Oil pressure protection/cut track data

I recently had an oil pressure protection setup on my Link G4+ GTR Link PnP. Easy job and well worth it I'd say. The settings and method was very similar to the webinar.

Naturally the gp limit map and settings setup on the dyno need validating in the real world. So here's a data log from a track day at Silverstone. Sadly, my lappy ran out of batteries and i couldnt download the ecu logs before they got overwritten. Luckily I pull a good amount of the data into my data logger over can bus.

Spec: N1 oil pump, standard sump, Motul 15w50 300v slightly overfilled, 19row oil cooler.

You can see the pressure starts of nice and high with cold oil in red (out lap) it settles to a healthy 4.5 to 5bar until .... yikes sudden drop to 3bar at nearly 5000rpm in the middle of brooklands, high g (1.3G nearly) left hander.

The ecu is setup with a RPM vs Oil pressure RPM limit table and gives a hard ign/fuel rev limiter cut if the oil pressure falls below the minimum set in the table for a given RPM. And it did just that in this case. The logging is at 50hz iirc so the dip is only a fraction of a second long each time.

My question is: I wonder what would it have looked like without the protection? Are those big drops just a function of the ignition cut? Is what's really happening that my gp limit map is a little aggressive and just needs pulling back in a couple of cells, allowing a slightly lower pressure and avoiding the cut?

The chart is pressure vs rpm, each colour represents a single lap (sample laps taken from different parts of twenty minute sessions, to reflect the changing pressure as oil temps rise - peak oil temps around 110c on the factory gauge)

The graph would have looked exactly the same. Ignition cut won't affect oil pressure at any given RPM, it will just stop you piling on more RPM and potentially doing even more damage.

You need either -

Deeper sump

Baffled sump

Accusump

Dry sump

Err, you probably also need to pull you sump off and check your bearings. You SHOULD be OK as you are on decent oil, but any slight pickup may not be evident initially...until a conrod comes out to say hello.

Your oil temperature sounds a bit high, might be worth jumping up to a 25 row oil cooler. However a dry sump or proper baffled sump will lower oil temperature anyway.

What you need to remember is that it is the oil pressure that's activating the cut.

The fact that is is happening during a long corner to me would suggest strongly that you need to address your oil supply, the pump etc is fine but baffles would be a minimum, I have seen a few RB26's lost due to oil pressure loss during hard cornering, all addressed with baffles added. try that first and see how the data is after that, if you could add some extra capacity to the sump at the same time then that would be a bonus

Thanks for the responses guys. I should probably have said the car has completed a few thousand laps in this configuration prior to setting up the oil pressure protection, no glitter in the oil, no drop in pressure. I think regularly changed thick oil and a low rev limit makes a big difference. Obviously RBs are known for spinning bearings. I doubt any damage has been done here, the y axis is misleading the pressure is still 3 bar even in those dips.

The oil temps are a little higher recently, the cooler is between the rad and the IC and the IC is a bit clogged up with other peoples tyre rubber so cooling may not be all it once was - I have a new one to go on. I will go to a bigger oil cooler anyway I think and I'll turn off the protection for a session and review the data properly.

I did thousands of race laps in my AE86 without an oil problem. I then went that little faster (fixed suspension issue/improved driving) and a bit more power (fixed engine builder). Three blowups and £12K later I finally had the "one off" issue resolved.

Fixing it properly the first time would have saved me a fortune and not lost me a couple of championships.

True enough, hence the addition of the protection (one of the main reasons I went to the G4+, the old Nistune was doing it's job pretty well) when the oil pump starts to suck air things go pear shaped quickly.

The experience you shared is interesting; this does indeed correspond with a fractional increase in cornering Gs: maybe more aggressive driving or perhaps some effective (for once) suspension changes. Also it's possible I didn't overfill the oil quite as much as I normally would. The guys on SAU swear by overfilling but at least a litre for protecting the stock bottom end on track.

Reassuringly the drops weren't happening early on in the sessions when the oil temps were lower, this gives me the option of improving the cooling and throwing the check engine light when the oil gets hot to remind me to bring the car in for a cool down. If I can't get these pressure drops under control I'll look at pulling the engine for a bigger baffled sump. Dry sump isn't somewhere I'll go with this car purely from a cost point of view.

Would be interesting to see other people's oil pressure logs, especially of "untoward" events, does anyone have any to share?

One point about overfilling the sump...it can lead to higher oil temperatures. The spinny bits sloshing around in even more oil.

