Tooth count on the S54 and S52 crank shaft sprocket that drives the oil pump

[aeronaut]

aeronaut,
you may be right about the hydraulic lifters not needing more oil than solid lifters. I don't know that they do.

My whole premise was to increase pressure/flow to the S52 head on the basis that lifter tick is a symptom of a lack of oil in the head when puling lateral Gs on track. That would explain the scoring on the camshaft journals. Scoring that is pretty common when I looked at used S52 cams. I'm looking for increased flow regardless of the way to achieve it, based on my assumption that the head is starved. I could be wrong.

I will update at the end of next racing season. Hopefully with good news.

I think you're absolutely right.

FYI, I also think scoring on the cam journals is caused by something chunky and hard in the oil. If you look, I think you'll find a lot of the time the score is located in line with the oil feed hole in the journal. So some particulate gets pushed into the journal through the oil feed, and embeds itself. That's a theory anyway.

[pbonsalb]

Most S52 cams are scored. Even with less than 200k miles and no racing.

[Franky goes]

pbonslab
If that is so, my objective has now be downgraded to reduce (Instead of eliminate) scoring of the camshaft...
...You don't always get what you want...

[NeilM]

On this topic of buying used, is the Euro S50 oil pan essentially the same in this application?

Yes, as long as it's from the S50B32; this is the pan I have. The S50B30 didn't have the dual pickup oil pump.

Both the Euro dual pickup pump and pan have detail differences compared to the S54 parts, but are physically interchangeable. Here's what mine looked like after bead-blasting:

DSC00848-sm2.jpg

DSC00850-Sm.jpg

Neil,

Prior to the VAC modified pump, and with the S50 Euro pump/pickup setup, you say you were seeing 40 psi oil pressure at around 3,500 rpm. What were you seeing at idle?

Not sure I remember accurately, but with cold oil over 10 psi, and with hot oil the oil pressure light was flickering (not uncommon). I don't worry much about idle pressure, since the engine is under no load. But it was irritating. Bumping the idle speed by 100 rpm would certainly take care of it.

FYI, I have read that both the S52 and S54 oil pressures are limited to 58psi. Wondering if anyone can confirm?

I believe it's 4 bar nominal max for both, so 59 psi.

Neil

[NeilM]

I'm not sure I buy into the belief that the hydraulic lifters on the S50/52 require higher oil volume (or pressure) under normal conditions. The way I understand how they work, there's very very little flow into/out of those lifters once they are pumped up. And even if they are 'empty', they pump up very slowly.

aeronaut,
you may be right about the hydraulic lifters not needing more oil than solid lifters. I don't know that they do.

My whole premise was to increase pressure/flow to the S52 head on the basis that lifter tick is a symptom of a lack of oil in the head when puling lateral Gs on track. That would explain the scoring on the camshaft journals. Scoring that is pretty common when I looked at used S52 cams. I'm looking for increased flow regardless of the way to achieve it, based on my assumption that the head is starved. I could be wrong.

The hydraulic lifters definitely do require more oil than solid lifters. This is born out both by theory and practice.

Here is a very interesting page about BMW hydraulic lifters:
https://www.enginebuildermag.com/200...ppet-problems/

First, when the lifters pump up, they do not retain their internal oil pressure forever. Their ball check valves are not perfectly effective, particularly when they're old. (There are You-Tube videos on how to clean and recondition them.) Second, if the oil pump pickup gets exposed during cornering it'll inhale air, and eventually some of that air will quickly make its way into the lifters, causing the well known lifter clatter we'd all like to get rid of. I've personally seen oil pressure drop well into the teens in a particular corner (T8 at Putnam) with the stock S50/52 pump.

Not only do the lifters require oil flow to keep them pumped up, even once that happens, their pressurized oil feed via the lifter tray oil galleries will still constantly flow out around the lifters and into the tray bores in which the lifters move. There are no oil seals there, just the lifter OD to bore ID clearance, and there are 24 of those bores to drain away oil pressure.

Then, after using the same oil pump guts for years in various different engines, BMW downsized the pump, starting with the S50B32 engine that uses solid, non-hydraulic lifters that otherwise resemble hydraulic lifters, but which function as passive spacers. The lower capacity pump was then carried over to the S54, which has no lifters at all, instead using finger cam followers.

We can only guess, but a reasonable supposition is that the downsized oil pump was intended to reduce parasitic loads on the engine, increasing net power output and decreasing fuel consumption. All manufacturers have been doing that with driven accessories, which is why we now have electric power steering, variable displacement A/C compressors, and so on. My Golf R daily even has a dual displacement engine oil pump that's electronically switched between high and low outputs, depending on demand.

But when you take the lower output pump and install it on an engine with higher oil demand, the result is reduced pressure, since the pump is now being asked to supply a whole new mechanical sub-system. Oil pressure and flow are inversely related:



When you add another branch to the oil distribution tree, thus increasing oil flow demand, oil pressure drops unless the pump has surplus capacity. That's exactly what we see when a stock S54 pump is dropped into an S50/52 engine. And when the higher capacity modded S54 pump is substituted, the pressure drop goes away.

I don't claim any particular virtue — much less good financial sense! — for having done this, but I'm likely one of a pretty small group of people who've tried stock S52, stock S54 and modified S54 pumps on the same car with no other changes. (And yeah, I've become bizarrely proficient at changing out oil pumps.)

The results, positive and otherwise, speak for themselves.

Neil

PS: Which is not to say that the dual pickup pan/pump is the only way to go. It's an elegant solution, and has the considerable virtue of using stock, albeit tweaked, parts. It's also entirely internal to the engine, which is where I like my oil to be. But it's not cheap, although careful shopping can make it much more affordable than using all new parts.

But people like the Accusump, which seemingly does its job and is relatively economical. You do have to mount it somewhere, and run oil lines, install control valves, wiring, etc. For similar cost you'd be a chump not to address the root cause rather than applying a bandaid — but the cost isn't similar.

[aeronaut]

Good stuff! I like learning how all this works (or doesn't).
I had settled on the accusump, but was concerned about where I'd mount, and I really didn't want to run oil lines into the cabin. That, with the fact accusump makes a big deal about mounting the accusump solidly, had me wondering.

Then, another member offered a used S54 setup for a reasonable price. And yea, now everything will be managed in the oil pan. I was on the fence with the VAC oil pump mod. The FI guys seem to have some alternative fixes for this, but requires detailed knowledge and machining. If it were Dec and not Feb, I'd probably investigate and save a few hundred dollars. So I'll likely be sending VAC my pump and a chunk of cash, all to buy "I'll never worry about this again".

The only question is which will take longer; me making a decision on springs and getting the head back from the machine shop, or FEDEX and VAC. I've got 3.5 weeks to the first event. Gonna be tight.

[NeilM]

Then, another member offered a used S54 setup for a reasonable price.

The magic words! ;-)

VAC turned my pump around in a week or less. YMMV.

Neil

PS: Make sure they know it's for an S50 application, otherwise you'll get an S54 sprocket.