Oil pressure drops on race track in S corners

[zeroomega]

Originally Posted by KillerBMotorsport

If you're getting it from the display, someone here posted some data about it being purposely skewed. Why is anyone's guess.

Yes, very familiar with the OEM setup. It's terrible, lol. If you're at a point where you're tracking regularly and considering an oil cooler, a dedicated oil temp gauge should be in use.

As far as taking temps from the sump, we carry a bunch of adapters specifically for that purpose.

I have JR oil cooler in place already. 250F temperature is what I see in a 100F day and push continuously for 20mins. Without the oil cooler I guess I can push this car beyond 270F in the same condition.

I have friend put a dedicate oil temperature sensor in sandwich plate. We can cross check data with him to see if there is a big discrepancy. For now I am not too worried about OEM temperature reading to be inaccuracy. The pressure gauge doesn't lie anyway.

[KillerBMotorsport]

Originally Posted by zeroomega

I have JR oil cooler in place already.

I must have missed that tidbit of info. Now it makes more sense.

Originally Posted by zeroomega

For now I am not too worried about OEM temperature reading to be inaccuracy. The pressure gauge doesn't lie anyway.

Very true. The drop you're experiencing is interesting to say the least. Curious, what size lines are on the JR cooler?

[zeroomega]

Originally Posted by KillerBMotorsport

I must have missed that tidbit of info. Now it makes more sense.




Very true. The drop you're experiencing is interesting to say the least. Curious, what size lines are on the JR cooler?

JR Oil cooler kit uses 10AN Aeroquip FC598-10 hose (for GR86, but I think their other kit use the same hose). It has 0.63in ID and 0.91 ID. The ID seems to be slightly larger than common 10AN hoses (which we saw a average 3psi pressure advantage at same temperature compared to colorfitting kit using regular 10AN hose). I change the hose to Goodridge G-Line XF 910 hose with 0.63in ID and 0.82in OD because I uses a different hose routing and it needs a slightly shorter hose to avoid rubbing.

[KillerBMotorsport]

Originally Posted by zeroomega

JR Oil cooler kit uses 10AN Aeroquip FC598-10 hose (for GR86, but I think their other kit use the same hose). It has 0.63in ID and 0.91 ID. The ID seems to be slightly larger than common 10AN hoses (which we saw a average 3psi pressure advantage at same temperature compared to colorfitting kit using regular 10AN hose). I change the hose to Goodridge G-Line XF 910 hose with 0.63in ID and 0.82in OD because I uses a different hose routing and it needs a slightly shorter hose to avoid rubbing.

-10 should be fine. That's the minimum size we recommend. Below that and you'll see a pressure drop.

I'm still stuck on the pressure drop you're seeing at temp. Odder knowing you've got a cooler, if anything that should stabilize pressure. It would be interesting to compare pre-cooler install to post-cooler pressures

[zeroomega]

Originally Posted by KillerBMotorsport

-10 should be fine. That's the minimum size we recommend. Below that and you'll see a pressure drop.

I'm still stuck on the pressure drop you're seeing at temp. Odder knowing you've got a cooler, if anything that should stabilize pressure. It would be interesting to compare pre-cooler install to post-cooler pressures

Well, my sandwich plate does have ports to put 1/8 NPT sensor at inlet and outlet. But GR86 hood is too low so the sensor will hit the hood when closed. I tried 90 degree adapter before, but without good way to keep the sensor in place, it might become a failure point so I relocate the sensor to the block.

My oil pressure/temperature data matches pretty well with TrackAndBuild's GR86 which has a colorfitting oil cooler. So I don't think its my setup issue. I will try to draw a pressure/temperature chart once I have more data. Right now most of my oil pressure data are collected in winter and oil temperature didn't go very high.

[nissanfanatic]

What would a/the theory be with the pressure drop under right hand corners being related to the oil cooler?

I'd be curious to see how the pressure drops track with RPM. IE, does 1G at, say, 3500rpm show a similar drop pattern to 1G at 6500...

[zeroomega]

Originally Posted by nissanfanatic

What would a/the theory be with the pressure drop under right hand corners being related to the oil cooler?

I'd be curious to see how the pressure drops track with RPM. IE, does 1G at, say, 3500rpm show a similar drop pattern to 1G at 6500...

Oil cooler has nothing to do with lateral g oil pressure drops. KillerBMotorsports is just concerned the pressure drops too much when oil temperature rises while I felt it is just normal oil viscosity change when oil temperature is higher, which is why I would like to try slightly higher oil weight in summer.

at 3500rpm the oil pump is pumping less amount of oil per sec than 6500rpm. We saw this pattern at Laguna Seca T4, where if we keep the car at 3rd gear redline, there will be brief oil pressure drop but if upshift to 4rd, the RPM will drop to around 5000 rpm and the oil pressure remains normal. So presumedly if you drive the car on track below 6k rpm, maybe you will not see any oil pressure drop at all, but then you will be much slower.

[nissanfanatic]

Originally Posted by zeroomega

Oil cooler has nothing to do with lateral g oil pressure drops. KillerBMotorsports is just concerned the pressure drops too much when oil temperature rises while I felt it is just normal oil viscosity change when oil temperature is higher, which is why I would like to try slightly higher oil weight in summer.

cool yea was just curious if there was something I was missing there.