Can you produce a graph of pressure versus lap distance?

Adding a G trace would also be be handy.

Most loggers default view have the x axis distance, lap or sector.

I log a dozen channels and two cameras and I've spent a little time looking for the cleanest way to express this data, and then worked back to characterise the collection of parameters preceding the pressure drop.

In the end the two parameters that matter are oil pressure and rpm. To be meaningful in a single view anything else would need to be added on a z axis and my logger software doesnt offer that.

I don't want to get too much into the specifics of my car though, the question really was: what would you expect (based on experience rather than theory) a plot of rpm vs pressure to look like when the protection cuts the fuel and ignition. I want to be sure I'm not mixing up cause and effect.

I find logging oil pressure can be a mixed blessing - Often you're going to see something that you'd prefer not to know about. Of course once you know there's a problem, even if the engine is still perfectly healthy, it's natural to worry about it (probably rightly so), and try to find a fix. I had this exact situation on our 86. I added an oil pressure sensor quite early in its life and was surprised to see fairly regular oil surge occurring at our local track - In fact it would drop pressure 2-3 times per lap once the oil temp rose.

I went to considerable trouble building a baffled sump with a proper baffle box with trap doors and an extended pickup. I was understandably disappointed to find that it hadn't entirely resolved the issue and I was still getting some drop in pressure although now only at one point and not nearly as bad. My mind was put to rest when I looked at some data from a TR86 race car (local production race class using the Toyota 86 that use full slicks) and I found exactly the same trend despite their baffled sumps. Interestingly their workaround was to run a 15w50 oil so the base pressure is much higher, thus when the oil pressure drops, it doesn't drop as far. I didn't really like that for a street car as I already see 120+ psi regularly after a cold start.

Sooooo.... The point of this is that while no oil surge would be the ideal, if you're running a wet sump oil system this may very well be unrealistic. What your engine will cope with before damage occurs is going to depend on many aspects - engine power, oil type/grade, bearing clearance and engine rpm spring to mind. You're only going to be able to find out the hard/expensive way which I'm sure isn't that reassuring. Personally I wouldn't be overly worried about a momentary drop to 3.0 bar at 4500 rpm. My general guide is 10 psi per 1000 rpm minimum and essentially that's what you have - Any lower than this and I'd be getting concerned. That's not to say it isn't a bad idea to try and eliminate it but the fact you say you've been running the car like this with no trouble suggests the engine isn't adversely affected.

The problem may come when you modify the suspension further of fit better tires and your lateral g's increase slightly. That may be enough to push it over the edge and cause damage.

Thanks Andre, that all rings true. As you say the drops I am seeing aren't super low, infact still around the nissan factory manual guidelines for that rpm (although that spec assumes 7.5w30 oil). A fair amount of the surges were on trailing throttle too which helps, though there were one or two at WOT at corner exit.

I think I'll dial down the gp limit table a little, get it back out on track and then review the data. Just for belt and braces I have gone up from 19 row to 25 row oil cooler and I think I'll got to 10w60 oil too.

Just to follow up on this one. New bigger oil cooler (went from 19 to 25 row), fresh 15w50 as before, oil overfilled by maybe 1 litre.

Great fully dry 25deg day at Rockingham today. I left the GP limit table intact and there was no oil surge to be seen. Pressures looked more stable over time too.

We're you at the Nissan show today?

Good news on the improvement, do you think it's the extra capacity that's cured the dips? How were your oil temps?

I can't see the picture you've posted for some reason

Yeah, just on the track side, midnight purple R32 among the R35s. The track time was brilliant, barely saw another car all day, loads of grip.

Let me try that pic again. (Still not right, i'll have a go from my desktop later, struggling with my phone)

I think it was a combo of more oil and the bigger cooler. The oil temps never went above 110c even with 100c water temp. Longest was a 20min session. Hot day too and I was pounding the car.

https://youtu.be/jlJ4aQYsXcc

It did look like a great day, I never made it down unfortunately.

Oil Temps are well within what I'd expect for a car getting a pounding for extended periods, sounds like a problem solved and you can re-introduce the safety strategy without worry of false activations

I actually left the same gp limit protection table in place that I had at Silverstone in June, I decided to leave it switched on as an early warning in case my changes didn't work. This time I managed to bring a fully charged windows tablet with PCLink on it with me so I could tweak things if necessary. Came in handy in the end as there was enough grip to setup my high boost setting on the link, didn't quite nail it so I may post a separate thread on that.

btw I think I fixed the image above now but basically when hot I now have 450kpa from 4000rpm where I was seeing more like 414kpa at 4000 and not safely getting 450kpa until 5000rpm before, and of course not seeing the big drops.

