Addressing N5x oiling and spun rod bearings (Accusump installed)

[JohnDaviz]

After seeing this I am starting to wonder if this a problem at all?

So over pages and pages ppl are working on improving pressure in certain situations, BMW introduced the dual oil pump on the M2 for track driving and you ask if this may be is not an issue
The pressure is dropping heavily on higher RPM so that the bearings MAY run dry for short periods of time because the oil film might tear for a split second. Oil starvation is an issue over time not a sudden killer (mostly). Though in those situations the load on the bearings is actually not so high a reduced pressure might be okay. But probably not below idle pressure. A bit of common sense.

BMW designed the cars we are speaking here about for street use and less than 0.6g lateral forces.

If you do not think that this is an issue you can rely to that FB discussion recently with just overfilling a liter and you are good to go .

What your "test" shows is exactly what i told you on FB that the level of oil (and overfilling) on our engines is not helping really much in critical situations.

If it wasn´t an issue at all... again.. why did the M2 then get the dual oil pump solution?

 

[Bnks334]

So over pages and pages ppl are working on improving pressure in certain situations, BMW introduced the dual oil pump on the M2 for track driving and you ask if this may be is not an issue
The pressure is dropping heavily on higher RPM so that the bearings MAY run dry for short periods of time because the oil film might tear for a split second. Oil starvation is an issue over time not a sudden killer (mostly). Though in those situations the load on the bearings is actually not so high a reduced pressure might be okay. But probably not below idle pressure. A bit of common sense.

BMW designed the cars we are speaking here about for street use and less than 0.6g lateral forces.

If you do not think that this is an issue you can rely to that FB discussion recently with just overfilling a liter and you are good to go .

What your "test" shows is exactly what i told you on FB that the level of oil (and overfilling) on our engines is not helping really much in critical situations.

If it wasn´t an issue at all... again.. why did the M2 then get the dual oil pump solution?

I think he was talking specifically about the braking logging showing pressure drops. There is no way you could say that this is not an issue altogether lol. I don't think we need to recap all the reasons why.

 

[CNM135i]

I think he was talking specifically about the braking logging showing pressure drops. There is no way you could say that this is not an issue altogether lol. I don't think we need to recap all the reasons why.

Correct. The straight line braking with minimal engine load. I have no doubt that long term high lateral G's are harmful. From @Asbjorn Aim log we can see that my car has no problem with a 0.8G corner for 2-3 seconds.
I have no intention of running anything stickier than the Cup2 so just trying to gauge what is really needed then. If 25psi during hard braking is "normal" then we should not worry about short term dips.

 

[JohnDaviz]

I think he was talking specifically about the braking logging showing pressure drops. There is no way you could say that this is not an issue altogether lol. I don't think we need to recap all the reasons why.

Yeah i know. But now i see that he was testing at 1500 RPM before braking

 

[Bnks334]

Yeah i know. But now i see that he was testing at 1500 RPM before braking

yeah I didn't see that either. He is basically stalling the car. I can definitely see how rapid deceleration at <3k rpm can cause the oil pump to struggle to stabilize oil pressure for a split second and be a factor in what CNM is showing. It's still concerning to see the oil pressure can dip so low in these situations though. Being below idle oil pressure is probably never a good thing.

I generally don't look at much data below 3k rpms though. I know from logging oil pressure on a coasting decel from 6k rpm down to 2k rpm that we should be over 60psi at 3k rpm. It does happens every once in a while in really tight autoross turns purely because it's slower to downshift and the upshift again than it is to just leave in in 2nd, but, on a roadcourse I don't see any reason to have to drop below 3k rpm. You'll be lugging the engine which is just as damaging.

I have logs showing the car at <30 psi at over 3k rpms. That is where I brought in the braking situation. I wasn't talking about 620rpm lol. Heck I have my idle at 950rpm.

 

[Asbjorn]

Yeah i know. But now i see that he was testing at 1500 RPM before braking

The problem is there at higher rpms as well.

So what we have seen so far is that oil pressure dips below idle pressure on n55 without baffle during hard braking on track. The two n54s who provided data were both baffled and did not report this problem.

The second main theme is oil pressure dropping below idle when trail braking into 1G left handers. This has been reported for both n55 w/o baffle and n54 w/baffle.

With the new pump system on mine, it is still dropping in this last scenario, but we have yet to see it go below idle pressure.

oh and finally bkns has also reported dips during right hand turns, which neither I or the m135i has experienced. I have however had fuel starvation in right hand turns lol...

