Give me a break, Mark.

At this point, you'd have to be as dumb as a rock not to know that you are the exception, not the rule, regarding track engines.

Go run your engine at 6,000 rpms at WOT, under full load, for 90 seconds and let me know how it works out, for you. Hell, take it out, bring it down, and I'll pay for the dyno session....as long as I get to hold the throttle open!

You have to clean the oil and the pieces out of the dyno cell, afterwards....

I "saw" zero problems with Andy's engine until we held it at 5,500 rpms, for over 60 seconds. That didn't mean there was not oil stacking up in the heads, before that rpm, it just meant that it took that long for the drains to fill and the level to get high enough, in the heads, to be ejected. Over two quarts, in each head, prior to reaching the "oil ejection" level.

We now know, through testing, that the drains are "overwhelmed" and backed up by 3,800 rpms. The crankcase no longer can "exchange" air, with the heads.

You can debate this until hell freezes over, but until you have run an engine on an actual engine dyno and observed what happens with the oil...you simply don't have enough data to debate intelligently.

 

No, I did not. I actually increased the crankcase breathing, by adding an additional vent into the crankcase. The pump moves oil (and air mixed with the oil, of course) back into the crankcase. That should increase the crankcase pressure. However, now that the drains from the heads are not completely covered with oil, the crankcase can "exchange air" through those big passages, also.

 

And as I mentioned before, not every engine has this problem.

This is a problem that is easy to diagnose.
Take your breather hoses off your engine, put the car in neutral, and rev the heck out of it.
See what comes out the breather hoses.
If it's just vapor, you should be fine.
If you get oil foam, then you know that oil is ending up in your intake,
which is NOT a good thing....

 

I have heard of return system like this on the LS motors. Typically, they route the crank case and valve cover breather tubes to a catch can that is vented. On the bottom of the catch can, where it is normally drained, they install a tube to directly drain into the oil pan. They essentially create a loop for the oil to flow external to the engine block. They block off the ports on the intake manifold. Those using this claim it works. Is there a reason why this would not work on the 928? Also, did you try to use an electric oil pump so it can be switched?
Thanks.

 

I so want Kibort take up this challenge.
Come on Kibort put up or shut up, every one of these engines has this problem , I have had them all on the dyno , under high load revs you will be surprised how much oil can mess up the floor under the car .
Destructive beside the bloody fire hazard .

 

That is basically how the SharkVent from 928 Specialists works, I have one and it does the job well. BUT, it does not address the issue of oil packing into the heads like Greg's kit does. Greg's kit dry sumps the heads and returns the oil into the pan so the crankcase can vent properly without oil getting into the intake, and keeps oil over the pickup in the pan. Really a great solution to a well known 32v 928 engine problem.

 

No, although I thought about it...I decided that the electric pump would be too complex and the mechanical pump would be easier.

After seeing the incredible amount of oil that the belt driven pump sucks up, I now also question if an electric can keep up (in the higher rpms), so I'm happy that I selected the "mechanical" pump, for my application. The electric pumps are also a "gear" design, which I decided need lots of oil to keep them lubricated. The "roots" design pump that I used does better with "smaller" amounts of oil...which is what it will get, at the lower rpms.

John Gill (Australia) is going to try the electric pump and switch it from his stand alone fuel injection system. With most of the modern fuel injection systems, you can switch things on and off at specific rpms. For his "road racing" application, I think it will work. Even if the pump gets overwhelmed at the high rpms, hopefully it will "catch up", when he shifts.

One thing that is obvious, now that I've seen the problem. Anything will work a ton better than doing nothing.

 

Now, this is something, you are right, i have no experience. the longest Ive been full throttle is 17 seconds at road america. BUT, what does WOT have to do with anything? wouldnt just the RPM hurt the situation. if 5500rpm is the threashold, and even at 3800rpm is a problem, then again, I ask why I have seen no issues. remember, at the race track, ill run for 50mins at never an RPM level less than 4000rpm. certainly 30mins at between 4500 to 6500rpm with no breaks , in recent races!

Im wondering, how the oil cant return through those 4 big return holes! I dont know, and have only seen the "window" on the valve cover test.

Anyway, you certainly have me scared. maybe its the the constant rpm. who knows.

But, until i decide to do a sacrafice dyno run, ill continue to race as I have for over 10 years. and the scientists here can try and understand what is really going on in my engine, devine intervention or something logical.

 

WOT you have some amount of flow going past the rings, through the crankcase, up the drains, and out the vents to the intake. Bound to make the situation a bit worse.

Why not control how much oil goes into the heads?

 

"Why not control how much oil goes into the heads?"

