Addressing N5x oiling and spun rod bearings (Accusump installed)

[doodlebro]

So, I tried the infrared thermometer method for checking oil flow/return lines, and realized it's not even necessary. There's a roughly 50 degree (F) gradient from the return to flow lines for the cooler, so it's easy to tell which is which when the cooler has been used. For the X3 at least, the return/flow lines are labeled correctly in RealOEM, so I'll have this new return line fabbed with a fitting and check valve, and then have my shop figure out a better intake before I have them install the Accusump, hopefully in the engine bay near where bnks did. Maybe I don't need my AC compressor...

Also, for anyone wondering, the N55 xDrive pan holds 6 QTs to the tippy top. I imagine non-xDrive is the same because the xDrive pan has a bit of extra room/a cubby on one side to make up for the axle cutout. I still haven't decided which electric pressure switch I am going with, but it helps to know that the Accusump dumping probably won't cause issues at any engine speed. Just have to make sure it's filling properly before shutoff so I get the pre-oiling benefits.

 

[F87Source]

So, I tried the infrared thermometer method for checking oil flow/return lines, and realized it's not even necessary. There's a roughly 50 degree (F) gradient from the return to flow lines for the cooler, so it's easy to tell which is which when the cooler has been used. For the X3 at least, the return/flow lines are labeled correctly in RealOEM, so I'll have this new return line fabbed with a fitting and check valve, and then have my shop figure out a better intake before I have them install the Accusump, hopefully in the engine bay near where bnks did. Maybe I don't need my AC compressor...

Also, for anyone wondering, the N55 xDrive pan holds 6 QTs to the tippy top. I imagine non-xDrive is the same because the xDrive pan has a bit of extra room/a cubby on one side to make up for the axle cutout. I still haven't decided which electric pressure switch I am going with, but it helps to know that the Accusump dumping probably won't cause issues at any engine speed. Just have to make sure it's filling properly before shutoff so I get the pre-oiling benefits.

nice!

Btw: it's return on the right and outlet on the left correct?

 

[doodlebro]

nice!

Btw: it's return on the right and outlet on the left correct?

I think so for your car, but for X/5/6 series, it is the other way: flow to cooler on the right, and return on the left when looking at the engine from the front. I would just trust whatever realOEM says for your car as far as outlet/return and go from there. Or do what I did and get the oil hot enough and find the cooler feeling pipe.

 

[F87Source]

I think so for your car, but for X/5/6 series, it is the other way: flow to cooler on the right, and return on the left when looking at the engine from the front. I would just trust whatever realOEM says for your car as far as outlet/return and go from there. Or do what I did and get the oil hot enough and find the cooler feeling pipe.

lol the oil temp gets up to 95ºC so that is going to be fun feeling pipes.

 

[doodlebro]

lol the oil temp gets up to 95ºC so that is going to be fun feeling pipes.

I understand it sounds bad haha. As long as the engine bay is not heatsoaked and has been getting airflow, but the oil temperature has been above 240F for a bit, those pipes should be well below 180F and not super dangerous to touch. Last night when I checked at the top of the road I was driving mine were ~160F and ~110F. It helps if you have a cool mountain to drive up.

 

[F87Source]

I understand it sounds bad haha. As long as the engine bay is not heatsoaked and has been getting airflow, but the oil temperature has been above 240F for a bit, those pipes should be well below 180F and not super dangerous to touch. Last night when I checked at the top of the road I was driving mine were ~160F and ~110F. It helps if you have a cool mountain to drive up.

Yeah no lol, im going to buy a new infrared thermometer.

 

[Asbjorn]

So we found that it wasn't feasible to enlarge the oil sump after all. So we just added an oil dip stick and replaced the rod bearings. Since the oil pressure problem is mainly there when trail braking in to left hand hairpins, we also decided to cut the baffle wall. Acceleration shouldt be a problem anyhow, and now it is ever so slightly more similar to the S55 setup.

This part was removed

View attachment 37575

The electronic oil pump will continue to return oil from the front of the pan to the pickup under breaking.

Here are the old rod bearings. Put 150.000km on these. No idea where the metal in the oil filter came from. We have changed filter twice since then and haven't seen any new metal in there...

View attachment 37576

Btw it was really cool that we could use the oil pressure warning signal to crank the engine after installing the new rod bearings. After 6-7 cranks with coils disconnected, the oil pressure warning stopped, and we knew oil pressure was sufficient. It also seems oil pressure is ever so slightly higher now after the rod bearing and oil change. Btw the gaps where around 0.04mm, just used oem type.

Alright, the small baffle re-design made no difference, and the oil pressure still drops when trail-braking into tight left hand turns. Below is a video of a lap from last sunday. As I go through turn 8 around the 0:52 mark you can hear the siren (despite driving with the top down). The siren sounds because the oil pressure drops below 50-60psi, which is the idle oil pressure when the oil is 70C /160F cold.

Anyhow, I like the siren much better than the previous oil pressure gauge, because now I can hear when I can and cannot push the accelerator pedal.

