Oil pressure issues and the Regs

#21

try a heavier oil. Our oil temps are blistering with the stock oil cooler. Try mobile one 15w50, great oil, can run very hot with no loss in oil pressure.

#22

mikeski38 wrote:

For thise of you runnig stock oil coolers with oil temp gauges, can you enlighten us to what temps you are running.

A good synthetic racing oil can endure 300F all day long.

Don

#23

donstevens wrote:

[quote]For thise of you runnig stock oil coolers with oil temp gauges, can you enlighten us to what temps you are running.
[/quote]

Mine has never gone over 220 ever, that is my highest recorded temp on synthetic oil in over 2 years. I have not raced in really really hot temps yet. It usually runs about 210 or so.

#24

No oil cooler, and temps go to 280 on hot days.The stock ES chassis did not have one and the IS engine transplant had been stripped of its cooler.

Engine (the Taxi) is still fine after 3 years of racing.

RP

#25

donstevens wrote:

[quote]mikeski38 wrote:

For thise of you runnig stock oil coolers with oil temp gauges, can you enlighten us to what temps you are running.

A good synthetic racing oil can endure 300F all day long.

Don[/quote]

I saw 220-230F at CMP (80-something ambient temp?). Mobil 1 15w50, stock cooler, filled to just below the “high” mark. My gauge pegs at 250F and I have never seen it approach that. Pressure consistently reads 50+ psi when in the race rpm range.

Steve D.

#26

mikeski38 wrote:

A heavier oil is not a panacea.

  1. A thicker oil doesn’t help you if the oil pump runs dry for a couple seconds.

  2. A thicker oil doesn’t help compensate for weaknesses in design. If the BMW design objective had been a race car engine, how would they have changed their oiling system design such that more oil flow went to places where the oil film might get thin under high stress conditions?

  3. Oil plays an important heat transfer role. Thicker oil doesn’t put more oil flow on local hot spots that are perhaps forming due to us running the motors harder then the design accounted for.

  4. Each bearing has a designed oil film, which is maintained in a dynamic environment controlled by a host of variables. Oil viscosity at 100deg C, is just one of those variables. Ihe BMW recommended Mobil1 5W-30 has a 100deg Visc of ~12.2 if I recall correctly. If we put in 50W with a 100deg Visc of 18, we’ve certainly changed the variables, but it would be a little hasty to assume that the engineer would thanks us for changing one of his design parameters by 50%.

High Visc oil results in high pressure readings because it’s so thick that it doesn’t want to go places. You want oil to go places. So you can’t just pour in 50W, watch your oil pressure go up, brush off your hands and exclaim “all fixed”. It’s more complicated then that.

I agree that high visc oil has some charms. But it’s not a cure-all.

Another tangent. We all talk about the danger long left handers. We say that because there is a history of seeing our oil pressure drop. What if brief oil pressure drops are routine in our motor, and we are just unaware of it? That could mean that bearing damage is routine, and that our motors only last until the cumulative bearing damaged becomes overwhelmeing. How long does the pressure need to drop before our sensor and gauge register a significant drop? How often are we looking at the oil pressure gauge in the middle of a turn? How many of us even have oil pressure gauges?

#27

I have an old bottom end with bearings that I replaced about a year ago. The #6 rod bearing finally gave up. The other bearings looked pretty good, but I replaced them all anyway. At the same time, put in a new oil pump. The short block has about 210,000 miles on it.

Also have a scraper, stock oil cooler, Redline 10/40 or 15/50. Temps don’t get above 230 or so.

Pressure maintains 30-60 at track speeds, no big drop in the left handers.

The motor was in a track-rat car for the two previous owners, and I bought the car that contains my race motor in 2003. So, I figure the motor has close to 10 seasons of heavy track DE/race duty, with a few thousand highway miles thrown in.

I don’t think it’s fair to say that these motors in more-or-less stock form can’t survive in track use. Sure, the foobar’d motors are very frustrating, but I don’t think that statistically we have a big problem with lower end longevity.

Now that I’ve posted this, I’m sure it will expire in a dramatic fashion at my next race, but this has been the experience so far.

#28

Steve D wrote:

[quote]donstevens wrote:

[quote]mikeski38 wrote:

For thise of you runnig stock oil coolers with oil temp gauges, can you enlighten us to what temps you are running.

A good synthetic racing oil can endure 300F all day long.

Don[/quote]

I saw 220-230F at CMP (80-something ambient temp?). Mobil 1 15w50, stock cooler, filled to just below the “high” mark. My gauge pegs at 250F and I have never seen it approach that. Pressure consistently reads 50+ psi when in the race rpm range.

Steve D.[/quote]

I saw the same as Steve D at CMP and have the same set up he does: stock oil cooler, Mobil 15w50. I do have a crank scraper and run about a half quart high. I see between 50-60 PSI oil pressure at speed and 25-30 upon start up/idle.

I noticed the oil pressure light flickering in sweeping left hand turns before the scraper went in but don’t see it anymore. I do see the oil pressure light flickering once I come off track and let the car idle. Gage reads around ~10-15 psi immediately after a session. I rev the motor and the pressure comes back. I normally see oil temps around 230-240 and water temp steady at 190. Water does climb once the car stops moving but the aux fan takes care of that.

