Oil pressure drops on race track in S corners

[KillerBMotorsport]

So based on what I've seen so far, at this point, my opinion is that the oiling system is functioning as it should. If it wasn't, there would be a glut of track guy issues, and we're just not seeing that on a scale that point to an inherent problem. Heck the silicone on the oil pickup seems to be more of an issue than this.

Can it be improved? Of course! We haven't got the point of installing sensors all over our FA24 BRZ to KNOW what's going on yet, but based on our knowledge I think it's highly probable that this feedback is a combination of normal and poor pressure sender location.

The OEM pressure switch location is horrible and will magnify pressure changes caused by AVCS. A sandwich adapter should be better, but I'd prefer to see something further from the filter and closer to the pump. My gut tells me you will see an overall pressure increase, especially at higher RPMs, but AVCS will still cause a flattish or slight drop in pressure at the upper RPMs, which is normal.

[KillerBMotorsport]

Someone mentioned minimum pressure, what should it be? At the pump outlet, it should be greater than 14psi IMO. I only have FA20 WRX data which has a different oiling system, oiling demand, rev range, AVCS strategy, and this was 8 years ago before we were measuring oil flow too, so it doesn't make for more than a theoretical hypothesis. I do look forward to seeing where all of this leads!

[KillerBMotorsport]

Originally Posted by Blighty

Would something like an oil accumulator help reduce your risk?

IMO these devices only provide a false sense of security in the Suby community. They do not fix an actual issue, meet the flow demands of and EJ/FA engine when activated, and 'recharge' (causing an additional pressure drop) when the engine is under full load after corner exit.

Accumulators are great at dampening (how they were initially used decades ago) the oil pump's pressure variations if they are run open. Difficult to see unless you have decent sensor and ECU capabilities like with scientific capabilities or a Motec ECU. The oscillations can coincide with combustion events where load on the rod and main bearings spikes. So, if you can increase the low point pump oscillation you theoretically provide better oil supply at that crank angle. On some engines and performance level improving that condition can add life to the oil and engine. With the FA's 11 tooth gerotor, two combustion events per RPM, and relatively low power output, the pump oscillations seen are very small and inconsequential. to bearing oiling. They are also great at priming a freshly installed turbo, if you change them frequently for different stages and events, which I've never even heard of in BRZ/86 community.

[dragoontwo]

Originally Posted by KillerBMotorsport

The OEM pressure switch location is horrible and will magnify pressure changes caused by AVCS. A sandwich adapter should be better, but I'd prefer to see something further from the filter and closer to the pump. My gut tells me you will see an overall pressure increase, especially at higher RPMs, but AVCS will still cause a flattish or slight drop in pressure at the upper RPMs, which is normal.

About where on this diagram?

[dragoontwo]

It appears that the OEM pressure switch gets hit after the oil goes to the left hand head from the filter outlet. It looks like the easiest way would to catch it with a sandwich plate before it goes through the cooler.

[KillerBMotorsport]

Here ya go...

That schematic is correct, but edited for simplicity

[dragoontwo]

Originally Posted by KillerBMotorsport

Here ya go...

That schematic is correct, but edited for simplicity

Take it up with Subaru lol. It would seem that we are in agreement though. Now to try to find a slim plate that can fit under the cooler.

[Dzmitry]

Originally Posted by KillerBMotorsport

So we know a couple of things about the FA engines that are different from previous Suby engines. One is that the ECU is tied into oil temps. So, to the tuners out there, how is the oil temp feedback affecting output variables? We also know AVCS changes ~5,000 RPMs and it causes a pressure drop. Pressure should stay relatively flat to slight decrease under WOT load through the upper RPMs. Visualization credit here to Nissanfanatic. Not looking at the pressure numbers, that plot is normal for pretty much all Suby AVCS engines.

Ok, so does AVCS only start kicking in once fully warmed up (around 200-210F)? Because that data is not consistent when it comes to oil temps of 185F as you can see, where pressure continues to rise with increasing RPM.

[nissanfanatic]

Originally Posted by Dzmitry

Ok, so does AVCS only start kicking in once fully warmed up (around 200-210F)? Because that data is not consistent when it comes to oil temps of 185F as you can see, where pressure continues to rise with increasing RPM.

@Dzmitry was the data collected with the engine under full load for each of the data points you posted (obv excluding 800/2000 RPM)? Or, inverse, was each of them collected while free revving the engine?

Wondering how AVCS behaves under varying load...

[KillerBMotorsport]

Originally Posted by Dzmitry

Ok, so does AVCS only start kicking in once fully warmed up (around 200-210F)? Because that data is not consistent when it comes to oil temps of 185F as you can see, where pressure continues to rise with increasing RPM.

Agreed, but this is a better question for a tuner who has access to the ECU tuning tables.

[KillerBMotorsport]

Originally Posted by nissanfanatic

[MENTION=169282]
Wondering how AVCS behaves under varying load...

It's different under load and not. The oil pressure plot is very different when free revving. If the FA24 follows the FA20 (highly probably), you'll also have higher oil flow rates under load vs not under load, because under load a certain amount of flow is passing through AVCS. The additional flow demand is what causes the pressure to plateau and drop some after 5,000 RPMs.

[Blighty]

Originally Posted by KillerBMotorsport

IMO these devices only provide a false sense of security in the Suby community. They do not fix an actual issue, meet the flow demands of and EJ/FA engine when activated, and 'recharge' (causing an additional pressure drop) when the engine is under full load after corner exit.

Yeah I've seen a few conversations about them, but its potentially a cheap enough solution to do some testing with, as the dips into single figures do seem transient enough that the fill event wouldnt just give you another single digit psi.

[KillerBMotorsport]

Originally Posted by Blighty

Yeah I've seen a few conversations about them, but its potentially a cheap enough solution to do some testing with, as the dips into single figures do seem transient enough that the fill event wouldnt just give you another single digit psi.

Maybe. Consider this... The starvation issue is nearly always on breaking or steady right turns, and cresting right turns. Both have lite throttle applications if any. Loosing oil pressure at these times is not nearly as consequential and losing it under full load at corner exit when recharge occurs. You have to pick your poison here, but I will always choose lower oil pressure with no/low load over lower oil pressure under full load. Reassuring to see higher end sports cars with variable flow oil pumps doing the same; dropping pressure at throttle lift and no-to-light loads.

I would highly recommend any testing you do, be in a controlled environment, not on-track.

[KillerBMotorsport]

just took these pics this morning, for those interested in tapping locations. Plenty thick enough for tapping a 1/8 NPT or PT threads. These are two options depending on the sensor size and access capabilities...