Thoughts on Drop In Oil Pressure?

Past threads have documented a drop in oil pressure with hot oil and, in particular, long right hand corners. I experienced this on the street (mountain roads) and, being alarmed, upgraded to the X51 oil pan. On a recent drive, again on the street with hot oil, I still see this drop. I am talking about 4000 RPM and seeing a brief drop from 4 BAR to 2 BAR. So does anyone have a theory about what is really happening to result in the 2 BAR reading? Seems to me if it is really oil starvation at the pickup, it should drop to zero. Does it do this but the gauge is too slow to show it? And what about the RH turn thing? Does it do it on LH turns too and you can't see it with hand/arm in the way of the sight line to the gauge or ??? Why would it only be a RH turn thing? Mostly trying to understand if this drop in pressure is actually harmful to the engine. And, assuming it is, what more can I do to prevent it? My car is so low that I don't think an extra capacity pan is an option due to clearance issues. Before you ask, Liqui Moly 5W40 and yes, sump is full. Sumitomo tires.

Did you do the full X51 kit with extended pickup tube? Good discussion on the X51 oil pan and starvation issues here https://rennlist.com/forums/996-foru...d-baffles.html https://www.renntech.org/forums/topi...vation-issues/ http://support.lnengineering.com/201...m96m97-engine/ To LN Engineering - Charles @ LN Engineering has been a very great resource and sponsor for this forum. Charles, if you are reading this, all of the links on the above web page result in a 404 error (the links are broken). Just thought I would mention it. And another thought - did you upgrade to a LN spin on oil filter adapter with a full flow filter w/no bypass? Also upgrade the oil pressure relief valve and spring.

I installed the X51 lower plate with the improved baffle. No extended pickup because there is no change in depth or oil capacity. In fact, the only really visible difference is the addition of what I would call sneakage baffles to the X51. I do have both the 997 pressure relief upgrade and the LN spin on filter. So reading the first link, sounds like the cylinder head for 4-6 does not drain well (left side head, yes?) so on RH turns oil builds up there and doesn't drain well into the sump. Sounds like this is partly a capacity problem. Wonder what is happening with those folks who run the oil a little low at the track to avoid AOS issues?? I am still interested to know what is happening when the oil pressure dips but doesn't go to zero. I am afraid I already know - the engine has starved for oil momentarily. Rough on rod bearings if that is the case.

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What is probably happening is the engine is not starved for oil -- otherwise your post would have had an entirely different tone -- the oil just has some air in it and there is a bit of drop in oil pressure as this aerated oil is fed into the oil passages. There is a problem with the fact that the heads do not have a scavenge pump at both ends. Under extreme g-forces -- generally encountered on the track making a high speed turn -- a considerable amount of oil can collect ("puddle") under the camshaft cover away from the scavenge pump. I can't recall which side but it is the side with the pump at the back of the head. The combination of a sharp high speed turn coupled with initial braking really subjects the car to some high g-forces. This collecting of oil under the camshaft cover away from the scavenge pump lowers the oil level in the oil sump. There is still plenty of oil though but unfortunately it retains some air. The defoaming pots are not 100% efficient. Most of the time they work well enough that while there is some air in the oil because the engine is not using that much oil so by the time this aerated oil gets down to the sump pick up it has lost its load of air. But under severe usage with way more aeration of the oil taking place and couple this with the lowering of the oil level in the sump due to the above g-force induced oil puddling the pump ingests aerated oil. In some cases this has been observed in (non-Porsche) engines even while on the dyno when testing at high RPMs. Power falls off and after some investigation it was found at extremely high RPMs the oil level in the sump was falling low enough aerated oil was being fed to the engine. Rather surprisingly the bearings were ok but the hydraulic lifters partially colllapsed and enough to effect valve lift and timing and thus the engine lost power. In your case it would appear the engine needs a deeper sump with of course an extended oil pick up and suitable baffling. In the meantime run fresh oil. Oil as it is used gets contaminated with combustioni byproducts and these exacrebate the tendency of oil to foam. Fresh oll is more resistant to this. My auto tech buddies advised me to always show up at the track with fresh engine oil and I likewise advise you to do the same. Run the oil level at the max bar/line when measured hot. Use an approved oil of the right viscosity grade (and additive package).

This is why some prefer using a deep sump+extended 997 pickup+baffles. LN sell the Bilt Racing Deep sump kit that does this.There are others -like Mantis. http://lnengineering.com/2qt-deep-su...51-baffle.html Or Pedro has one. As a separate issue there has been much discussion of anti-foam oil selection. The conclusion was that JGDT40 was fine unless you do wild Tracking.