 

[JohnDaviz]

The problem is there at higher rpms as well.

I know Why are you not installing an Accusump? Moutune in Australia recently said in an interview that a Baffle with Accusump is the best way to go besides dry sump.
That is my route also but i was wondering if i could skip the baffle and go just with the accusump and if it has to be the 3 quarts version....

Another thing is.. I am wondering if anybody ever asked BMW directly and officially for the lower oil pressure limit during tracking on n54 and early n55 engines.

Looking at your data i would already be pretty happy and just adding a small accusump maybe.

 

[Asbjorn]

I know Why are you not installing an Accusump? Moutune in Australia recently said in an interview that a Baffle with Accusump is the best way to go besides dry sump.
That is my route also but i was wondering if i could skip the baffle and go just with the accusump and if it has to be the 3 quarts version....

Another thing is.. I am wondering if anybody ever asked BMW directly and officially for the lower oil pressure limit during tracking on n54 and early n55 engines.

Looking at your data i would already be pretty happy and just adding a small accusump maybe.

Well, I was hoping to solve the problem at the root though an M-inspired semi-dry oil sump. And I agree... after seeing the M135i data, I definitely feel happier. But I will do some more testing with stickier tires to see if the pressure ever drops below 50psi, and then consider next steps from there. I might still prefer deepening the oil sump + pickup over the accusump route as I already went down this path.

 

[Asbjorn]

Rate my oil filter... around 7000 miles on it... changed oil once without changing filter around the 2k mark. Put around five slick-tire track sessions on it, as well as 10 or so sessions running normal semi-slicks.

I don't know how "normal"-use street car oil filters looks like after regular oil change intervals, because one has to cut it open to check, and I never cared enough to do that previously.

 

[Bnks334]

Rate my oil filter... around 7000 miles on it... changed oil once without changing filter around the 2k mark. Put around five slick-tire track sessions on it, as well as 10 or so sessions running normal semi-slicks.

View attachment 34281

I don't know how a "normal"-use street car oil filters looks like after regular oil change intervals, because you have to cut it open to check, and I never cared to enough to do that before.

That is a lot of metal. When I spun bearings at the track I didn't really even have much metal in my filter lol (they are the first 3 pics in google drive on page 1).

On a regular oil change I'll find maybe 2-3 flakes throughout the whole filter. Nothing like that.

 

[Asbjorn]

That is a lot of metal. When I spun bearings at the track I didn't really even have much metal in my filter lol (they are the first 3 pics in google drive on page 1).

On a regular oil change I'll find maybe 2-3 flakes throughout the whole filter. Nothing like that.

I found your google drive. To me it looks very similar actually? But you say it is nothing like this on normal oil changes?

 

[Bnks334]

I found your google drive. To me it looks very similar actually? But you say it is nothing like this on normal oil changes?

View attachment 34282

They shiny stuff there is oil. I just expected a lot more metal when I opened up the filter considering 3 out of 6 bearings were spun and the other 3 were scored lol

I've cut open quite a few of my oil filters and no I've never seen metal in them like these pics. Both before and after the engine rebuild. Never see more then a few flakes.

Have you ever checked your cam ledges?

 

[Asbjorn]

They shiny stuff there is oil. I just expected a lot more metal when I opened up the filter considering 3 out of 6 bearings were spun and the other 3 were scored lol

I've cut open quite a few of my oil filters and no I've never seen metal in them like these pics. Both before and after the engine rebuild. Never see more then a few flakes.

Have you ever checked your cam ledges?

Good info, thanks. The metal might be turbo bearing related then, I have had an issue there recently. Will get a quote to replace those rod bearings anyway.

My cam ledges are pretty worn. I got vanos codes a year ago due to this. The kind that would only show up when the oil got hot on track. Since replacing the vanos solenoids didnt help, we replaced the cam metal rectangurings with the N55 teflon types. No vanos codes since then. I assume only the teflon is wearing now, and that I will get a vanos code when they need replacing.

 

[Asbjorn]

btw @Bnks334 how confident are you in this statement you made in post #1?

"our cars can easily pump 3qts of oil out of the pan in a 2 second long sweeping turn or a 2 second long threshold braking situation like at the end of a drag run."

If the volume is this big, ie 24gpm, then a 3gpm gear pump might never be able to make the sump "semi-dry".

 

[JohnDaviz]

Rate my oil filter... around 7000 miles on it... changed oil once without changing filter around the 2k mark. Put around five slick-tire track sessions on it, as well as 10 or so sessions running normal semi-slicks.

