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wow! thanks for the links. Reading Chris's thread about his dry sump is pretty amazing. This is the graph we want! Oil pressure mimics RPM. It's perfect.
His comments about the inevitability of the engines demise is disheartening. And unfortunately with my quick learning, I agree with him. Not to be defeated, yet, but not having the resources or expertise to reinvent a dry sump, the next discussion would be about why the deep sumps fail or all the baffling has failed. The issue turns into a time issue. The oil returning to the sump needs to be in a position to be pushed(!) into the pickup well before it's needed. So the design needs to be for collectors to direct the oil to a cylindrical baffle around the pickup. If this could be kept full at the rate conjectured above, the issue should go away. The idea is to decrease the time it takes to get the oil returning to the sump to the pickup and not let it lolligag it's way to happen across the pickup. I like the idea of being able to see into the sump as its running. Some thick polycarbonate (maybe not high enough temp) would allow some observation for how the oil is returning. Maybe its already obvious and I'm just a noob, only having seen the LN deep sump kit online. It's a time and flow control problem
wow! thanks for the links. Reading Chris's thread about his dry sump is pretty amazing. This is the graph we want! Oil pressure mimics RPM. It's perfect.
His comments about the inevitability of the engines demise is disheartening. And unfortunately with my quick learning, I agree with him. Not to be defeated, yet, but not having the resources or expertise to reinvent a dry sump, the next discussion would be about why the deep sumps fail or all the baffling has failed. The issue turns into a time issue. The oil returning to the sump needs to be in a position to be pushed(!) into the pickup well before it's needed. So the design needs to be for collectors to direct the oil to a cylindrical baffle around the pickup. If this could be kept full at the rate conjectured above, the issue should go away. The idea is to decrease the time it takes to get the oil returning to the sump to the pickup and not let it lolligag it's way to happen across the pickup. I like the idea of being able to see into the sump as its running. Some thick polycarbonate (maybe not high enough temp) would allow some observation for how the oil is returning. Maybe its already obvious and I'm just a noob, only having seen the LN deep sump kit online. It's a time and flow control problem
well, id like to say that would solve the problem, but this is why a lot of the deep sump kits swap the 996 style swirl pot return tubes to the straight shot 997 returns. The issue is aeration. The swirl pots delay oil return but supposedly reduce aeration. The 997 returns are quicker, but don't de-aerate the oil. They return the oil outside of the stock baffle to supposedly give the oil time to dissipate the bubbles.
there is a guy on youtube who makes clear covers for combustion chambers and such, so I'm sure he could do this, but would need a test car and a track.
This was from CTS, boxster with a deep sump... looks familiar.
Again to highlight - if you are driving an M96 on track - is this happening to you ? It’s now got me curious to see what guys who only use their cars on the street should expect...
Im going to log a spirited run on the road and see...
Anyway... another data point as said above... boxster with unnamed deep sump.
The deep sump pans, by themselves, don’t always fix the issue because:
1.) Aeration is still present, no matter how much oil you have. Actually, more oil can lead to more aeration. Counter-intuitive, but it’s the windage effect.
2.) The baffles don’t help that much. Like Accu-sump, you could be robbing Peter to pay Paul. Having a baffle sounds good, until you realize that the compartment to hold that oil is much smaller than the overall amount, so it can be depleted faster.
3.) A pickup tube that can rotate the way some aircraft engines have rotating pickups are absolutely required to prevent starvation, or else a deep dry sump external tank that is so tall as to never lose oil around the pickup is required. Sorry, aerated oil that’s seeing a 0.9+g force is going to be held up on it’s side. Unless the pickup is at the centrifugal center of where the mass is, it will likely suck air.
All of the above also requires something in place to de-aerate the oil in the first place.
By the way, we don’t need high temp to have aerated oil. To test, just put a cup of oil in a blender and watch it turn white after 10 seconds.
The deep sump pans, by themselves, don’t always fix the issue because:
1.) Aeration is still present, no matter how much oil you have. Actually, more oil can lead to more aeration. Counter-intuitive, but it’s the windage effect.
2.) The baffles don’t help that much. Like Accu-sump, you could be robbing Peter to pay Paul. Having a baffle sounds good, until you realize that the compartment to hold that oil is much smaller than the overall amount, so it can be depleted faster.
3.) A pickup tube that can rotate the way some aircraft engines have rotating pickups are absolutely required to prevent starvation, or else a deep dry sump external tank that is so tall as to never lose oil around the pickup is required. Sorry, aerated oil that’s seeing a 0.9+g force is going to be held up on it’s side. Unless the pickup is at the centrifugal center of where the mass is, it will likely suck air.
