I don't believe so, that little ride was a lap killer as far as time goes.

 

BTW, oil fill for the data above was 11.75 QTS or XP9.

Still running the LN sump and baffle and the UAOS with the track drain back.

I attribute much of the slowness to getting familiar and gaining confidence in the new brake setup. The car also needs some chassis optimization to reap the benefits of the new dampers, bigger front splitter and the 275 front tires.

That all said, I don’t really have an answer for why the pressure looked better, the temps certainly seemed to be playing against that outcome.

Paul, thanks for picking up where you left off with the fabulous data summary ! The couple dips you mentioned, were they consistent every lap or anomalous to the lap we’re looking at ?

 

Jason, did you make any changes with water cooling system this year? Or same as last year?

 

Cooling system hardware unchanged. The new bumper may have an affect on airflow to rads but not something I can quantify.

 

I haven't studied the old data since last season in relation to new data, but oil pressure looked good, water temps were good, but oil temps moved from the 240s last season to low 250s on the footage but held.

Maybe one more late shift on the straights may help to contain oil temp? But may hurt speed due to aero and meaty tires? Dunno, just thinking out loud. It's always a balancing act.

 

Sorry I didn't look at this before blathering about it. The dips do occur on other laps but to varying degrees. Here are the 1st and last laps of the session with the worst dip lap. The overall change in pressure is the oil temp increase across the session. RPM's are at 4700. Lat G's are less than 1. Even with the dip down to 35psi, it's still well above the lows from last year. Overall G's are lower.


Here's the equivalent plot from last year. It shows the same drops. Not all laps have it, but like some other weird coincidences, it is amazingly consistent in lap position and car dynamics. I got nothin. Last burp of aerated oil? But how could that be so consistent?

 

If I was a betting man, this thread may evolve into a conversation on cooling this season as it pertains to oil pressure instability. It's the last piece of the puzzle that hasn't been fully quantified and solved for.

 

New dampers? Is there maybe less body roll that can explain the better oil pressure.

 

Sure, anything is possible.

But my best guess is that because Jason has done nothing to his engine and cooling, with the only variables being his new aero, brakes and suspension that would create a question on anybody's mind as to where is the "new" limit. As such, you don't attack the turn and braking areas as you did with your past set-up until you figure out where the limit is. As a result, your Gs are lower and you compensate by pushing the throttle harder and longer on the straights which creates more heating.

We have all been there until we get the set-up to our liking. Happened to me many times as I changed things. Even as simple as moving to a different set of tires that you never used before.

 

G`dday all from down here in NZ. First off thanks for the awesome R&D work being done by people on here, as well as the contributions from the like of Jake and Chris - it`s been very informative.

I`ve just read through the 55 (and counting) pages of this thread and figured I'd chime in with some observations and what i`m doing on our 2001 Carrera 4. My car has around 150k kms, Pilot Sport PS2 tyres (so not especially grippy), and I have observed mild oil pressure instability on tarmac rally touring stages (limited to 160km/hr) and track days.


Shameless pre-Targa pic

I know this, as I film in-car, and car review the oil pressure gauge against track geography and RPM / engine temperature. Never below 2.5 bar (~35 psi?) and generally on left hand bends following heavy braking. This has been observed with the current setup of an FVD deep sump, FVD low temperature thermostat, and a new genuine waterpump, with street oil (the Porsche Classic 996 oil or Motul). Anecdotally, the deep sump and slightly better cooling did improve observed minimum oil pressure by around .5 of a bar, but it`s still affected by the resultant G forces from braking and cornering. I`d have to concur with Jake`s observations about heat build-up in the oil, as it mirrors my experiences.

Following a delivery from Rosepassion, I now have the OEM return line to go with one of Martin`s (H2 Engineering) Dual Scavenge oil pumps, together with the OEM third radiator kit, sitting in the car to be fitted.

Rear face - really well machined


H2 Engineering scavenge pump

This is all being installed next week by my awesome mechanic, in advance of a PCNZ DE day at the start of August, and the Targa NZ South Island Tour in October. I know there has been a lot of conjecture about the dual scavenge pumps, so i figured I'd put my money where my mouth is and get one, fit it up, and see how it goes. I`ll circle back with the outcomes, which may be useful to the wider M96 community.