View attachment 34281

I don't know how a "normal"-use street car oil filters looks like after regular oil change intervals, because you have to cut it open to check, and I never cared to enough to do that before.

Holy Cow. I would not drive that car anymore. I had less metal debris with a spun rod bearing. And my bearing was really done.

Don´t worry. The rest of the bearing was safe in the block

 

[Bnks334]

btw @Bnks334 how confident are you in this statement you made in post #1?

"our cars can easily pump 3qts of oil out of the pan in a 2 second long sweeping turn or a 2 second long threshold braking situation like at the end of a drag run."

If the volume is this big, ie 24gpm, then a 3gpm gear pump might never be able to make the sump "semi-dry".

Reality is that it is an RPM dependent statement. I think automotive oil pumps generally flow between 4-30gpm depending on RPM. So yeah... 3qts in 2 seconds would be around 22.5GPM. It's just a guesstimate. Shouldn't have phrased it so definitively, but, it's highly plausible.

Pumping oil from the front of the pan to the rear is meant to help keep the pickup wet. It has to work to some degree. Like you just presented, it's likely the sump would still be operating at a net loss of oil capacity if not also being heavily supplemented by oil returning to the pan naturally from gravity.

The rate of flow wasn't something I even thought about tbh. Maybe that's why BMW uses a second oil pump. The scavanger pump at 3gpm would be basically idle flow?

 

[Asbjorn]

Reality is that it is an RPM dependent statement. I think automotive oil pumps generally flow between 4-30gpm depending on RPM. So yeah... 3qts in 2 seconds would be around 22.5GPM. It's just a guesstimate. Shouldn't have phrased it so definitively, but, it's highly plausible.

Pumping oil from the front of the pan to the rear is meant to help keep the pickup wet. It has to work to some degree. Like you just presented, it's likely the sump would still be operating at a net loss of oil capacity if not also being heavily supplemented by oil returning to the pan naturally from gravity.

The rate of flow wasn't something I even thought about tbh. Maybe that's why BMW uses a second oil pump. The scavanger pump at 3gpm would be basically idle flow?

Yeah so I guess it is fair to assume the BMW secondary pump out-flows the electric oil pump I use in order for their system to work. It would also be rpm dependent which is what you need.

And as far as I can see I can't buy an electric oil pump that flows more than 1-2gpm, so it will only ever just delay the underlying problem, even if the working principle is correct.

What I am left with then is a slightly confused / unreliable oil temperature gauge. As the electric pump and associated cooler only runs during braking, it now means the oil temperature fluctuates up to 5 degrees C:

datazap.me | Asbjoern | three laps ZIC wet time attack

datazap.me

At least this is still an improvement over the 13C drops I saw when the oil was delivered outside the baffle right next to the oil temp sensor:

datazap.me | Asbjoern | BQ v31 - WI - temperature logging

datazap.me

Anyway, I have decided to replace my rod bearings next month, and before any new track activities. My car has 140.000km on the clock, and that metal in the oil filter is concerning. So this means I have to remove the oil pan once more. So this got me thinking...

What is interesting about both my car and my friends M135i is that no oil pressure problems have been discovered during right hand turns. This makes me want investigate how far the pickup is offset to the left, and then prepare to deepen the sump and pick up by the same amount. At least from a theoretical stand point, this should solve the problem for both left and right hand turns, right?

And I might as well try and install a dip stick at the same time. Because if I increase the volume of the sump, the idrive oil level computation would be wrong anyway.

 

[Asbjorn]

So just to clarify with mspaint... what I think might be the problem, is that the pick up is offset like this:

Where red is the oil level during 1G right hand turns, and green is the oil level on 1G left hand turns.

I don't know for sure, but that's my theory from behind the laptop.

 

[Mterkait]

VAC just released their baffle.. maybe a bit too late? idk
https://store.vacmotorsports.com/vac-motorsports-oil-pan-baffle-bmw-n55-p4854.aspx

 

[F87Source]

VAC just released their baffle.. maybe a bit too late? idk
https://store.vacmotorsports.com/vac-motorsports-oil-pan-baffle-bmw-n55-p4854.aspx


View attachment 34634
View attachment 34635

It also says it's m2 compatible too. Hmm I wonder if this is a typo or if it will fit and actually improve on the 1.2G rating from factory. I doubt it will fit when looking at how the m2 sump is already baffled vs. a stock n55.