 

[F87Source]

Alright, the small baffle re-design made no difference, and the oil pressure still drops when trail-braking into tight left hand turns. Below is a video of a lap from last sunday. As I go through turn 8 around the 0:52 mark you can hear the siren (despite driving with the top down). The siren sounds because the oil pressure drops below 50-60psi, which is the idle oil pressure when the oil is 70C /160F cold.

Anyhow, I like the siren much better than the previous oil pressure gauge, because now I can hear when I can and cannot push the accelerator pedal.

Holy crap lol your siren sounds like the ALP alerts (laser jammer). That would have me bugging since I would constantly think I was getting hit with laser if I heard that alert.

 

[Asbjorn]

Holy crap lol your siren sounds like the ALP alerts (laser jammer). That would have me bugging since I would constantly think I was getting hit with laser if I heard that alert.

Did another hot-lap, this time with the roof up. You can hear the siren better in this video. It even chirps a bit at the end of the braking zones. This, even the oil pump returning the oil from the front of the pan to the rear while braking was active.

 

[sancho78rus]

Hi!

I've been watching for this thread for some time.
Why are you trying to solve the low oil pressure problem without cooling upgrade?
The colder the oil, the greater the pressure.
I think you need second coolant radiator and air ducts to oil and coolant radiators.
Look at my temperature on logs

datazap.me | sancho78rus | stage 1+

datazap.me

datazap.me | sancho78rus | Igora1

datazap.me

 

[F87Source]

Hi!

I've been watching for this thread for some time.
Why are you trying to solve the low oil pressure problem without cooling upgrade?
The colder the oil, the greater the pressure.
I think you need second coolant radiator and air ducts to oil and coolant radiators.
Look at my temperature on logs

datazap.me | sancho78rus | stage 1+

datazap.me

datazap.me | sancho78rus | Igora1

datazap.me

Because it's not a cooling issue, it's because upon cornering oil moves from the pick up causing oil starvation. More cooling doesn't address this.


On the m2, m3, and m4 bmw added extra baffles and a secondary pump to address this.

 

[sancho78rus]

At different temperatures the oil has different viscosity.
I believe it matters a lot.

 

[F87Source]

At different temperatures the oil has different viscosity.
I believe it matters a lot.

Not when the G forces are pushing it away from the pick up. Imagine a tilted cup with a straw in the middle. It doesn't matter if the cup is filled with honey or water if the fluid is not touching the straw it cannot be sucked up and therefore oil starvation and low oil pressure.


oil viscosity doesn't vary much after a certain temperature, so it wouldn't matter too much unless you are going past the oils temperature threshold.

Cooling would already be upgraded to its limit on a track car like with @Asbjorn's setup so there is nothing left you can do there.

 

[sancho78rus]

Just imagined cup with a straw.
I think it does matter.

 

[F87Source]

Just imagined cup with a straw.
I think it does matter.

Well you need to familiarize yourself with oil starvation then. Because oil can be as thick as tar but if the G forces prevent the oil from reaching the pick up then it doesn't matter since the pick up will be sucking air.

Look at this chart: https://www.elephantracing.com/tech-topics/oil-temperature-and-engine-life/

After oil hits warm up temperatures viscosity barely changes as temps increase. If the oil temps were at racing conditions do you realize how much cooling you would have to have to get any sort of meaningful viscosity changes to get any sort of oil pressure changes?

Also this is not the oil pressure you want, a more viscous fluid would be harder to pump through the engine providing less protection. For track use you want the cooling to be sufficient so the oil does not shear from high temps, not to make it so cold it gets more viscous.

 

[Asbjorn]

Hi!

I've been watching for this thread for some time.
Why are you trying to solve the low oil pressure problem without cooling upgrade?
The colder the oil, the greater the pressure.
I think you need second coolant radiator and air ducts to oil and coolant radiators.
Look at my temperature on logs

datazap.me | sancho78rus | stage 1+

datazap.me

datazap.me | sancho78rus | Igora1

datazap.me

It seems the logs you shared have different hardware and tuning. Either your FMIC is heat-soaking (too small), or your turbos are too small, because your peak IATs are much higher than mine, even your ambient temperatures are much lower. Your IAT curves remind me a bit of when I was running the VRSF 7in FMIC. If you track alot, I recommend upgrading.

It seems ambient temperature was around 20C / 70F in both track logs? In that case I am not super surprised you are able to keep coolant temps below 100C / 212F as they where. Looking at the logs, your power output per lap is probably smaller than mine, and with the 6MT radiator and a second coolant radiator, your effective radiator area isn't much smaller than mine.

Here's my cooler setup, just for reference.





I think it is fair to say that upgrading oil coolers or adding an oil pump has not "solved" anything on my car. But back to the other topic.