 

the show so far: I've gone through the Thompson races and pulled together the best laps in each outing to visually show how the oil pressure drops have changed over time. The oil quantity used and date of the race is at the bottom of the plot. All plots have the same Y-axis. The new Race Studio version doesn't manage Y axis labeling as well as the last version. It takes up alot of space.

This is close to the beginning: 1/4 full on the 996.2 dipstick, immediately after installing the UAOS due to blue smoke belching on the previous track. Blue smoke belching solved

Here are the next 2 races as oil level is being increased. Clearly the pressure drops are becoming less. The hard part is interpreting the effect of oil temperature on the drops. The black line is the oil temp. The 7/29 drops are clearly smaller than the 6/27 drops. The oil temp is quite a bit cooler as well. The improvement is likely due to both.


Significantly better than the first, 8/31 drops seem to be similar in magnitude, but look at the width of each drop, they are much narrower

This shows the personal best from last year and the first plot of this year. The newest plot is pretty amazing even with the hotter oil temperature. We could claim rusty driver, given it's the first of the season, but the time on this lap is the same or better than the laps shown(except PB), so the pressure drops are absolutely less.

Tomorrow I'll try to get the engine risk summary up. The hope is to show how the total time the engine is at risk has gone to zero. (until the new suspension and aerodynamics are worked out...) Stay tuned!

 

Engine Risk. Recall that first we create a mask that identifies any time where RPM's are higher than 4500 and throttle is more than 75%. Then we look for oil pressure Less Than certain values within those times.

This plot overlays 2 laps. The green is the fastest lap from June'21. The brownish(sorry bad color) is the fastest lap June'22. This lap is faster by 0.7s. The oil temp in the current lap is a little hotter. Each of the rows below the track data show the time/distance that the oil pressure is below the test value. The first time blips we see are below 35psi for June'21 lap. We know it is more than 25 but less than 35. There are 3 periods that violate the rule. The first risk for the current lap is between 40 and 45. It's funny that this location is the same as that weird drop out we discussed above in turn 9. In any case, the current lap shows a second blip show up on the 50 line. While more time gets added to the lap from June'21. No question the engine is much lower risk today. What pressure did we say we were concerned with? My brain isn't coming up with a number and I couldn't find one in the thread.


The primary thing that's been done to push this value up is to add oil, as allowed by the UAOS Track Drain Back. I think the next step is to add another 1/4 to 1/2 quart. We don't know the flow limit for the drain back, and the UAOS has a warning chime when it is full. Maybe it's not necessary if 40 to 45psi for the worst case drop is actually not a risk. There is no question how valuable the Drain Back has been.

 

What a cool way to look at it ! Very impressive Paul - A million thanks for taking the time to go through and create such an interesting way to review the data.

I think for my comfort level, I'll prob shoot for another increase for the next day I have a week from today, I haven't checked consumption yet from the previous day but if it looks as though there was no meaningful oil consumption, I will add in the 1/4 QT that will make for 12 and see what that gets us.

And to your point on the drainback, it is the singular mod that has kept this motor in the car, with the blow by I have, and how keeping oil out of the intake got harder and harder as I got faster, without it I would have either got fed up and went in another direction or it would have blown up if I ran it too low.

 

Paul, I think you need to read the thread over again. The primary things for getting where Zbomb is today is: Deep sump, scavenge pumps and more oil. It works like this: The deep sump lowers the pick up x inch below the oil level in the sump, creating extra buffer before it runs dry when the oil sloshes around. Fresh scavenge pumps makes sure that maximum oil is returned to the sump for critical situations, preventing/slowing down the sump from running dry. More oil gives more buffer in situations where the engine is pooling oil outside of the sump.

The question now is, can he safely keep filling oil until the pressure drops are gone or will this damage something? If you look at my investigation in post #49(https://rennlist.com/forums/996-foru...corners-4.html) , the running oil level is below minimum level if pressure drops happen below 1G lateral force.

 

The rule of thumb is 10 PSI per 1000 RPM. At 45 PSI as a minimum there should be no additional problems, provided the oil temp stays tolerable. The concern that I have is how much - if any - engine wear occurred before the oil pressure was secured with these mods.

The other concern I have is, if we have secured a suitable height of oil above the pump inlet why are there oil pressure drops at all? It would seem to me that if there is sufficient oil for the pump to ingest there ought to be no oil pressure drops. I suspect that the oil pump is still cavitating to an extent because there is not quite enough oil column to overcome the long suction tube. This would be very difficult to prove or disprove.

Regardless the improvement is substantial.