HI Alex,

Just found this thread and notice you said you'd be interested to see other peoples logs.

Mine are from an R33 GTR at Donnington Park (RB26, GT2860-5 running .8 bar, Toyo T1R tyres, Accusump)

Not the greatest idea but due to work being hectic and family life, by the time I had finished wiring in my Link G4 Xtreme, I had just one evening to 'throw' a map together before I was due at Donnington Park..I couldn't cancel because as a birthday surprise for my son I was letting him drive my GTR around the track.

I was running Silkolene (Now Fuschs Titan Race Pro S) Pro S 5w40 as recommended, I will now be running 10w50 Titan Race Pro S.

I fitted an Accusump when I first got my GTR back in 2010 and plumbed it in using the standard 2 bar pressure valve as I mainly at the time wanted it as a pre oiler, and an emergency warning if my oil pump failed, my idle oil pressure sits just over 2 bar so this meant that the Accusump wouldn't keep opening at idle. I had no idea the oil was surging as I was running an Apexi Power FC with no oil logging and the gauge obviously didn't react quick enough to show the surging.

When I fitted the G4 I did setup an oil pressure vs RPM limit but in my haste to get it mapped, I hadn't noticed it had a 2 second delay before activating, this explains why it never kicked in on the track...scarily, I did have one brief moment where coming down the straight at the very end of the day I hit a limiter but was only at around 5500rpm so it wasn't a normal rev limiter and because at the time I only had the G4 not the G4+, the datalog had filled and stopped recording...I called it a day when that happened as I couldn't explain what had caused it.

I have since setup my new G4+ to control the Accusump using a 3D table and set the Oil vs RPM limiter to activate after 0.2 seconds...this will hopefully give the Accusump a chance to correct the oil issue before bringing in a safety limiter.

I did notice at the end of the day that my rear turbo return hose had split slightly and had been weeping, this had caused the oil level to drop to bang on the max mark, whereas I usually have it to slightly higher than max, this may have been the cause of the surging as looking at the data, I very much doubt my engine would have survided the amount of track days I have done over the last 7 years with how low the oil pressure was dropping (note it only ever dropped a fraction below 2 bar so the Accusump I assume did help a little at the time)

Also, I had a pillar pod with an Innovate oil pressure and temperature gauge, although initially watching it like a hawk, I never witnessed any drop in my oil pressure so assumed all was good.

Anyway...I have attached the very scary looking oil pressure vs RPM XY plot.

Edward.

Yikes! that is properly scary. Is that on a standard oil pump?

Yes, the engine is all standard internals, sump, pump etc.

If I do a pull from low revs in say 3rd gear, I have a nice linear climb in oil pressure until I hit around 4,500rpm and then sometimes I see the oil pressure starting to slightly drop/fluctuate so I suspect I have the known issue of oil getting trapped in the head and not returning to the sump.

I seen a few occasions where under heavy braking and cornering the oil pressure drops dramatically as well, as this was all on the track I suspect the same issue, most of the oil is in the head so when going from high revs and jumping on the brakes, the oil pickup is no longer submerged and causes the drop.

I will work around it for now with the Accusump/overfill/thicker oil and monitor it very closely but ultimately I am going to need to pull the engine to deal with putting a breather in the sump to allow the oil to travel back to the sump more freely, and a better baffle setup i.e Tomei trap door system.

It is a shame really as I run Federal RSR's on my track R32 and love them but I don't dare stick them on the 33 as I think that extra grip would be the death of the engine.

Edward.

Hi Andre, I have a GT86 too with the same problem, I tried adding a baffle plate (from TMG) and using an uprated oil pump in order to increase the oil flow and so the pressure. I still have drops until 0.9-1bar over 4000rpm (should have at least 2-3 bar). I would like to use a 10w60 oil but the engine supplier advertise me against it due to bearing clearances, so I'm using 0W20 as they advertised (IAG).

Do you have the logs from tr86 in order to have a reference?

Considering the duration of the surge is 0.4-0.8s and (correct me if wrong) the pressure sensor location (as OEM) is before the oil filter it is possible that after the filter you would probably measure a drop too but not so deep?

Have you ever tried to measure in a different location?

NOTE: lateral force are around 1.5G (slicks), log freq is 50Hz with AIM sensor and datalogger