Originally Posted by zeroomega

at 3500rpm the oil pump is pumping less amount of oil per sec than 6500rpm. We saw this pattern at Laguna Seca T4, where if we keep the car at 3rd gear redline, there will be brief oil pressure drop but if upshift to 4rd, the RPM will drop to around 5000 rpm and the oil pressure remains normal. So presumedly if you drive the car on track below 6k rpm, maybe you will not see any oil pressure drop at all, but then you will be much slower.

Yea, the reduction in rate of oil leaving the pan is what I was thinking. It would track with oil collecting elsewhere [heads] and not returning to the pan quick enough in relation to oil being pumped out of the pan. Def was not planning on tracking at less than 4000rpm as a strategy haha.

[Dzmitry]

Originally Posted by KillerBMotorsport

-10 should be fine. That's the minimum size we recommend. Below that and you'll see a pressure drop.

I'm still stuck on the pressure drop you're seeing at temp. Odder knowing you've got a cooler, if anything that should stabilize pressure. It would be interesting to compare pre-cooler install to post-cooler pressures

You had spoken about this briefly before with some good insight on why we may see oil pressure drop at high RPM. You are newer to the platform as I recall, so you may not exactly be aware of the pressure drop people discuss here and there. This has been very known since the first gen.

Typical data has shown that somewhere before 200-210F, you see fairly consistent pressure increase with an increase in RPM. Somewhere after these temps, you start to see a loss in pressure somewhere past 5-6K RPM. Throughout the years, many have posted their own data, but here's a quick one quoted from savagegeese on youtube:

STREET TEMPS
0W20 Redline

0w20 Redline 185F @ 800RPM 10PSI Oil Pressure
0w20 Redline 185F @ 2000RPM 35PSI Oil Pressure
0w20 Redline 185F @ 4000RPM 54PSI Oil Pressure
0w20 Redline 185F @ 7000RPM 65PSI Oil Pressure

10W30 Redline

10w30 Redline 185F @ 800RPM 19PSI Oil Pressure
10w30 Redline 185F @ 2000RPM 51PSI Oil Pressure
10w30 Redline 185F @ 4000RPM 65PSI Oil Pressure
10w30 Redline 185F @ 7000RPM 83PSI Oil Pressure

10W40 Redline

10w40 Redline 185F @ 800RPM 25PSI Oil Pressure
10w40 Redline 185F @ 2000RPM 64PSI Oil Pressure
10w40 Redline 185F @ 4000RPM 78PSI Oil Pressure
10w40 Redline 185F @ 7000RPM 91PSI Oil Pressure

TRACK TEMPS AFTER 9 LAPS @ 1 Minute 15 Seconds Per Lap
0W20 Redline

0w20 Redline 225F @ 800RPM 7PSI Oil Pressure
0w20 Redline 225F @ 2000RPM 30PSI Oil Pressure
0w20 Redline 225F @ 4000RPM 48PSI Oil Pressure
0w20 Redline 225F @ 7000RPM 43PSI Oil Pressure

10W30 Redline

10w30 Redline 245F @ 800RPM 7PSI Oil Pressure
10w30 Redline 245F @ 2000RPM 35PSI Oil Pressure
10w30 Redline 245F @ 4000RPM 52PSI Oil Pressure
10w30 Redline 245F @ 7000RPM 46PSI Oil Pressure

10W40 Redline (12 Laps)

10w40 Redline 265F @ 800RPM 8PSI Oil Pressure
10w40 Redline 265F @ 2000RPM 31PSI Oil Pressure
10w40 Redline 265F @ 4000RPM 55PSI Oil Pressure
10w40 Redline 265F @ 7000RPM 45PSI Oil Pressure

This type of data is what started the oil battles on this forum that have been repeatedly discussed. Ideas of cavitation and other theories came about to try and explain what is going on. I recall you mentioning cavitation being unlikely/impossible to be the case on our pumps.

Whatever the case, as stated by others, this is definitely a known concern from gen 1, and clearly has not changed (significantly) with gen 2. No one has really been able to identify whether this is normal or an actual problem and cause of some engines blowing. It has just been a red flag for a decade now and the reason that majority of owners tracking this vehicle opt to get an oil cooler.

Since you're quite experienced with Subarus and their oiling systems, I like to keep a close eye at your insight and thoughts on the meaning of all this.

[OkieSnuffBox]

I don't know the answer to this, so I'm just throwing it out there. There is a lot of data about oil pressure, at temp, pressure drop, etc.

Does anyone have any data on what would be considered the minimum acceptable oil pressure?

[nissanfanatic]

Originally Posted by Dzmitry

You had spoken about this briefly before with some good insight on why we may see oil pressure drop at high RPM. You are newer to the platform as I recall, so you may not exactly be aware of the pressure drop people discuss here and there. This has been very known since the first gen.