All of the above also requires something in place to de-aerate the oil in the first place.
By the way, we don’t need high temp to have aerated oil. To test, just put a cup of oil in a blender and watch it turn white after 10 seconds.
1. Windage is a real thing, but with how the M96 is designed, I'm not seeing this to be an issue while the engine is running. Given how much oil is retained in the heads and how high the crank is vs. the oil pickup, I can't imagine that the crank is whipping the oil.
2. While it is depleted faster, when there are any G forces, oil should essentially always be flowing through the trap doors. Especially when you prevent oil from climbing the walls of the sump with a horizontal baffle.
3. It would certainly help, but i don't think this is a perfect solution. I would think if it was this easy, people would have built this. Engines like an S54 just use a 2 pickup solution with a fairly isolated deep well sump and don't appear to suffer from starvation.
I wish someone could make a clear acrylic sump plate and get a video camera focused on that for a couple laps to see whats happening.
Back in the day I was involved with a project on medium speed marine diesel engines to figure out where the oil was going. A "medium speed" marine diesel typically has a redline of about 600 RPM. The particular engine I was working on was a Pielstick 18V, 18 cylinder V type rated 9,000 HP @ 530 RPM. As you might think rebuilds are not cheap... we instrumented the crankcase with ultrasonic distance sensors made by Polaroid to measure the air gap above the oil level. This worked OK but not great as any oil mist in the crankcase would fool the sensors.
I don't think this would work well in a high-speed application like a car engine as the crankcase is much smaller and I suspect the oil mist factor is much greater. Besides Polaroid doesn't make the sensors anymore as far as I know. The factory electronic oil level gauge uses resistors and temperature changes to measure the oil level, it's not particularly accurate and very slow responding. A TV camera would get covered in oil almost immediately. Perhaps an array of float switches would work.
1Engines like an S54 just use a 2 pickup solution with a fairly isolated deep well sump and don't appear to suffer from starvation.
I wonder how they organize a dual pickup to prevent one pickup from sucking air. Perhaps grafting an S54 oil pickup onto the M96 would solve some of the problems.
1. This is one you can throw parts at and work your way up in cost and how invasive or complexity adding the changes are.... start with stock turbo rads, then center rad, then maybe CSF turbo side rads, then there is the oil cooler which as you said, seems very likely to be a big pain in the ***.
2. By incrementally adding cooling capacity, if you can get to an acceptable point - you can reallocate any additional funds ear marked for the next attempts to something else...like tires 👍
3. The consequence for lack of progress is low... get a sump or pump modification right enough... then wrong at the wrong time could put you in a bad place. Put some new rads on hoping to lower oil temps and have it fail to accomplish your goal... you’re out the money and your time.
All this rings true.
The oil to water heat exchanger is going to have a delta-T between the oil and the water. This should be constant unless the heat exchanger is getting overwhelmed. Essentially the oil should be "x" degrees hotter than the water under all conditions. I think the data shows the oil is 30 degrees hotter than the water at it's highest.
Adding cooling capacity will help, if the water temp is high and especially if the water temp changes with ambient air temp. I seem to remember 220F water temperatures; I think those can be lowered with greater cooling capacity.
An aside. For reference while at Lime Rock last week running the Turbo pretty hard (but not as hard as Z runs his car!) I had a highest water temp of 187, ambient air temp was about 75. This is with the oil cooler, automatic transmission, and engine adding heat to the water. The highest oil temp I saw was 227F and it stayed under 220 most of the time. The ATF hung out around 200F. (I have oil temp and ATF temp gauges). I suspect the Turbo engine has a higher capacity water pump. It certainly has a much bigger oil to water heat exchanger. The radiator cores are almost twice as thick. The airflow into the radiators is somewhat better with the larger openings. The exit slots in front of the wheels (which Z has added) probably help too.
So there should be room to lower the water temp on the C2, which should have a knock-on effect on the oil temp - unless the oil to water heat exchanger is getting overwhelmed. Then the Cayman part could be the next step.
87 at Palmer tomorrow... Likely we'll see what the stock cooling capacity for both oil and water really look like, I would say for most of us, I have run in cool to downright cold ambients so far this year with the exception of the last couple sessions when we were at Palmer, even then - it was probably mid to low 70's. Other than that, and for all instances data has been posted, its been around 50 or under.