Hi , All , the Mantis 2L sump fits under the stock plastic under body. here's some data to backup the performance of the Mantis sump. The Mantis sump has been developed since 2006, used on our PWC/PCA Race Cayman, this our 3rd and latest design. The only one with a windage tray.

If the problem is air being combined with oil that is causing the drop in pressure, then I would not just be concerned about lifters. I would think that any air between the bearings could result in bearing damage over time. Hydrodynamic barriers only really work well if it's a liquid, but having air in there seems like the bearing surfaces could touch.

So if I wanted to use my 996.1 for HPDE days what's the solution? Lots of price points here. LN engineering has 0.5 qt extenders to 2qt sump add ins with baffles. Seems the mantis falls between the two in size and price. Should the x51 baffle be used instead too? 0.5 plus x51 enough? Or do you need more sump capacity for longer turns? even with the mantis the oil pressure chart shows a few large dips.

You've verified that the sender is in no way responsible for the occasional errant readings? I have been driving my 996 on mountain roads 8 months out of the year (~500 miles of mountain roads per month) for the past 4 years; I have yet to see an unanticipated oil pressure change like you describe. For the sake of argument, what I'd call a sweeper (like the front straight at Fontana) does not exist on any street I drive. The roads I drive have extensive on- and off-camber turns lasting 5-10 seconds; going uphill, the car is seldom below 4K RPM. My favorite run is a 45.5 mile stretch I can do in a little over 33 minutes in the 996 (uphill). Downhill is slower due to increased death potential.

I had some sender issues in the past. Cruising along steady speed and the pressure would occasionally become unstable - dip down a little and back up. Replaced sender and this is now cured. I doubt it is the sender because it doesn't behave oddly at any time now. On the mountain roads, a couple of miles of steady uphill climb heats up the oil, then a few 7/10s RH turns and I see the dip in pressure. Doesn't last long. First instance, and what got me into the X51 pan, was this road, running South to North which is the steeper uphill grade. It doesn't take a long sweeper. Medium does it.

from what i've seen, hard on the brakes right before turn in definitely leads to starvation and pressure drop. I'm doing a 2qt deep sump with horizontal baffle and EBS racing vertical baffle to try to combat the problem at the track

I experienced the drop in oil pressure on a left hand sweeper at Blackhawk Farms race track. And I have to say if I didn't read all about this before I went to the track, I wouldn't of been looking at the oil pressure gauge on any of the turns.....oh so distracting when trying to corner. Why did they put it behind the steering wheel? Anyway.....yes, it would drop after about 5-6 laps...those first laps it would be fine, so oil temperature definitely has something to do with it. I just decided to get off track when that happened. And I was running DWS tires.....so nothing with a lot of stick. I have decided not to track my car in the future and just enjoy it as a street car.

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Yes. That is the nature of driving the good roads near me. Stab the brakes and toss it into the turn. And many turns are more than 90 degrees so you are in the corner for a while.

Its is indeed fun to pamper and buy accessories for our babies. BUT, for street driving on street tires, you will never develop enough G-force to oil starve the engine. Your tires will give out first, ending in either a slide, a drift, or a spin. The brief drop in pressure has nothing to do with oil starvation. Now, if you put on racing slicks then drive at the limit on a long right hand turn, say at the high bank turns of the Indianapolis raceway, then yes, oil starvation can be an issue.

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Yeah, this is where I was going as well. I'm not suggesting that OP is not a more capable driver than I am. All I can say is that on UHP summer tires on hot roads, I haven't seen what he's seeing. The car came with M1; I switched within it over to TOTAL Quartz Energy 9000 5W40. For the past year or two I've been running DT40. I used filter cartridges for the first couple of years and switched to the spin-on filters when I took the JG plunge. I haven't seen any errant readings from the oil pressure gauge, and I try to scan the gauges pretty much constantly.

I was hoping to blame this issue on how amazingly quick I am in the car, but then someone would chide me about the public road thing. My oil pressure does dip in hard RH turns when the oil is hot. Whether that is oil starvation, aerated oil or ??, I don't know. That is what I am trying to learn with this thread. I probably should study where the pressure gauge gets its reading with respect to the engine bearings to help determine the possible effects. I don't much care about a momentary loss of oil flow or delivery of aerated oil to the lifters, but if the gauge is actually telling me that these events are happening at the bearings, that is an issue.