Typical data has shown that somewhere before 200-210F, you see fairly consistent pressure increase with an increase in RPM. Somewhere after these temps, you start to see a loss in pressure somewhere past 5-6K RPM. Throughout the years, many have posted their own data, but here's a quick one quoted from savagegeese on youtube:

STREET TEMPS
0W20 Redline

0w20 Redline 185F @ 800RPM 10PSI Oil Pressure
0w20 Redline 185F @ 2000RPM 35PSI Oil Pressure
0w20 Redline 185F @ 4000RPM 54PSI Oil Pressure
0w20 Redline 185F @ 7000RPM 65PSI Oil Pressure

10W30 Redline

10w30 Redline 185F @ 800RPM 19PSI Oil Pressure
10w30 Redline 185F @ 2000RPM 51PSI Oil Pressure
10w30 Redline 185F @ 4000RPM 65PSI Oil Pressure
10w30 Redline 185F @ 7000RPM 83PSI Oil Pressure

10W40 Redline

10w40 Redline 185F @ 800RPM 25PSI Oil Pressure
10w40 Redline 185F @ 2000RPM 64PSI Oil Pressure
10w40 Redline 185F @ 4000RPM 78PSI Oil Pressure
10w40 Redline 185F @ 7000RPM 91PSI Oil Pressure

TRACK TEMPS AFTER 9 LAPS @ 1 Minute 15 Seconds Per Lap
0W20 Redline

0w20 Redline 225F @ 800RPM 7PSI Oil Pressure
0w20 Redline 225F @ 2000RPM 30PSI Oil Pressure
0w20 Redline 225F @ 4000RPM 48PSI Oil Pressure
0w20 Redline 225F @ 7000RPM 43PSI Oil Pressure

10W30 Redline

10w30 Redline 245F @ 800RPM 7PSI Oil Pressure
10w30 Redline 245F @ 2000RPM 35PSI Oil Pressure
10w30 Redline 245F @ 4000RPM 52PSI Oil Pressure
10w30 Redline 245F @ 7000RPM 46PSI Oil Pressure

10W40 Redline (12 Laps)

10w40 Redline 265F @ 800RPM 8PSI Oil Pressure
10w40 Redline 265F @ 2000RPM 31PSI Oil Pressure
10w40 Redline 265F @ 4000RPM 55PSI Oil Pressure
10w40 Redline 265F @ 7000RPM 45PSI Oil Pressure

This type of data is what started the oil battles on this forum that have been repeatedly discussed. Ideas of cavitation and other theories came about to try and explain what is going on. I recall you mentioning cavitation being unlikely/impossible to be the case on our pumps.

Whatever the case, as stated by others, this is definitely a known concern from gen 1, and clearly has not changed (significantly) with gen 2. No one has really been able to identify whether this is normal or an actual problem and cause of some engines blowing. It has just been a red flag for a decade now and the reason that majority of owners tracking this vehicle opt to get an oil cooler.

Since you're quite experienced with Subarus and their oiling systems, I like to keep a close eye at your insight and thoughts on the meaning of all this.

Graph'd this data to visualize it:

[KillerBMotorsport]

Originally Posted by zeroomega

at 3500rpm the oil pump is pumping less amount of oil per sec than 6500rpm. We saw this pattern at Laguna Seca T4, where if we keep the car at 3rd gear redline, there will be brief oil pressure drop but if upshift to 4rd, the RPM will drop to around 5000 rpm and the oil pressure remains normal. So presumedly if you drive the car on track below 6k rpm, maybe you will not see any oil pressure drop at all, but then you will be much slower.

Couple of questions here... How many degrees of a turn is T4, and is it banked? In short, how many seconds are you IN the turn and at what lateral load? Sustained banked corners like at Daytona and the Nurburgring's Carousel are great examples of corners that eventually (at some level of experience, mods, etc.) causes problems with the Suby H4 engines.

[Blighty]

Would something like an oil accumulator help reduce your risk?

[KillerBMotorsport]

Originally Posted by Dzmitry

Typical data has shown that somewhere before 200-210F, you see fairly consistent pressure increase with an increase in RPM. Somewhere after these temps, you start to see a loss in pressure somewhere past 5-6K RPM.

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.

Originally Posted by Dzmitry

This type of data is what started the oil battles on this forum that have been repeatedly discussed. Ideas of cavitation and other theories came about to try and explain what is going on. I recall you mentioning cavitation being unlikely/impossible to be the case on our pumps.

Thanks so much for the data!

Correct, I have said that. The pump itself will NOT cavitate, it's not one of the characteristics of a positive displacement pump design. Same design is used on much higher reving engines, including motorcycle engines; some that rev to 16,000 RPMs. The problem that CAN occur is aeration from the pump's bypass valve. Given the design, pump output/RPMs, I don't see this as a possibility, especially below 7,000 RPMs. Another indicator that there's not cavitation is that the higher weight oils, and lower temp data, would have feedback that is misaligned from the others, and that posted data doesn't show that. That data looks proportionally correct across the board.

Originally Posted by Dzmitry

Since you're quite experienced with Subarus and their oiling systems, I like to keep a close eye at your insight and thoughts on the meaning of all this.

Thanks! We are certainly Subay oiling nerds and have collected far more data than anyone else out there that I know of. Knowledge is a never-ending battle!