypassing create heat, it also contributes to aeration. It's important, in a high revving sports car engine, to not run in to bypassing.
The pressure drops I experience are at moderat g forces. My calculations show that it's highly unlikely that my pick-up sucks air, much much more likely that the oil is aerated. The X51 pan is not helping in this regard as the inlet ports sits higher and suck oil from higher up in the oil level.
09-20-2020, 06:31 PM
#79
Rennlist Member
I have never said that I want 3.5bar max. 3.5bar at 5k does not mean it's max pressure, you can increase pressure by revving higher if you want. The 3.5bar at 5k is a measure and gauge point, like the 986 TSB. Let me explain. (on a side note, 3.5 bar at 5k follows the engine builders rule of thumb of 10psi per 1k rpm)
When the pressure relief valve is open, you are wasting power. For highest efficiency you want a pump which delivers correct pressure all the time without wasting anything. Wasted power in this case turns up as heat and heats the oil, unnecessary.
By setting the pressure at 3.5bar at 5k rpm you assure that the pressure relief valve is not in continues use while driving hard. The 911 is NA sports car, it's designed to run at high RPM for a long time. This is different from other cars you see which briefly accelerate and then keeps a steady economical RPM. Like the Ford in the MIT paper. That engine spends majority of it's life below 3k rpm and that shows in the oil pump.
Not only does bypassing create heat, it also contributes to aeration. It's important, in a high revving sports car engine, to not run in to bypassing.
The pressure drops I experience are at moderat g forces. My calculations show that it's highly unlikely that my pick-up sucks air, much much more likely that the oil is aerated. The X51 pan is not helping in this regard as the inlet ports sits higher and suck oil from higher up in the oil level.
When the pressure relief valve is open, you are wasting power. For highest efficiency you want a pump which delivers correct pressure all the time without wasting anything. Wasted power in this case turns up as heat and heats the oil, unnecessary.
By setting the pressure at 3.5bar at 5k rpm you assure that the pressure relief valve is not in continues use while driving hard. The 911 is NA sports car, it's designed to run at high RPM for a long time. This is different from other cars you see which briefly accelerate and then keeps a steady economical RPM. Like the Ford in the MIT paper. That engine spends majority of it's life below 3k rpm and that shows in the oil pump.
Not only does bypassing create heat, it also contributes to aeration. It's important, in a high revving sports car engine, to not run in to bypassing.
The pressure drops I experience are at moderat g forces. My calculations show that it's highly unlikely that my pick-up sucks air, much much more likely that the oil is aerated. The X51 pan is not helping in this regard as the inlet ports sits higher and suck oil from higher up in the oil level.
If you want to tune your oil pressure to 3.5 bar at 5k operating temp, be my guest. You can use thinner oil, rebuild your engine with looser tolerance , or weaken the pressure relief/by-pass spring.( to 3.5 bar).
If you just want to eliminate the drop on turns, I think Silks concept is the ticket.. In fact, a Partner (Rennlister) and I are considering designing a dual pick-up hardware/device using a similar concept but using g-force actuated simple mechanical valves instead of baffles, even though I don't have this issue on my 996 and have tracked it hard with oil temp up 250F..
Last edited by Porschetech3; 09-20-2020 at 06:54 PM.
09-20-2020, 06:54 PM
#80
Racer
No, you can not weaken the pressure relief spring. Then you will run in to bypassing much earlier(wasting more power) and not achieve the required 5bar at redline. Rebuilding with looser tolerances is just non-sense. You have yourself written that this car can run, in stock form, on track without pressure drops.
You tune this by oil viscosity. Use 0w40 for 15,000 mil changes.... .or choose a 30wt oil and change more frequently.
That's what I'm about to try out, it makes sense both logically and theoretically.
You tune this by oil viscosity. Use 0w40 for 15,000 mil changes.... .or choose a 30wt oil and change more frequently.
That's what I'm about to try out, it makes sense both logically and theoretically.
09-20-2020, 07:02 PM
#81
Rennlist Member
No, you can not weaken the pressure relief spring. Then you will run in to bypassing much earlier(wasting more power) and not achieve the required 5bar at redline. Rebuilding with looser tolerances is just non-sense. You have yourself written that this car can run, in stock form, on track without pressure drops.
You tune this by oil viscosity. Use 0w40 for 15,000 mil changes.... .or choose a 30wt oil and change more frequently.
That's what I'm about to try out, it makes sense both logically and theoretically.
You tune this by oil viscosity. Use 0w40 for 15,000 mil changes.... .or choose a 30wt oil and change more frequently.
That's what I'm about to try out, it makes sense both logically and theoretically.
I use 5w-50 in my 180k mile 996 and love my pressure, and don't have any issue with drops in corners with stock oil capacity.