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There you go. If it were simply the G-forces, it would have happened on the first few laps, so there must be something going on with the oil - temperature-related - that's a contributing factor. Here's a link: http://www.elephantracing.com/techtopic/oiltemperature.htm

For what it's worth, I Googled this issue and read a bunch of Corvette and Camero owners, some BMW folks, and a lotus all saying the same thing. It's always after many laps, maybe 15-20 mins on the track, and many times sweeping right hand turns. It seems like there's a common thread here with many different cars having this issue. For those that have oil pressure that returns to normal after the long sweeping turn, it sounds like an oil delivery/pickup problem. But for those that have low oil pressure stay low even after pulling off the track and then report normal pressure after the engine has been off for some time, that sounds like foaming and/or temperature issue to me.

I did look at the oil flow diagram and it appears to me that whatever you see happening at the gauge has already happened everywhere else in the engine. It is after (or possibly in parallel with) the gallery that feeds the crankshaft and the lifters.

I'm going through the same thing on my 99 3.4 Cab 70k miles. I have only had the car 6 months and it was fine all winter but when the temperature got up I noticed the drop in psi on hard turns on the street. I have a 99 3.4 Coupe with 160k miles that does not do this. I can even make it do this going straight down the highway by snapping the steering wheel. I have replaced the sump baffle ( it had a deformed rubber door) , pulled the oil pump relief spring and piston and measured it (OK) , changed oil filter, changed oil sender unit. No effect on it. I'm thinking aeration of the oil also. Next I think I will pull the in-sump AOS's off and disassemble them, there is something weird going on. This car was overheated before I got it so I'm thinking it could have damaged the AOS's in the sump. It's the strangest thing I have seen in a while. Has your car been overheated at any point?

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I have only had the car for the last 8000 miles but no overheating that I know about. [[/QUOTE]

That you've had two 99's and they behave(d) differently makes my head hurt.

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Yea...It's beginning to make my head hurt also !..lol I have 2 99 996's a Coupe and a Cab also an 02 986s

Well, after my track event at Road America on Friday, I can report that I also experienced the drop in oil pressure on the long sweeping turn know as Carousel (turn 9). I take that turn at about 70mph-74mph, in gear 3, and on street tires (Michelin AS33+). I was running 15w-50 Mobil 1 for my track event, which meant I was at 5 bar pretty much everywhere except Carousel, where I saw it drop to 4 and if I was really pushing that turn, 3.5. My water temps were between 102-107C the whole day, and mostly were 104-105 (221F), which means that my oil could have been 220-240F. I was able to reproduce this easily and not after many laps. It happened on the first as well as the last lap.

The Carousel at Road America is a harsh test so not surprised. Your pressure is higher than mine, which normally runs at around 4 BAR when really warmed up and yours does not drop as low as mine either.

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Yeah, my car for some reason has quite high oil pressure. I'm pegged at over 5 bar on any oil and any RPM above 1500 even when warm. I was reluctant to run 15-50 at the track and probably would have been fine with 0-40, but I probably gained 0.5-1.0 bar switching to this for the track. As as much as Carousel might appear harsh, I was on all-season tires, not really pushing it too hard. There are plenty of on-ramps by me that I'm sure I could get the needle to dip on. I will try this one day and report back and after driving the car normally.

Another data point. I was at Pocono this weekend and the same thing was happening to me. First 10 minutes, everything is fine. Under throttle, I'm between 4-5 bar, regardless of if I am going straight, braking or turning. At about the 10 minute mark, pressure would dip to between 2-3 in the turns, come back up to 4 in the straights. I would come off the track at this point, by the time I made it to the pits, it was back up between 4-5 under throttle. When it is driven on the street, this never occurs. I have the FVD baffled deep sump, with extended pick-up. Spin on filter, running XP9. I have about 400 miles on the oil, so it could have been getting to the end of its life. One other data point, I was running Dunlop Direzza Star Tec IIs. So a sticky tire, but not a slick. I plan to drop the pan, just to make sure there is no debris in the pick-up (I just installed the pan, and perhaps there is some stray gasket material that got released). I'll change the oil and filter (send it to Blackstone), and I will monitor at the next event. If it continues to be a problem, I will dig deeper.

For the record, oil starvation at the track is a documented reality, although there is still some arguing by certain folks about the underlying cause(s). This much talk about oil pressure drop issues on the street w/ street tires, though, is news to me.

