Oil pressure drops on race track in S corners

[NoHaveMSG]

Originally Posted by Spektyr

This is probably too simple a solution to work, but most engines aren't hurt by a little excess oil volume. Too much is obviously bad, but half a quart more than "full" won't damage an FA24 in normal driving.

Would that hold true in track driving and if so, would that maybe add a little extra time in those corners before the oil gets too low?

You can go up a full quart on the FA20 no problem. I wouldn't doubt the FA24 is any different. The crank is way above the oil pan. There is actually a sub oil pan assembly between the pan and the crank that is 2-3 inches thick.

[zeroomega]

Originally Posted by Spektyr

This is probably too simple a solution to work, but most engines aren't hurt by a little excess oil volume. Too much is obviously bad, but half a quart more than "full" won't damage an FA24 in normal driving.

Would that hold true in track driving and if so, would that maybe add a little extra time in those corners before the oil gets too low?

I sometimes overfill the oil by 0.3qt during oil change, because the dipstick is just not very accurate. I didn't see any noticeable difference in logged oil pressure. I did't try 0.5qt overfill since it is not very far from 0.3qt. I am hesitate to go for 1 qt overfill. If someone tried it on the track with logged pressure and UOA please let me know.

[KillerBMotorsport]

Originally Posted by zeroomega

Thanks for your insight.

Of course! We love forums just for these kinds of things!

Originally Posted by zeroomega

In our club, one guy runs 10w60 (the original spec oil weight for Japanese GT86 cup cars) for 16 trackdays without changing it. The UOA data looks pretty good.

I saw a FB post recently with 10w-60 UOA data. The data wasn't clean, but I wouldn't run it based on that final 10w-60 report. The iron wear was way too high for my liking. Could be from MUCH too thick oil on cold start not getting to where it needs to be. Or, too thick and not getting sufficient oiling to the top ring. I always recommend moving incrementally from the MFG's recommended oil type with at least a couple (ideally 3) samples of each. This way there is less environmental and conditional impact across the averages for each oil. Plus, it takes several oil changes to reduce contamination from the previous oil type, to where the impact on the results is minimal.

Originally Posted by zeroomega

With 250F oil temperature, the pressure logged from post oil filter position is start dropping below 45psi at 7k rpm. At daily drive 210F oil temperature, this number is more closer to 70psi.

Something else is at play here. Going from 210°-250° should not cause anywhere near that kind of pressure drop. This sounds more like high temperature internal bleeding, where a rubber seal starts letting oil past once it gets hot enough.

Originally Posted by zeroomega

Also Subaru factory backed GT300 BRZ racecar uses dry sump system as well. This is an old article though, the Subaru's latest iteration of GT300 car now uses FA engines and gen2 body styles now. I see this as a signal that they knew the engine oiling is a weakness at circuit racing condition and beefed it up accordingly.

This is a multi-hundred thousand dollar dedicated track car. Not to mention the team of engineers, techs, spare engines, transmissions, tractor trailers (yes, several), etc., that support it. It's like comparing apples to a bottle of tequilla Teams like this place no value on what it costs to shave a few tenths off a lap time. As much as I love Subaru, for anyone with THIS kind of budget I'd recommend another platform for sure! From my knowledge, a DS system is used because they significantly lower (and push back) the engine in the chassis (on a custom engine cradle of course). Moving the CG has a profound effect on handling performance.

I don't think they added a DS because it's a weakness of the OEM oiling system. I think they did it because they were building a specialized highly competitive track car and were changing everything anyway. If it needed it or not. At that level you don't test first, you install the best parts money can buy, and then test.


Here's a great read on oil, temps, and viscosities, for anyone interested...

https://penriteoil.com.au/knowledge-...-viscosity/180

[KillerBMotorsport]

Originally Posted by NoHaveMSG

You can go up a full quart on the FA20 no problem. I wouldn't doubt the FA24 is any different. The crank is way above the oil pan. There is actually a sub oil pan assembly between the pan and the crank that is 2-3 inches thick.

Correct. I posted how much oil is in the lower and upper pan somewhere in here, but don't recall off the top of my head.

The crank is far. On the dyno we've tested +1 quart and -1 quarts and there's zero difference. Although, that's on a chassis dyno, not flogging around a road course. Adding additional oil may or may not improve conditions, depending on the cause.