I put the crank scraper in before the start of this season. Ever since I have owned the car (since 2006) it has been track duty only, probably 12 DE weekends and all 10 race weekends I have done, since 2007, I have seen exactly the same numbers summer or winter. Engine has 116K on it, original to the car, never rebuilt. The only thing done to it it was rocker arm replacement at the end of 2006 when I broke one (replaced them all). Car has never been dyno’d, not sure of power output but feels good.

#29

Ranger wrote:

[quote]A heavier oil is not a panacea.
snip
I agree that high visc oil has some charms. But it’s not a cure-all.
snip
How many of us even have oil pressure gauges?[/quote]

I absolutely love this kind of thread. I learn a lot by trying to figure stuff out. As you and I discussed this weekend, I have an OP gauge and low-pressure idiot light. I review a lot of video and have the camera positioned so I can see the idiot lights. I have never seen it even flicker on.

Here’s my counter-argument. None of it is based on actual knowledge, but instead from interwebs information cobbled together in a I-want-to-win-the-high-school-debate-competition style. :laugh:

Please poke holes, poke fun, generally ignore, etc.

The function of the oil is to create a layer for the bearings to float on. Higher viscosity oils have better film strength, so they fill in a larger layer better than low viscosity.

BMW engineers specified an oil that would work for typical street car temperatures at typical street car bearing clearances. Ours bearings are looser due to age and the operating temps are higher, requiring a higher viscosity oil.

The thicker oil isn’t covering up the symptoms, it is directly addressing them. Assuming the viscometer measurement is a good proxy for the thickness of the film the oil creates, a 30 weight oil (9.3 on the 100C viscometer) in a new 0.001" bearing clearance engine would be the same as 50 weight oil (16.3 @ 100C) with worn-out 0.0018" bearing clearance.

:S

Steve D.

#30

Steve D. you are absolutely right about clearances and oil. I choose to start with .002 clearances and modify the oiling system to provide plenty of pressure and volume.

I looked hard at the Accusump but did not like the restriction of the check valve in the main oil line. Does not work without the check valve.

The design of the oiling system is such that there is a 3/8" gallery running down the side of the motor. There is a plug at each end. It is designed to be fed by the oil plump and the pressure relief valve maintains line pressure. If you do not clean this and all gallerys with a brush after any kind of engine problem, you probably left crud inside the block to enhance your next problem.

There are low oil pressure sensors available for 20 or so $…each of you should have one with a light in your field of vision. It will probably be enough to scare superman. Chuck

#31

Steve D wrote:

[quote]The function of the oil is to create a layer for the bearings to float on. Higher viscosity oils have better film strength, so they fill in a larger layer better than low viscosity.

BMW engineers specified an oil that would work for typical street car temperatures at typical street car bearing clearances. Ours bearings are looser due to age and the operating temps are higher, requiring a higher viscosity oil.

The thicker oil isn’t covering up the symptoms, it is directly addressing them. Assuming the viscometer measurement is a good proxy for the thickness of the film the oil creates, a 30 weight oil (9.3 on the 100C viscometer) in a new 0.001" bearing clearance engine would be the same as 50 weight oil (16.3 @ 100C) with worn-out 0.0018" bearing clearance.

:S

Steve D.[/quote]

We’re saying pretty close to the same thing. I think that you are saying that high visc oil keeps worn bearings operating without additional wear, and I’m saying that high visc oil “helps” worn bearings operate without additional wear. In racing, that’s more consensus then usual.

But we’re not just talking about how to keep worn bearings alive longer. We’re talking about keeping bearings from becoming worn in the first place. The worn bearings that I just pulled out of my spare block saw 9 hard months of use where I was trying to get 6 track days/month.

I bet that Porsche motors don’t have to have their bearings replaced annually. Our bearing replacement rate is not normal. But we’re just being stoic and sucking it up.

Last summer I did a bunch of research on oil’s at www.BobIsTheOilGuy.com, a place where you can’t swing a trophy girl without hitting a tribiologist, or whatever oil engineers call themselves. One of the many things I learned is that oil is a lot more complicated then I thought and everything that I thought I knew about oil was wrong.

So now I’m really cautious about any sweeping absolutes about oil. And any time I hear anyone make any simple assertion about oil I’m immediately tempted to say “ok, but it might be more complicated then that”.

Steve, I really liked your gauges and idiot lights. I’m going to do something like that. I’m also going to do the accusump.

Can someone use a picture or diagram to show me where this oil galley and it’s ends are? I’m thinking that might be a good place to hook up the accusump. That way I don’t have to put a check valve in an oil line.

#32

I have nothing to add except to provide another data point (and hope that the engine doesn’t blow up on the next trackday).

Mr. Junky just finished 89th track day in 2 1/2 years. Always use Walmart 20W50 (used to be 5 qt for $7.60). I put all 5 quarts in during an oil change. Doesn’t seem to burn any oil.