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If it can happen on the track with street tires and is repeatable by many different owners, then I can totally see how it would be possible on the street with some spirited driving, especially if the roads are twisty, the temps are high, and/or if elevation is a factor. I'm guessing track folks are just more aware of their pressures than regular drivers. And I'm guessing that some beginner track folks are slower on the track than others on the street.

Not arguing - but I'm also a little disheartened that a couple of people have chimed in to seemingly confirm that oiling issues can happen during "normal" street driving. Even if OP is a GOD behind the wheel, ANY car that shows oiling issues under normal circumstances is a disappointment. It really sucks when the car is a 911, and not a Daihatsu Charade or a Ford Festiva.

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Agree. For what it's worth, oil starvation was always an issue with most American Muscle cars over the last 40 years. And apparently still an issue for many Vettes. But like you said, it's a Porsche, not a Nova

No manufacturer has an excuse to make an engine that sucks, but at least you can buy crate motors for a Chebby WITHOUT having to explain to Junior that if he wants to go to college, he'd better make friends with his Uncle Sam...

Well I have cured the oil pressure drop on hard turns on my 99 Cab. It was indeed oil foaming problem. After I had already replaced the sump baffle, oil pressure sender, oil filter, removed the oil pump relief vale and spring and checked it (ok), checked scavenge pumps orientation for proper direction,(ok) ( thinking the PO or their tech had installed them pumping backwards). check and dissembled the in-sump AOS's/swirl pots (ok), I switched oil from Pennzoil Ultra Euro Synthetic 5w40 (a40 approved)to Mobil 1 15w50 and the oil pressure is great !! and steady, no dips on hard turns. I test drove down the same road I had driven many times testing the erratic pressure. I don't know if the oil had gotten contaminated, lost some viscosity, or what but definitely was foaming. I usually run Mobil 1 Euro 0w40 and that's what is in my other 99 Coupe and 986s but I am quite relieved to get the pressure great again ! I was beginning to think it was going to end up being something sinister.

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This is interesting to me because I ran brand new 15-50 Mobil 1 on my track event and saw the drop in oil pressure. But I don't have any of the other mods that you have.

I went to High Planes Raceway in Colorado yesterday. Fresh 5w40 Motul 8100. I knew there was a sweeping right hander where people had reported loss of oil pressure in the M96 engines. The turn is actually famous for killing m96 engines, turn 11. Sure enough after maybe the third lap I would get a sharp loss of pressure, only once the oil was hot. It would come down bellow 2bar. I took her easy through there every time which sucked for so many reasons. Im sharing my experience because I also want to get to the bottom of this, Im going to keep tracking my car and I do not want to kill it or have to baby it on the track. High Planes Raceway The Boxster race cars are so aggressive on track, loved playing with them. I chased an M2 all day

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Yep, seems to affect a lot of these cars. Honestly, I doubt you'll be able to get to the bottom of this without having to perform a bunch of upgrades. I read that one of the cylinder heads has a scavenging pump located in a spot that doesn't help in high g-force turns. A dry-sump might be the solution.

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Its odd because some people with deep sumps and horizontsl baffles clsim they solved thr problem while others say the x51 baffle is enough while yet others have these parts and still see pressure drop, which having just installed a deep sump with horizontal and vertical baffles, is just baffling I mean you are literally giving the oil no damn place else to go. I velieve the head problem is that the scavenge pumps are on the front of one head and the back of the other so heavy braking causes the oil on one bank to sit in the front of the head (while the scavenge pump is in back). so now you got a bunch of oil in the head, you get on the gas coming out of a turn which then causes the lower oil level in the sump to slosh, and probably some degree of aeration as the swirl pots dont quite stip it, and you get pressure drop. Dry sump is the answer but at least for me its cheaper to buy 2 or even 3 used 2.5L motors for my boxster. Kinda sad that this is what its come to just to do some DE events.

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I think you have accurately assessed the oil pressure drop situation for the extreme situations involved in tracking the m96. Short of going to dry sump for the 5 chain motors there was a x51 kit for 3.4 that included a tandem scavenge for bank 2 and an external oil line from the front of head 2 to tandem scavenge pump for this reason. The 3.4 x51 was never available in the US and the kit is no longer available anywhere and VERY rare. The old racing rule of thumb on oil pressure is 10-12lbs of pressure per 1k RPM's. I had thought of a huge warning lite( 1 5/8 Autometer Pro-Lite) that is pressure/RPM relative that would warn these instances of pressure drop. I think they are happening a lot more than people realize. There are no pressure/RPM relative warning systems to get your attention to look at the pressure gauge.

