fe1rx adds an Oil Sump Baffle

[fe1rx]

I had planned to go directly to an Accusump and forego an oil sump baffle altogether. Certainly on this forum baffles get no love, and any data showing their effectiveness is non-existent. A few things changed my mind:

1) I had a burning desire to inspect and replace my rod bearings before they conspired to ruin my day.
2) While the sump is off, adding a baffle is very little effort.
3) So too is installing a front main seal guard to protect against shredded belt ingestion.
4) I realized that any benefit gained with the baffle would still be beneficial with an Accusump.

A very thorough description of the rod bearing replacement procedure can be found here:

My rod bearing change proved relatively uneventful, with some wear visible on the old bearings, but nothing alarming.



Bottom End



I checked clearances before and after with Plastigauge.



Lower Bearings



Upper Bearings

I used King replacement bearings, which provide slightly more clearance (0.051 mm) than original (0.038 mm).

There are a few options when choosing a crank seal guard. I chose one by 034Motorsport. With the intercooler, radiator, the crank pulley removed, installation of the guard is easy.



Removing the sump requires supporting the engine from above and removal of the front subframe. This fully exposes the engine mounts for inspection, and in my case revealed that the RH engine mount had failed. I had expected it to be potentially heat damaged due to its proximity to the downpipes, but the damage appeared to be mechanical as opposed to heat-related.

When it comes to the baffle, there are a few choices. I chose the AAF baffle because it encloses a larger oil volume than the VAC baffle.





Both incorporate a keyhole shaped cutout to accommodate the support leg on the oil pickup tube. To my eye this is a serious deficiency in the design, as the keyhole slot will allow oil to pour out of the sump through the slot under left turns. Essentially, the slot negates the whole point of having a baffle. The following image shows the relative position of the pickup and baffle without the oil pan in place.




The above images show the baffle as built mocked up in place.

To address my concern, I welded a plate to block the keyhole.



Blocking the keyhole required removing the diagonal brace from the oil pickup tube. To recover some strength and stiffness, I installed an aluminum brace.







Of course the baffle needs to be welded into the oil pan. The pan came with no instructions for installation, so welding is up to you to figure out. The sump is ENAC AC-46000 alloy (BMW conveniently casts the alloy identification into it). This means that 4043 filler is a good choice for welding. The sump appears to be anodized, so it is necessary to abrade off the anodic layer before welding after first thoroughly cleaning and degreasing the sump. I preheated the sump to 100°C and welded with TIG. The baffle required a small amount of fitting to form a tight fit on the critical right hand side. The sump was no worse for the wear after welding, showing no signs of distortion.



The total oil volume below the baffle top plate is about 4 liters of which perhaps half is effectively constrained and available during cornering. Assuming an oil flow rate of 40 liters per minute (about 10 gpm), the engine will consume 2 liters in about 3 seconds. In other words, the baffle might provide only a few seconds of protection unless inflow into the sump replenishes the volume.

Those with an N55 have the (pricey) option of installing a secondary scavenge pump to solve their oiling woes:

https://grassrootsmotorsports.com/pr...ressure-issue/

As to how effective the baffle is, there isn’t a simple answer, but I do have a local track that allowed me to collect good data. I will follow up with a more detailed before/after comparison with some logged oil pressure data in my next post.

[tracer bullet]

Wow, as always. Informative and helpful, and it's appreciated you taking the item to record and share your work. As well as your dedication to doing it right and ingenuity to get there.

[Mach8-0]

Informative as always...eagerly awaiting the results of your testing as I'm going down this same rabbit hole in short order. Could you detail a bit closer how you affixed the brace to the oil pickup tube? I was considering rivets as my fears of loose hardware in the oil pan is nightmare fuel. Do you have any concerns about oil being able to return to the sump with the added blocking plate?

[hydra]

I know I'm a bit late to the party, but given the effort I'd much rather add an S55 oil pump + pan to the N54. You need to add a couple of PS pump mounting bosses to the S55 pan, and do some light mods to get the pump to mount to the block/windage tray. Shouldn't be a big deal for someone with your abilities.

[Cobra1956]

Went Moroso accumulator, ACL race and used the same baffle...FWIW

[ZHPizza]

FYI not sure if you saw this one little piece of data on the VAC baffle

https://www.1addicts.com/forums/show....php?t=1916461

Certainly not to your level of data collection, but better than "car ain't blowed up yet"

[KiwiClintE92]

Originally Posted by fe1rx

As to how effective the baffle is, there isn’t a simple answer, but I do have a local track that allowed me to collect good data. I will follow up with a more detailed before/after comparison with some logged oil pressure data in my next post.

Im really interested in the results you saw after fitting this modded baffle, did you get any oil pressure data after wards and what kinda lateral G's were you seeing? Im about to go down the same path.

[fe1rx]

Originally Posted by KiwiClintE92

Im really interested in the results you saw after fitting this modded baffle, did you get any oil pressure data after wards and what kinda lateral G's were you seeing? Im about to go down the same path.

I intended to write up my results, and started doing so, but basically found that I was splitting hairs so fine as to be indistinguishable from confirmation bias. I looked hard expecting to find a benefit. One big challenge is that the low oil pressure transients are very sensitive to oil level, so controlling for that in back to back testing of the with baffle and without baffle is difficult. Add to that the fact that the baffle does virtually nothing and it is easy to see what you want to see. The other real difficulty is finding a test track that reliably produces consistent transient responses. I have such a track close at hand. At the critical corner the transient trigger is very distinct and occurs at about 0.85 g (initiated by a dynamic transition from fast RH corner to long slow LH corner after with braking and unweighting at the transition). The depth of the transient and the time taken for the oil pressure to recover is alarming if the sump is not overfilled.



In short, I really couldn't come up with any conclusion except that the baffle does very little, if anything to improve transient oil pressure. I don't believe a baffle makes things worse, so I am not about to take it out. In my view:

1) overfilling 0.5 to 1.0 litres is essential regardless of configuration
2) an accumulator helps a bit but will be defeated if 1) isn't satisfied
3) a baffle provides no meaningful benefit

(I note you are a Kiwi. I was at the Rotary Reunion in Taupo a few years back )

[Onebunchmin]

What oil are you running with the new bearings? Did you use ARP bolts?

[fe1rx]

Originally Posted by Onebunchmin

What oil are you running with the new bearings? Did you use ARP bolts?

I used standard BMW bolts and I run Mobil 1 0W40.