Don’t have an oil pressure guage. My factory low oil warning light is always on (sender is broken). As far as I know, the oil pump is the original. No scrapers. I think the OEM oil cooler is still there.

260K+ on the engine. It was a track car when I bought it at 207K miles.

That’s all I can think of.

P.S. - Ranger, I am glad that you have moved on from the brake pads and brake bias. I mean that in a most sincere way.

#33

csrow wrote:

[quote]

P.S. - Ranger, I am glad that you have moved on from the brake pads and brake bias. I mean that in a most sincere way.[/quote]

Different season, different obsession.

#34

Scott and John, I am sorry to hear of your troubles. Dicking around with engine issues sure can take the fun out this hobby.

I think there is enough evidence in this thread alone support the hypothesis that there is no design flaw in our engines. There are literally hundreds of stories like Chi’s Mr. Junky where the car has been driven hard for thousands of track miles in sweltering ambient temperatures and the cars are still running.

The truth is, 100% of us (I believe) are driving cars that we bought used, most with 100K plus before we bought them, and we don’t really know the true health of the bottom end. Sadly, for Ranger, and much more sadly for John Eingold, they happened to get junkyard motors that already had worn bearings from some previous owners negligence. The guys who have recent rebuilds DO actually know what they have in the bottom end. The rest of us are just lucky.

I support the theory that 50 weight oil provides a better film thickness and thus prolongs the life of the bearings. Synthetic 50 weight oil, and more specifically synthetic racing oil, has even a little larger margin of error as it has superior HTHS specs to conventional oils. Racing oil is also better suited to continue to provide a film barrier in those momentary losses of oil pressure/flow. There is of course a point of no return where no matter which oil one has, it is going to be pushed out of the bearing if fresh oil doesn’t get refreshed PDQ.

Crank Scrapers and Accusumps are reasobnably priced insurance but offer little value if the root of the problem is bearings that were worn before one ever bought the car/engine.

What do we do? Installing crank scrapers, running accusumps, bigger coolers, top tier racing oils are all good things to do but if the bearings are already worn, none of these things are going to prevent a failure. How can we determine if our engines are already worn without tearing them down? Used Oil Analysis.

http://www.oaitesting.com I use this company because I get a discount through my Amsoil business.

http://www.blackstone-labs.com Is another altenative.

Both companies do essentially the same thing and who you use a is Coke or Pepsi type of decision. I will pass my discounts on to all who buy through my site though. Each kit costs about $20.00 and includes the lab fee, a nifty sample jar, and all the instructions you need.

Anything over 100 parts per million of most metals in the oil is a flag. Over 100 ppm of copper and lead is double red flag because that probably means that one or more bearings have worn through the outer steel shell and is now wearing the copper. While even with oil analysis it impossible to say exactly how worn the bearing may be. But once we see elevated levels of copper and lead, and worse a continuing trend of higher of higher wear metals, there is less margin for any oiling issue and it is really time for a rebuild.

Don

#35

Ranger wrote:

Excuse me.

B)

#36

natblack wrote:

[quote]Ranger wrote:

Excuse me.

B)[/quote]

Every time I leer in your direction John glares at me.

#37

Leer away. All I’m good for is glares. :frowning:

Bummer on the motor thing. I have a full engine and tranny in our garage, but it needs a full redo before it’s ready to replace my motor. I haven’t had one minute of issue with our motor (80K - but 75K of it’s life was spent as an automatic - which I think helps). Knocking on wood here.

#38

Don, bearings fail surprisingly often in our serius and they aren’t all junkyard bearings. I’m not saying that we understand all the causes, but I am saying that there are non-performance changes that we could make to the rules to make the situation better.

  1. Allow 360deg cut in main bearings.
  2. Allow coated bearings.
  3. Allow remote oil filters. This makes it easier to change filters, add sensors and an accusump. Make something easier and more folks will do it.

Someone tell me why those rule mods are a bad idea.

#39

Scott,

10-4.

“Someone tell me why those rule mods are a bad idea.”

I am not going to argue with you on this point.

Don

#40

Ranger wrote:

[quote]Don, bearings fail surprisingly often in our serius and they aren’t all junkyard bearings. I’m not saying that we understand all the causes, but I am saying that there are non-performance changes that we could make to the rules to make the situation better.

  1. Allow 360deg cut in main bearings.
  2. Allow coated bearings.
  3. Allow remote oil filters. This makes it easier to change filters, add sensors and an accusump. Make something easier and more folks will do it.

Someone tell me why those rule mods are a bad idea.[/quote]

Careful with the 360 degree cut thing. The reason why the top bearing is flat is to allow for the buildup of a thicker boundary layer of oil since the top bearing sees more load. If you remove surface area, you will decrease the thickness of the boundary layer and wear your bearings faster. and it is a performance advantage because now that bearing has a lower rotating resistance due to the smaller boundary layer. If BMW wanted a 360 ring there, there would be one. I would imagine that the BMW design engineers had more experiance with this sort of thing then we do, it would be a long shot to say we could redesign their motor and make it better. There is a something else going on here, not a design flaw in our motors.