Digesting all these thoughts and experiences, this issue makes at least some sense to me now. The position of the scavenge pump causes a mixture of oil and air to enter it during hard right hand corners and/or uphill situations. Being compressible, this air then causes a lower oil pressure at the pump discharge which we see on the gauge as a drop into the 2 bar range. Oil is still being delivered to the bearings but there could be pockets of air in the oil and this could cause some lubrication related engine issues. Some oils may tend to release the trapped air better than others which may explain why some experience an improvement when changing oil brands. The bottom line for me is don't track the 996 unless you have made improvements that address this issue. The extra scavenge pump sounds ideal but complicated and expensive. A deeper pan with more oil might give the oil a better chance to de-aerate. It probably isn't an oil baffle issue at all, which is why my X51 pan/baffle "upgrade" made no difference.

^^ Except one 996 guy on this forum has thousands of track miles on his stock 996 and has oil pressure drops and never had an engine issue. And many others tracked without mods, and presumably didn't have issues. So to me, this is strange - how can you have pressure drops caused by air and not have metal to metal contact.

You may be worrying unnecessarily as today it is showing 83F outside on the car and my pressure drops below the zero mark and showing just short of 200F on the temp gauge. I have not been speeding, driving pretty slow around the country lanes. I expect the oil temp to drop to about 180 if I keep my revs and speed higher letting the outside temp lower the oil temps. On a cold engine when starting my oil pressure shows 5bar for a long time until the oil gets warmer. Then if I want to show one or two bar I have to take the revs higher and travel faster in the wind so to speak. How come Porsche state that the 996 when it leaves the factory is street and track ready without any alterations in oil capacity or oil sump? I am baffled if you will excuse the pun.

I also have noticed that my oil pressure does drop about 1.5 bar (from about 4.5. to 3) when in a right hand clover leaf onramp stock sump, conti tires I've contemplated upgrading to the x51 sump, but haven't yet

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Your pressure drops below zero? I think that is cause for concern ! Porsche spec for warm oil pressure is above 4 bar at 4k RPM. Anything below 1 bar per 1k RPM I get a little uncomfortable, any drop below .7 bar per 1k RPM is not acceptable.

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Jim, I don't think you have that quite right yet. I believe (caveat: long time since I looked at the diagram...) that the oil pressure sender is upstream of the the scavenge pumps (Which simply return oil to the sump expeditiously, this being a flat engine where gravity is less help). Thus it's the main oil pump that is providing all the pressure that the sender is reporting. It does make sense that high G as you describe is causing a scavenge pump to starve, but to my mind that simply reduces the oil volume in the sump during the corner. The full modifications that came with the factory X51 engines seem to support this. I have a couple of questions for anyone who knows the answer(s): 1) Does excessively aerated oil "float" on top of un-aerated oil due to it's different density? Or is the oil in the sump largely homogeneous? 2) The 997 did away with the swirl pots to the best of my recollection. What were they replaced with? And is it backward compatible for M96 engines used in 996's? -Ian

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The scavenge pump does cause aeration of the oil that is returned to the sump, hence the use of the swirl pots on the outlets from the scavenge pumps.The 997 does not use the swirl pots (AOS"s Air Oil Separators), but rather just a strait pipe dump. Yes the strait pipe dumps are retro-compatable.The theory behind that is it's better to get the oil returned faster and let the de-aeration happen in the sump. Yes the aerated oil does "float" on top of the un-aerated oil, the problem stems from the lack of un-aerated oil in the sump due to increased oil flow from higher temperature causing thinner oil and more flow. When the flow is so great that the small amount of un-aerated oil is sucked up or sloshed over by g-forces, the aerated oil enters the pressure system. Seems like the things that can solve or help is lowering the oil temperature which will makes the oil thicker and slow the flow, use a thicker higher viscosity oil that will slow the flow, more oil in the system through deeper sump, more oil by use of a dry sump.

I guess I skipped a step in my description. I meant that the scavenge pump supplies an air/oil mix to the sump where the main oil pump picks it up and pumps this air/oil mixture to the bearings (and pressure sender). I understand that the pressure sender is after the main oil pump, not the scavenge pump. Thanks for clarifying this.