[KillerBMotorsport]

Originally Posted by zeroomega

I sometimes overfill the oil by 0.3qt during oil change, because the dipstick is just not very accurate. I didn't see any noticeable difference in logged oil pressure. I did't try 0.5qt overfill since it is not very far from 0.3qt. I am hesitate to go for 1 qt overfill. If someone tried it on the track with logged pressure and UOA please let me know.

I don't blame you. I too would be hesitant to go +1 quarts on track. You're adding to the probability that oil will overwhelm the PCV vents if lateral loads are high enough. On a moderately modified car that doesn't have a significant increase in power output, likely not an issue.

[zeroomega]

Originally Posted by KillerBMotorsport

Of course! We love forums just for these kinds of things!




I saw a FB post recently with 10w-60 UOA data. The data wasn't clean, but I wouldn't run it based on that final 10w-60 report. The iron wear was way too high for my liking. Could be from MUCH too thick oil on cold start not getting to where it needs to be. Or, too thick and not getting sufficient oiling to the top ring. I always recommend moving incrementally from the MFG's recommended oil type with at least a couple (ideally 3) samples of each. This way there is less environmental and conditional impact across the averages for each oil. Plus, it takes several oil changes to reduce contamination from the previous oil type, to where the impact on the results is minimal.




Something else is at play here. Going from 210°-250° should not cause anywhere near that kind of pressure drop. This sounds more like high temperature internal bleeding, where a rubber seal starts letting oil past once it gets hot enough.




This is a multi-hundred thousand dollar dedicated track car. Not to mention the team of engineers, techs, spare engines, transmissions, tractor trailers (yes, several), etc., that support it. It's like comparing apples to a bottle of tequilla Teams like this place no value on what it costs to shave a few tenths off a lap time. As much as I love Subaru, for anyone with THIS kind of budget I'd recommend another platform for sure! From my knowledge, a DS system is used because they significantly lower (and push back) the engine in the chassis (on a custom engine cradle of course). Moving the CG has a profound effect on handling performance.

I don't think they added a DS because it's a weakness of the OEM oiling system. I think they did it because they were building a specialized highly competitive track car and were changing everything anyway. If it needed it or not. At that level you don't test first, you install the best parts money can buy, and then test.


Here's a great read on oil, temps, and viscosities, for anyone interested...

https://penriteoil.com.au/knowledge-...-viscosity/180

I am not planning to use 10w60 anyway. Since my car is not trailered and does meet some street miles, though not much.

For the pressure change from 210F to 250F, internal bleeding or not, it still translates to the necessity of adequate oil cooling. And if it is caused by internal bleeding instead of just oil viscosity drop, we cannot fix it. With Setrab Series 9 15 rows oil cooler core, under 100F California summer, it is not rare to see oil temperature closes to 250F, unfortunately.

For dry sump system, I guess we cannot say the cause why Subaru add that to their race spec engine for sure unless their engineer claim it. But I think we can all agree it is a nice thing to have if we can have it :-). Whether or not boxer engine has an inherited oiling problem compared to a inline engine, the fact that FA20 and FA24 has oil pressure drop behavior under high G load doesn't change. Whether or not this oil pressure will become an issue depends on the engine tolerance and that is something we don't know. I prefer to play it safe, doing anything economically to mitigate the pressure drop instead of just wishing this engine can withstand single digit psi under high load.

I wish next gen 86 can have a Toyota inline engine. At least it will make service it easier.

[mycrors7]

Originally Posted by NoHaveMSG

You can go up a full quart on the FA20 no problem. I wouldn't doubt the FA24 is any different. The crank is way above the oil pan. There is actually a sub oil pan assembly between the pan and the crank that is 2-3 inches thick.

this^

on my old e36 m3(and pretty much any e36 m3 that tracks heavily with the stock s52), its common to just dump a whole quart of oil in before going on track. its gonna burn it off when vanos is active at high RPM(much like how vtec tends to eat through oil as well).

seems like i may end up doing half a quart before going on track and keeping an eye on it throughout the day.

[KillerBMotorsport]

Originally Posted by zeroomega

For the pressure change from 210F to 250F, internal bleeding or not, it still translates to the necessity of adequate oil cooling.

