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Your accusump thoughts are in line with what others have said but frankly, not sure what options exist and maintaining this status quo is likely not a good idea for long, or short term reliability. If you have personal experience with the accusump I would love to hear, most people say not worth it but have not run themselves.
No discrete oil temp gauge, this last event though ambient was 43F so not likely to see a better scenario for non thinned oil then than that without changing parts and adding additional oil/coolant cooling capacity.
thats the same thing i have. doesn't do much it seems.
I have not personally run the accusump, so theres that, but a lot of SPB racers tried it and eventually went away from it because of the complexity, steps to ensure it was going to work, additional plumbing, etc. Its not too expensive to try but eh.
A gentleman in the 996 forum had some sort of dual pickup made, but when I contacted his shop, I got no response.
I rebuilt an m97 with my friend for his spec cayman, and we were very diligent about bearing clearance and even deleted the piston squirters to try to keep pressure up. He still has regular pressure drops, as low as 15 psi in some turns (which is consistent with my car). I think the mid engine cars may be worse, but event still.
You could try to rig up a dry sump, but thats an expensive process.
At this point, I think your best bet is to keep the oil cool and run a good oil and accept the fact that the motor might lunch itself at pretty much any point.
From what I have read and when I was dreaming of a dry sump To resolve a host of M96 issues I read a bunch of stuff from CTS, CTS seems to be the only one to have figured out legit solutions and backed with data.
If you want to help out a lowly 996 track car, hit me up and thanks for poking in here.
Is the above graph with accusump or one of your dry sump systems ?
No discrete oil temp gauge, this last event though ambient was 43F so not likely to see a better scenario for non thinned oil then than that without changing parts and adding additional oil/coolant cooling capacity.
I think the lack of an oil temp gauge is the most absurd decision about the entire car. I would add one as soon as possible.
Ashai wrote up a post on how to tap the existing oil temp sensor and add a dash gauge.
I did something similar for my Turbo; the Turbo's oil temp sensor is not at all the same as the NA car so I mostly used the concept. That little readout below the clock shows oil temp. If you want a hand doing something similar let me know.
I think the lack of an oil temp gauge is the most absurd decision about the entire car. I would add one as soon as possible.
Ashai wrote up a post on how to tap the existing oil temp sensor and add a dash gauge.
I did something similar for my Turbo; the Turbo's oil temp sensor is not at all the same as the NA car so I mostly used the concept. That little readout below the clock shows oil temp. If you want a hand doing something similar let me know.
Thanks Aaron. I know nothing about electrical... I like that solution. It is likely that I will be adding a dash display over the winter so I can view, monitor and alarm some of the critical paremeters.
If it wasn't for the video, I never would have known about the pressure dip - it happened so quickly and at a point of the track 100% or my focus was on hitting the spot - I was very surprised to see it when I focussed on it rewatching.
Looking at the data log, looks like a low oil pressure of 2.3 at 3K RPM and little over 1G but at 4K RPM roughly same G loading its at 3.4 I wonder what the oil temp was.
From my video, stock gauge reading slightly above 2 bar at 4K RPM at around .8-1G on the GoPro...
Looks like that motor had at least 1 BAR better pressure under similar circumstance, but - that is the only spot on THAT track where that set of circumstances led to a pressure drop on that day for me - I really wish I had better data.
[QUOTE=zbomb;17048507]Looking at the data log, looks like a low oil pressure of 2.3 at 3K RPM and little over 1G but at 4K RPM roughly same G loading its at 3.4 I wonder what the oil temp was.
From my video, stock gauge reading slightly above 2 bar at 4K RPM at around .8-1G on the GoPro...
Looks like that motor had at least 1 BAR better pressure under similar circumstance, but - that is the only spot on THAT track where that set of circumstances led to a pressure drop on that day for me - I really wish I had better data.
[QUOTE=zbomb;17048507]
You'll notice that OP follows RPM exactly. The spikes you see in the OP trace are the result of the RPM going up and down quickly due to downshifting blips.