Way back when, I had an air cooled beetle as my first car. I beat hell out of that car, doing donuts in wet parking lots, catching air over RR tracks etc. then I built a bigger motor for it. As part of the build, I installed aVDO oil pressure gage to supplement the stock low oil pressure light. The sender was the same VDO unit that is used in the 996. Around sweeping on ramps, the oil pressure went to zero. Never did that with the stock engine. I pulled the sender and went back to the standard sender (without the second output for gage) and the oil light never came on. My my buddy had the same experience in his beetle with a bored out engine and VDO sender. Bottom line, the sender seemed to be the culprit. It could not handle even moderate g's without reading incorrectly. I wonder if that is contributing to the issue on the 996? Is the sender reacting to the g forces and malfunctioning? How can guys drive on track for extended miles with this problem and not have evidence of low oil pressure damage in their engines?

Well that's an interesting angle on this. I did replace the sender and only noticed this oil pressure drop afterwards. Hmmmm....

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Wow. That is great insight. I wonder how that can be tested? Has anyone ever hooked up another oil pressure sensor? As I noted earlier in the thread, this just started happening to me this year, after an engine swap. Never happened before. In my case, it starts happening after about 10 minutes on the track, after the oil is nice and hot. I have a deeper pan, and am running XP9. The last track event, when it was happening, as soon as I was out of the turn, it would go back up to between 4-5bar This past weekend, even when I was out of the turn, the needle would bounce up and down before it would go back to 4-5bar in the straight, kind of acting like a broken gauge. These cars are fun! To top it off, all of my oil pressure trouble shooting was rewarded with a blown AOS. This AOS made it 1600 miles, a factory Porsche part.

This is what LN recommends.

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I disagree on the ring compressor. I use photo paper with a bunch of rubber bands.

So I have a related question. Driving home from work I get off the highway after normal driving and when I get to a stop sign I occasionally get a low oil pressure warning. Oil is topped up and recently changed. Warmer weather but not scorching up here in the NE. A quick blip makes it go away. Normal? Thanks.

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AOS is the bain of my existence. I should bill NJMP for my mosquito killing services. At least its easier to change on my boxster. very frustrating.

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Yeah, I kept hearing your car/number called over the radio for your clouds. I stopped driving mine after it started. Now just need to figure out if I have time to change it before the Glen or if I need to pay someone to do it. At least it was under warranty.

same here, mine was new as well. I have a new one on the way. have you checked your scavenge pumps for the proper orientation? I was hoping that was my problem but I pulled it last night and it was oriented correctly and undamaged.

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I haven't yet, although it is a remanufactured motor from Porsche, that I do not think has ever been apart so they would have had to have been having a pretty bad day at the factory. I really do not want to have to add an accusump, but I really would like to be able to go out for more than 10 minutes for each run session. I know there are a ton of people that just ignore the drop in oil pressure, I'm just not willing to.

what sump/sump mods do you have?

How high are your oil levels with the AOS smoking?

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The FVD Brombacher one: https://www.fvd.net/us-en/FVD2079880...otorsport.html What's so odd is that I had no issue last year on the old motor with this pan, and no issues at Shennandoah with the new motor and this pan (and I was watching everything like a hawk at Shennandoah since it was my first event since replacing the motor). I have changed nothing (other than changing the oil, but the oil type was the same Joe Gibbs XP9).

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Using the electronic level, I started out between 1 bar above low, and one bar below half. I added a bit more (so it was 1-2 bars above half) to see if to would clear up the oil pressure issue. It did not, but the AOS went the session after adding more oil. I will never run it with it over the half mark again.

thats so odd that it was fine at shenendoah given the carousel and the crazy elevation changes. What turns were causing your pressure drop? I'm guessing the light bulb. I have the Tune RS sump spacer and I got that one specifically for the horizontal baffle. I don't think the FVD has that. Unless you are just developing higher Gs as you get more experienced. Did you use the pressure sender from your old motor? would be interesting to see if you don't and then put the old one back on whether the drop goes away.

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Fair enough, I figured it was worth mentioning to keep it halfway between high & low. Never had mine smoke under hard driving or at HPDE, but have read Slakker's thread where he worked through some smoking issues by keeping a lower oil level.

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At lightning, it was every turn. I am using the pressure sensor from the new motor. I think I am going to swap it out with either the one from my old motor or a new one. It's a cheap enough thing to experiment with.

Accusump? http://www.accusump.com/ Picture 4 in pelican track prep http://www.pelicanparts.com/techarti...Track_Prep.htm

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Does your RPMs drop below a normal idle when you come in off the highway? If not, and a blip fixes the issue, that seems a bit strange to me. The oil pressure should be a function of RPM, and if the blip then settles down to the same RPM, the oil pressure should fall back down to the same too.