Maybe? At 250° you've still got a buffer, but that drop in pressure is concerning. If you hit 260° it's time for a cool down lap and to consider an oil cooling solution. At 250° peak I would save my money and not add the extra weight and potential leak points.

Would be nice to see a bit more data here. Where were the temps measured from? Timing cover or sump? There's generally a 20° difference between the two, with the sump being colder. There could be various reasons for this, but in motorsports, taking temps at the sump is the standard.

Originally Posted by zeroomega

I prefer to play it safe, doing anything economically to mitigate the pressure drop instead of just wishing this engine can withstand single digit psi under high load.

Agreed. We're working on it

Originally Posted by zeroomega

I wish next gen 86 can have a Toyota inline engine. At least it will make service it easier.

Careful what you wish for on this one!

[BioRebel]

I see a lot of people talking about going to 5w30 for track usage but I don't really get why. If you're trying to mitigate the oil being too thing at higher temps why increase the low end viscosity? Wouldn't 0w30/0w40 make more sense?


That being said, I agree that keeping the oil within operational temperatures is preferable to trying to guess what viscosity the engine likes at any given temperature. Looking @ the Jackson racing one since it keeps the conditioner, since I live in the NE I need that.

[nissanfanatic]

Originally Posted by BioRebel

I see a lot of people talking about going to 10w30 for track usage but I don't really get why. If you're trying to mitigate the oil being too thing at higher temps why increase the low end viscosity? Wouldn't 0w30/0w40 make more sense?


That being said, I agree that keeping the oil within operational temperatures is preferable to trying to guess what viscosity the engine likes at any given temperature. Looking @ the Jackson racing one since it keeps the conditioner, since I live in the NE I need that.

I honestly haven't see any 10w-30's that I'd care to run. I generally look for HTHS and other UOA to see how well the oil maintained viscosity, which gives me an idea of how often I'll be replacing it. I also just look at the viscosity range at the provided temperatures (there are a couple euro oils that spec in the 30w range, but are nearly 40w oils).

Multi-viscosity isn't a panacea though (with the exception of ester oils as they are naturally multigrade) as it is created through the use of polymer additives. Generally, more polymer additives = faster loss of viscosity (shearing) which is one of the top concerns esp in hard driving. IDK about you, but I'm less concerned with "year round" usage and more concerned with not having to change the oil after every two track days because it's sheared down to a 20w at 100*C. Those are, of course, generalizations best confirmed through testing, which is why I tend to review UOA's in applications/use cases similar to my own.

[zeroomega]

Originally Posted by KillerBMotorsport

Maybe? At 250° you've still got a buffer, but that drop in pressure is concerning. If you hit 260° it's time for a cool down lap and to consider an oil cooling solution. At 250° peak I would save my money and not add the extra weight and potential leak points.

Would be nice to see a bit more data here. Where were the temps measured from? Timing cover or sump? There's generally a 20° difference between the two, with the sump being colder. There could be various reasons for this, but in motorsports, taking temps at the sump is the standard.




Agreed. We're working on it




Careful what you wish for on this one!

The oil temperature reading comes from the car ECU. I think the sensor is somewhere after the oil filter. I don't have a hole on my oil pan to measure the temperature.

[zeroomega]

Originally Posted by BioRebel

I see a lot of people talking about going to 5w30 for track usage but I don't really get why. If you're trying to mitigate the oil being too thing at higher temps why increase the low end viscosity? Wouldn't 0w30/0w40 make more sense?


That being said, I agree that keeping the oil within operational temperatures is preferable to trying to guess what viscosity the engine likes at any given temperature. Looking @ the Jackson racing one since it keeps the conditioner, since I live in the NE I need that.

If you look at the oil from the same brand, 0w30 and 5w30 doesn't have the same HTHS spec or 100C (212F) viscosity, with 5w30 usually have higher HTHS rating. In NorCal tracks, usually there is no snow or freezing temperature so there is not much benefit for using 0w oil.

[KillerBMotorsport]

Originally Posted by zeroomega

The oil temperature reading comes from the car ECU. I think the sensor is somewhere after the oil filter. I don't have a hole on my oil pan to measure the temperature.

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.

[nissanfanatic]

Originally Posted by KillerBMotorsport

...it being purposely skewed.

Will try searching for this, but do you happen to have a link handy or a quick summary on "skewed" in this instance?