The pressure difference you note is not real. The data engine has the oil pressure sensor in the oil cooler (very close to the main bearings) and your engine is reading from the valve cover, which will read quite a bit less due to the pressure drop thru the various passages. Your pressure gauge reacts very slowly so you are seeing roughly a 1 second average. A 25 hz datalog like you see here would show spikes down to 1 bar, which is the pressure generated by the pump when it is pumping only air.
Oil temp is about 213. There is a temp trace on there.
Once you get up near 1G each additional increment of G does not affect the sloshing much. You can do the math on this.
Average RPM is a very big factor in all this. This is why the 2.5 Boxster engines last the longest. Redline is 6700 and the gears are widely spaced. Average RPM over the lap is at least 500 rpm lower than a 996.
You'll notice that OP follows RPM exactly. The spikes you see in the OP trace are the result of the RPM going up and down quickly due to downshifting blips.
The pressure difference you note is not real. The data engine has the oil pressure sensor in the oil cooler (very close to the main bearings) and your engine is reading from the valve cover, which will read quite a bit less due to the pressure drop thru the various passages. Your pressure gauge reacts very slowly so you are seeing roughly a 1 second average. A 25 hz datalog like you see here would show spikes down to 1 bar, which is the pressure generated by the pump when it is pumping only air.
Oil temp is about 213. There is a temp trace on there.
Once you get up near 1G each additional increment of G does not affect the sloshing much. You can do the math on this.
Average RPM is a very big factor in all this. This is why the 2.5 Boxster engines last the longest. Redline is 6700 and the gears are widely spaced. Average RPM over the lap is at least 500 rpm lower than a 996.
Chris
I see the oil temp, thanks - the rock steady line fooled me.
Thanks for the info - would be interesting to see a log of a stock or deep sump equipped motor for comparison.
This kind of data and your experience is interesting and very rare to see, thank you for taking the time to post it.
In order to decrease the total oil flow and pressure to the cylinder heads, and to increase the total oil flow and pressure to the main bearings, a total of 6 oil restrictors are installed in each cylinder head. The details are described below. The design target was to reduce the cylinder head oil pressure to 60% of that of the main bearings. The restrictors greatly reduce the volume of oil captured in the heads. Under race conditions, the oil tank level is approximately 2 quarts higher than without the restrictors.
Based off this statement, the extra capacity from my deep sump is just sitting in the heads. That would lead me to believe that under the right conditions the reduced oil in the sump coupled with the right combination of forces have moved a sufficient amount of oil away from the pickup to allow it to pick up air momentarily.
And this is not helping with oil sump volume, and would make some sense in my case seeing the pressure drop after a sweeper then hard on the brakes:
Originally Posted by CTS
The second scavenge circuit attempts to pull oil out of the high volume Z-shaped area formed by the intermediate shaft area and the two cam chain housings. Under acceleration, oil runs backwards to the intermediate shaft chain area where it is collected by the scavenge system. This area collects several liters of oil otherwise. In order to prevent the intermediate shaft chain from running without lubrication, the scavenge point is higher than the lowest area that the chain occupies. From there the oil travels through a hose to the dry sump pump assembly.
That being the case, short of having a bottomless sump, or restricting the flow of oil to the head where it overwhelms the return, keeping enough oil in the sump to assure an uninterrupted supply to the pickup is a tough row to hoe.
I have started to get a pretty good stash of parts set aside and since the snow is now falling here in MA, I thought updating the thread with some parts I have, some parts I need would be a good distraction.
Pictured below
Front Adjustable Tie Rods
Rear Adjustable Toe Links
Read Adjustable Drop Links
Mono ball wishbones
Elephant adjustable front camber plates
Motec ADL2 with harness
Not pictured
Cup Rear Sway
GT3 Master Cylinder
Steel Brake lines
Schroth Hans Harness
I still need to figure out what I'm going to do for LCA's and if I'm going to do caster arms... The Motec came out of the cup car I'm parting out and I need to piece together the parts I still need to get it in the car and collecting the data I want. As Can from the stock ECU is not going to give me very much data, it's not as simple as plug and go. The harness is currently configured for GPS, G force, brake pressure, steering angle, and shift light - so I still have a fair amount of work to do to get it usable in the car, currently seeking experienced help on that front. If it ends up being uneconomical, I will sell it and put an Aim in the car.
11-24-2020, 11:38 AM