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Yes, looks like an accusump is in my future. It's just so odd that I had no issues last year and no issues the first event this year. It is possible that that I am just driving the car harder. I am still running street tires though. Was about to make the jump, but am waiting until I have the oil issue taken care of. My order of preparing a car is: 1. SAFETY 2. Reliability 3. Performance

Thanks murphyslaw. RPM's drop at the stop sign to ~800 or so when I get the warning. Seems like the sudden drop in engine speed causes it. I'll keep a closer eye on it on the way home today. It does stabilize and only happens after 30 plus minutes of sometimes spirited highway driving.

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What are the differences in your lap times if that were the case? Did you switch oil brands from then until now?

haven't read the whole thread but have you tried a new sensor?

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Been using the same oil Joe Gibbs XP9. I have never timed myself, but this year I am catching people I was never able to catch before. Last year was the first year in the 911 (was E36 M3 before that), that it took me most of the season to feel comfortable in the car.

Ok I just stumbled onto some facts about oil foaming that may or may not contribute to the oil pressure drop/ oil foaming problem on the m96 engine. I discovered that the Ford PowerStroke engine had suffered problems with oil foaming due to a chemical reaction with the RTV silicone used on the oil pan. Certain year models of the PowerStroke uses oil pressure to activate the injectors and the oil foaming after @3k miles would cause lose of power or missfire(no main oil pressure problems apparently the oil level of un-aerated oil was still satisfactory to supply the main oil pump). The cure was to add anti-foaming additives or change oil early to eliminate the foaming, The reaction of the RTV with the oil would lessen after time and ageing of the RTV. The "special" RTV that was designed that would NOT react with the oil is a Alkoxy cure type of RTV.(( part # Ford- F5TZ-19G204-AB, Motorcraft TA-31, IH- 1830858C1,Wacker (pronounced vahker) - T-442)) . According to my research there are 5 common types of RTV silicone that are categorized by the by-products of the curing process, namely Alkoxy, Acetic , Oxime, Acetone, Amine. See attached link for more info on RTV types.[URL=http://www.intertronics.co.uk/articles/tb008.htm Just for reference the Loctite 5900 is of the Oxime type, the Permatex Ultra Grey, Blue, Black, Copper is also of the Oxime type. According to what I found the only type that does NOT react with the metal or oil is the Alkoxy type. I had just happen to use the Permatex Ultra Grey on my 1999 Cab recently for the oil pan and head covers. I normally always use Loctite 5900 (which is still an Oxime type) but since I have been retired it would take a special trip to get it so I used what was handy. It would be interesting to know if some of you that have this issue were using the Permatex RTV or recently used Locktite 5900? There needs to be more data to see if this has any effect on the oil foaming issue that we have on the m96, but it sure did cause a fuss in the PowerStroke World. The PowerStroke placed unusual demands on the oil for anti-foaming and our m96 engine with the high revs and 2 scavenge pumps place an unusual demand on it. We know that different brands of oil have different anti-foaming abilities ( more silicone for anti-foamng). I will know if my choice of RTV has contributed to this IF my oil pressure problem returns. Thoughts??

^^ Interesting. My car, to my knowledge, has not had anything removed or replaced, so if foaming is due to silicon or other adhesives, it must be what the factory used. There was one other person here on this forum that continued to have loss of oil pressure in turns and they finally got rid of it with a specific brand of oil.

A data point for you. I am having the issue while using 5900. New pan install and new oil install and it is happening.

Quotes source post: 14312450

Ditto

It's quite simply that the oil pump is sucking air because there is no dry sump system in place, along with enough proper scavenging, combined with g-force loading and aeration of the oil. Putting in a better oil pan, with a better pickup, changing the scavenging in the heads, Accusump, and running different oil can all help, but nothing is guaranteed to fix the problem. I'm guessing 95% of Porsche 996 owners (and this affects some Boxsters too) don't drive on the track, and the ones that do, probably have some symptoms or issues, but don't notice it or don't have a failure because of it. That leaves less than 1%, which means that track folks are already doing all sorts of upgrades to thier cars to make them dutifully track proper. In the old days, oil and cooling systems were part of the car that would almost certainly need to be upgraded for serious track duty, even when using a sports car that was well built. I think we have come to expect more from a 996 than it was really meant for. For the track duty 911s, Porsche wanted us to buy GT3s and such. The old days of carrying over a dry-sump oiling system from a race car to the production version of the car was meant to actually save money by not having multiple designs for relatively low-production numbers. Now the Porsche made several tens of hundreds of 986/996 models, the opposite is true - it saves more money to make street versions that don't need to be robust on the track due to scale.