Here's my temperature situation over one lap:

datazap.me | Asbjoern | BQ v46L - RON98 - WI - GIC track log

datazap.me

Key data from the log:
Ambient: 33C / 92F, humid
Start coolant: 203F 95C
Peak coolant: 230F 110C
Start engine oil: 248F 120C
Peak engine oil: 266F 130C
Min IAT: 104F 40C
Peak IAT: 120F 49C (had ice cubes in the WI tank)
Transmission: 199-212F 93-100C

Below you can also see a comparison of the coolant temp development over one hot-lap in different ambient conditions:
RED: 16psi map 33C / 92F ambient, roof up
BLACK: 18psi map 26C / 79F ambient, roof down, heater on

Interestingly, the shape of the graphs look about same, only one is 7C lower on average, which coincidentally is exactly how much cooler it was outside. This just goes to confirm that ambient conditions play a huge role in how effective the cooling system is.

 

[F87Source]

It seems the logs you shared have different hardware and tuning. Either your FMIC is heat-soaking (too small), or your turbos are too small, because your peak IATs are much higher than mine, even your ambient temperatures are much lower. Your IAT curves remind me a bit of when I was running the VRSF 7in FMIC. If you track alot, I recommend upgrading.

It seems ambient temperature was around 20C / 70F in both track logs? In that case I am not super surprised you are able to keep coolant temps below 100C / 212F as they where. Looking at the logs, your power output per lap is probably smaller than mine, and with the 6MT radiator and a second coolant radiator, your effective radiator area isn't much smaller than mine.

Here's my cooler setup, just for reference.

View attachment 41269

View attachment 41271

I think it is fair to say that upgrading oil coolers or adding an oil pump has not "solved" anything on my car. But back to the other topic.

Here's my temperature situation over one lap:

datazap.me | Asbjoern | BQ v46L - RON98 - WI - GIC track log

datazap.me

Key data from the log:
Ambient: 33C / 92F, humid
Start coolant: 203F 95C
Peak coolant: 230F 110C
Start engine oil: 248F 120C
Peak engine oil: 266F 130C
Min IAT: 104F 40C
Peak IAT: 120F 49C (had ice cubes in the WI tank)
Transmission: 199-212F 93-100C

Below you can also see a comparison of the coolant temp development over one hot-lap in different ambient conditions:
RED: 16psi map 33C / 92F ambient, roof up
BLACK: 18psi map 26C / 79F ambient, roof down, heater on

View attachment 41272

Interestingly, the shape of the graphs look about same, only one is 7C lower on average, which coincidentally is exactly how much cooler it was outside. This just goes to confirm that ambient conditions play a huge role in how effective the cooling system is.

if you really want to drop temps you can look at c02 sprayers. Not sure if racing events allow for a tank of compressed gas in the trunk.

 

[sancho78rus]

Did not see your config.
In this case, adding cooling is not about you.

It seems the logs you shared have different hardware and tuning. Either your FMIC is heat-soaking (too small), or your turbos are too small, because your peak IATs are much higher than mine, even your ambient temperatures are much lower. Your IAT curves remind me a bit of when I was running the VRSF 7in FMIC. If you track alot, I recommend upgrading.
It seems ambient temperature was around 20C / 70F in both track logs? In that case I am not super surprised you are able to keep coolant temps below 100C / 212F as they where. Looking at the logs, your power output per lap is probably smaller than mine, and with the 6MT radiator and a second coolant radiator, your effective radiator area isn't much smaller than mine.

I have stock engine with stock turbos now. Not stock FMIC, similar to VRSF 7in. Stage 1+ MHD tune.
Temp reached 110C after one lap on track before we upgraded cooling, added air ducts and large second coolant radiator. Now coolant temperature is under 100C.

How do you get oil pressure logs?

 

[Asbjorn]

Did not see your config.
In this case, adding cooling is not about you.


I have stock engine with stock turbos now. Not stock FMIC, similar to VRSF 7in. Stage 1+ MHD tune.
Temp reached 110C after one lap on track before we upgraded cooling, added air ducts and large second coolant radiator. Now coolant temperature is under 100C.

How do you get oil pressure logs?

Great call on the large second coolant radiator. Highly support that. Get a better FMIC though. You want something twice as big as what you have.

When you watch the video I posted you can hear a siren in the hairpin of turn 7. The siren sounds because I have an adjustable oil pressure switch which is set to open below 50psi oil pressure (or whatever the oil pressure is, when the oil temperature is around 70C iirc). When it opens, it connects power to the siren. And thats all it does.

Before installing the oil pressure switch I had an oil pressure sensor and an analogue gauge in my cabin. I would record videos of the gauge while driving around on track and study it afterwards. Then I tried different ways of making my oil sump semi-dry including modifying the baffle two or three times. In the end I did not find anything that would cure the problem, and now I just live with it as is. When I hear the siren, I don't go WOT. Simple as that. And if a track is left handed, then I just don't compete there anymore. Right handed tracks are much easier on the oil pressure.

The N55 can log oil pressure via MHD, and the testing we have done at the same track showed that the issue is very similar. The drops happens in the same corners and under braking, just a bit earlier.

 

[AndyW]

Thx to this thread I ordered my Accusump system...it's bigger in person...lol.