Same discussion about oil return lines in the sump vs aeration from some years ago. https://rennlist.com/forums/996-foru...wirl-pots.html
-Discussed is why the returns aren't directed at the pickup. Consensus is that more time is needed to get rid of the air and foam. Foam and air will rise to the top as the oil travels across the pan to the pickup. Part of the baffles job is to block the foam from getting to the pickup. This is why the swirl pots in 996 and return tubes in 997 are pointed towards the outside wall of the sump.
-There is one mention that LN deep sump with 997 return lines solved the pressure drops (only data is visual from the gauge) while others say it didn't help. Jake adds a comment that the current tolerances in the engine 'everywhere' is a big factor in how much pressure drop you will get
-The 2 scavenge pumps per head is also discussed. This seems more rare than the CTS dry sump.
Too bad I didn't read all this before all the talking. Sounding like the 3 year broken record... Apologies to those that have been through this before. The data in this discussion is way better.
So, based on the discussions and data here's what I think the best setup is with available parts:
-CSF or bigger radiators
-Center radiator
-Bigger oil heat exchanger
-997 oil returns
-LN deep sump kit
If the pressure drops are still seen, take the engine apart and go find the 'loose' bearings...
Otherwise, resurrect the CTS dry sump or spend some time to develop a clever de-airing system that would reduce the time for clear oil to the pickup. What size screen is needed to filter the air and foam out of the oil? (easy question to ask when you have no idea about the bubble sizes and flow rates and such)
In my opinion, the Go-Fund-Me account should continue for the very reason that we are all looking for oil starvation solutions to prolong engine life in our cars, as it relates to oil pressure drops. What we are looking to do is analyze in sequential form whether specific enhancements actually work.
With that being said, we all know that eventually our engines will need to be rebuilt. It happens to every engine that has ever been built in the history of engines. We know it costs a lot of money to rebuild regardless of who or how you choose to do it. And we know why the engine fails and what causes it. (1) Ims, (2) bore scoring, (3) oil starvation.
The purpose is to find affordable oil starvation solutions in a logical sequence that can be tested to see if they actually work. Remember, this is not an exercise to determine if our 996 engines are a better choice or not to a GT3 engine or a Chevy engine in creating a race car. CTS, and everyone else knows that there is always a better engine design for racing. None of us can argue with that.
Our purpose is to find viable solutions to prolong engine life so we can enjoy our cars on the street and track until we decide it's time to rebuild.
So with all this being said, my suggestion is that we come up with a logical sequence of parts/procedures that should be tested and funded. I suspect if we Frame this mission properly, we can increase the contributions.
I would gladly do it with my car, but I have zero mechanical skills and rely on my shop to do these things and the costs will be astronomical. Jason was kind enough to agree to the pumps since he has the AIM system to analyze and measure whether the part or procedure works, and more importantly the mechanical skills to do it, and the communication skills to detail and share it.
Maybe Jason would be open to doing more than pumps, or even changing the sequence of enhancements given the previous posts suggested in this thread, if it can be funded by Go-Fund-Me contributions. No harm if Jason doesn't want to do it. It's a big ask. Maybe it is someone else. Or maybe we just forget about it and regroup later.
My thoughts and suggestions may be completely off base, but Skip's message created an opportunity to frame out a clear purpose. I am open to however everyone wants to proceed.
Can't contribute as much to this thread technically but I just donated! Love seeing the data shared and the collective brain power try to solve this. Z - I'm looking forward to seeing how this issue presents itself during a spirited back roads rip.
1. Windage is a real thing, but with how the M96 is designed, I'm not seeing this to be an issue while the engine is running. Given how much oil is retained in the heads and how high the crank is vs. the oil pickup, I can't imagine that the crank is whipping the oil.
2. While it is depleted faster, when there are any G forces, oil should essentially always be flowing through the trap doors. Especially when you prevent oil from climbing the walls of the sump with a horizontal baffle.
3. It would certainly help, but i don't think this is a perfect solution. I would think if it was this easy, people would have built this. Engines like an S54 just use a 2 pickup solution with a fairly isolated deep well sump and don't appear to suffer from starvation.
1.) Windage happens in pretty much all engines. It cannot be easily avoided in such a small package. That’s primarily how oil becomes aerated in the first place. As long as the pickup is pulling in oil, aeration is not as much of an issue.
2.) Should, I agree. But…there are countless posts on folks still having oil pressure drops with all these aftermarket pans installed. If it worked so well, bingo, problem solved, let’s move on. Yet the issue continues. Air is getting sucked in regardless.
3.) It’s not easy, and it’s not cheap. Thus, the reason Porsche decided to go away from dry sump to hybrid sump.
Last edited by Mike Murphy; 05-22-2021 at 12:51 PM.
05-21-2021 | 03:05 PM