Quotes source post: 14487510

^^^ true, the only thing that will stop the issue in my opinion is a dry sump. Short of a dry sump one must do every thing they can to lessen the problem. After finding that Loctite 5900 and Permatex Ultra Grey/Blue/Black/Red and MOST RTV's are of the Oxime cure type that will react with oil and metals to promote foaming. The lesser common Alkoxy type does NOT encourage foaming. So if your fighting a pressure drop/foaming issue and are doing all you can, include your choice of RTV in the mix. Loctite 5970 is a good choice of RTV,it is the Alkoxy type and is used by Audi. Here is a list of Locktite RTV's. I found it interesting that several were described as "low foaming" or "reduced foaming", but I didn't see any described as "high foaming"??lol http://www.na.henkel-adhesives.com/u...o_Ind_2627.pdf

Detailed thread from a racing team that uses m96s alongside a custom dry-sump system: https://rennlist.com/forums/racing-a...mp-system.html and a field report - 24hr race :O

RE: deep sump systems & 996 availability

Quotes source post: 14493033

While I have no doubt that a well designed dry sump will solve the oil pressure drop issues, It's just not practical for the most people, it only makes sense for a dedicated track/race car, which can live without A/C which he states must be done. Not just with the associated cost, the space limits on a unmolested Porsche 996 do not allow for a 3 gallon dry sump tank, along with a dry sump pump, drive , lines, ect. but mainly the 3 gallon tank. He doesn't say exactly what size tank he uses but a 3 gallon is the norm, and that is filled to the 2/3 oil/air which means that only 8 quarts oil is used in the 3 gallon tank, which is less than the factory" integrated dry (wet) sump" with over 9 quarts. My question is where is all that oil, and what is it doing? Probably a quart and a half in each head under most conditions waiting to be pumped to the sump via scavenge pump, probably another 3/4 -1 quart on the crank/rods/IMS/chains/lower cylinders/carrier, slowly dripping back to the sump.The other 5-6 quarts are in the sump. So what's going on in the sump? With all the sump designs/baffles G force oil control, that have already been done and tried, and as he states "do not help". only the deeper sump (with even more oil) help, why is that? My theory is that it is not a G force/slosh problem at all, the G force/ slosh just uncovers the problem. I think the problem is simply foam/aeration of 2-3 quarts of the 5-6 quarts available. With only 2-4 quarts of un-aerated oil, G force/slosh WILL show a pressure drop, even on the street ( which a lot of people are seeing). There is still plenty of oil there, it's just that once the 2-4 quarts of SOLID oil sloshes to the side, the main oil pump draws in SPONGY oil. So what can be done? Of course an external tall slim dry sump tank can make efficient use of the 2-4 quarts of un-aerated oil and control the G force/slosh much better while the aerated/foam has time to defoam. I just can't convince myself that we have around 10 quarts of oil in the m96 engine and can't deliver a good constant oil supply without resorting to an external reservoir and pump. The crankshaft and complete rotation assembly is well separated from the sump so windage aeration isn't bad. The aeration/foaming must be coming from the scavenge pumps. While writing this and thinking out loud, I have an idea that may greatly reduce the aeration/foaming in these engines. It will take me a week or two to put it together and test it. I'll report back !!

Agreed it's not practical for DE/Street use, just throwing it out there as the thread contains a lot of lessons learned. From what I've seen there are two effective strategies beyond hope & luck for tracking the m96. Raby's approach of using XP9 and not pushing the engine past its limits time-wise & a full on deep sump system from Mr. Cervelli & team. Admittedly, that leaves a wide chasm in terms of use patterns (short DE or full blown race setup). But it is what it is. Adapt & move on.

Quotes source post: 14493960

I agree^^ I have a hard time paying for a solution if I don't understand the failure mode. So, I am out to understand the failure mode. What causes the drop on oil pressure: foaming, lack of oil, some other unidentified cause? I used to be critical of Porsche for claiming "integrated dry sump" on the M96. After some thought, it makes some sense. As stat d by Porschetech, the rotating assemblies are effectively isolated from the sump. This makes the sump an integrated container for the oil. Mid the scaveng pumps are causing aeration, maybe a more effective de-Ariator is needed?