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paddlefoot64 (09-21-2020)
09-21-2020, 12:29 AM
#82
Burning Brakes
Thread Starter
The very first M9X engine failure I experienced with my program was due to the factory oil pump hex drive shear
At the end of the day, you are reinventing the wheel for no real reason. 95% of the people on this forum can't create a scenario where the stock oil system is put over the edge, as long as oil temperatures are kept in check. Keep the oil cool, and that's all you need to do. I have several hundred examples that prove this, some in service since 2008, like the engine that @ltusler has had in his 996 since late 2008, which has only seen the track.
Just keep the oil cool, then the rest works. You are much more likely to become a zero, by trying to be the hero who solves the problems with this oil system, that you'll likely never experience if you just keep the oil cool. The enemy of excess oil temperatures lies in the factory engine oil/ coolant "heat exchanger"... You notice that I didn't refer to it as an "oil cooler".
09-21-2020, 02:36 AM
#83
Drifting
No, you can not weaken the pressure relief spring. Then you will run in to bypassing much earlier(wasting more power) and not achieve the required 5bar at redline. Rebuilding with looser tolerances is just non-sense. You have yourself written that this car can run, in stock form, on track without pressure drops.
You tune this by oil viscosity. Use 0w40 for 15,000 mil changes.... .or choose a 30wt oil and change more frequently.
That's what I'm about to try out, it makes sense both logically and theoretically.
You tune this by oil viscosity. Use 0w40 for 15,000 mil changes.... .or choose a 30wt oil and change more frequently.
That's what I'm about to try out, it makes sense both logically and theoretically.
My personal solution to this problem was running older, and therefore a bit slippery, Sumitomo HTRZ III tires. Less lateral Gs...
09-21-2020, 04:12 AM
#84
Rennlist Member
I would not try this idea if I were you...even if it gives you your desired oil pressure (whatever that is), it will cause other problems.
My personal solution to this problem was running older, and therefore a bit slippery, Sumitomo HTRZ III tires. Less lateral Gs...
My personal solution to this problem was running older, and therefore a bit slippery, Sumitomo HTRZ III tires. Less lateral Gs...
When he says things like "the oil pump drive is designed to break" and "the sump baffles are not to keep more oil around the pick-up tube".and so much more, I'd have to type for hours just try and correct it all.
09-21-2020, 04:37 AM
#85
Racer
I would not try this idea if I were you...even if it gives you your desired oil pressure (whatever that is), it will cause other problems.
My personal solution to this problem was running older, and therefore a bit slippery, Sumitomo HTRZ III tires. Less lateral Gs...
My personal solution to this problem was running older, and therefore a bit slippery, Sumitomo HTRZ III tires. Less lateral Gs...
The condition of your car, they way you drive and the climate/terrain where you drive all makes a difference. Running thicker oil will work for some because of these different factors. By changing oil more frequently you are effectively running thicker oil also.
What I'm going to try is within the boundaries of the manual, it just happens to disagree with the common belief here on Rennlist. I do think it's ok to follow the manual. Some information in the manual have been superseded by TSB information, but it's still in large part accurate.
09-21-2020, 04:46 AM
#86
Racer
Look at the drive of the head scavenge pumps, same designed break point there. Isn't that a coincidence.....
09-21-2020, 07:49 AM
#87
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Hey Nick...just do it. Quit yacking. Do your study and in five (5) years get back to us. Be sure to include a full tear down of your engine and UOA. "hands over ears" la la la la laaaa laaaa laa la la la lala la la la.......
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Porschetech3 (09-22-2020)
09-21-2020, 09:03 AM
#88
Rennlist Member
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09-21-2020, 11:35 AM
#89
Rennlist Member
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Porschetech3 (09-22-2020)
09-21-2020, 01:23 PM
#90
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Well, that is one solution. Can you elaborate what problems I might run in to? Maybe I have overlooked something.
The condition of your car, they way you drive and the climate/terrain where you drive all makes a difference. Running thicker oil will work for some because of these different factors. By changing oil more frequently you are effectively running thicker oil also.
What I'm going to try is within the boundaries of the manual, it just happens to disagree with the common belief here on Rennlist. I do think it's ok to follow the manual. Some information in the manual have been superseded by TSB information, but it's still in large part accurate.
The condition of your car, they way you drive and the climate/terrain where you drive all makes a difference. Running thicker oil will work for some because of these different factors. By changing oil more frequently you are effectively running thicker oil also.
What I'm going to try is within the boundaries of the manual, it just happens to disagree with the common belief here on Rennlist. I do think it's ok to follow the manual. Some information in the manual have been superseded by TSB information, but it's still in large part accurate.
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Porschetech3 (09-22-2020)