This has already been thought of, considered, discussed, reviewed and rejected as being a high risk sub-optimal option that Porsche (with their higher pressure 944 valves) must already have rejected. All discussed somewhere on this thread, somewhere between the 1st post and this post!!

 

One thing you do not see in Project 928 is multi-axis dynos. You see static dynos that ran tests hundreds or even thousands of hours long.

Recently, Porsche posted a youtube video of one of their latest engines being run on a multi-axis dyno simulation of the Ring. It turns out this was subcontracted out. Cosworth (not the company performing the latest tests) mentions having a multi-axis dyno for testing in one of its past papers on measuring oil aeration. I will go out on a limb here and suggest that Cosworth Engineering was used by Porsche in the late 1980s or early 1990s to study aeration problems in the 928 engine on their multi-axis dyno which I am assuming existed even then. I believe Porsche passed along suspension setup tips and driving style suggestions to Max Moritz.

These suggestions allowed the wetsump engine to survive almost a full season of racing without 2/6 bearing failure. I think Mark just has an innate ability or feel for the car that allows him to duplicate this. If Mark ran his engines at sustained high rpms as I am sure Moritz did, then he too might have a failed motor every season.

The attitude of the car affects where the oil goes in the crankcase and the degree to which air is entrained in the oil. It is simple physics. Mark should be complemented that he has had the patience to continue saying this in the face of heavy criticism, from myself included, over many years.

I am very sure if another driver was allowed to push his cars into another attitude then engine failure would soon result. Discoveries are often made by closely examining and accepting anomalous data instead of treating is as noise or excluded outliers.

Great job, Mark.

 

S4s and GTSs have a 'low oil level' sensor and dash display. I would expect this to be conservatively positioned by Porsche so as to activate well before the oil level goes so low as to expose the oil pick up. Are there any reports of this system triggering before - even momentarily before - any of the well documented engine (oiling) failures? At high revs I accept that even if the system were to trigger it may be too late to reduce revs quickly enough to let sufficient oil to travel naturally from cam covers to sump, but still wondering if anyone who has 'lost' an engine has noticed this before the event. If not I wonder why not.

 

I have here in my neighbourhood two 30 km autobahn tracks I use frequently with my S 3 and I can drive there max. speed.
I have a 86.5 5 speed with the 1:2,73 gearbox and at top speed the engine revs ~6000 rpm.
If I run the car there very fast I have exorbitant high oil consumption.
My weekly trip is ca. 450 km so you can burn 2 l oil in 1000 km.On second grade roads you need half the oil.
This car had recently a broken timing belt pulley bolt so we opened the engine and the rings are worn but the interesting thing is huge carbon build up on pistons and valves.
Maybe related to flowed heads?The engine has 230000 km and valve shaft seals maybe are also worn.

 

Great point. if so much oil was missing, enough to starve the pan, the sensor would go on, and on the other side of that, you would think under acceleration when its close, it would go on, because the oil float is in the front of the pan.


Thanks. I dont know. I try and think a little bit about what is going on in the motor to gex max power when I need it and not kill it when I dont. is that the reason? I dont know enough about what exactly is going on. But, what I will say is that the "whipping" theories, and such, all make me think. the crank counterweights are pretty flush with the bottom of the short bock. I dont think the oil gets very close to the crank elements. in decel, it all bunches up forward, in acceleration it drifts to the rear and side to side, you coudl bunching up the oil to the sides of the crank. does anyone know what the oil level actuallly loooks like at 9 quarts. how much is suspended in the heads reduces this number.
again, im drivng the snot out of the motor. watch any video, as you can see the entire 30min, the rpm NEVER gets below 4000rpm.

To your point, i dont think I would ever let anyone else drive my car, but then again, Scot has had no issues either and he beats on the car pretty hard too, on the same tracks.

This does sound risky, but again, i have no clue what is good ,and what isnt as far as amount of oil to be present in the heads.

I forgot about this key point. I guess the WOT point, is pressurization of the crankcase, and thus it vents to the intake for relieve. if there is any oil in the lines, it will be pushed out if the flow is great enough, plus if that flow was great enough, wouldnt the car run like crap, as that is pure exhaust gas. wouldnt that show up on the dyno AFR reads??? forget WOT, but off throttle decel, the vacumm is very high and then the engine itself, will pull anything it can based on a pressure drop of the intake vs the crankcase through the little breather tubes. sure, if the heads are packed with oil, it will such pure oil, but if that was the case, i would think during racing, more oil would be burned and some smoke would be present in the tail pipe.
see my rear view cam to see only a puff of smoke occasinoallly during a alll out GTGP race at lagujna Seca. listen to the revs. Im not babying the engine either.

 

http://www.youtube.com/watch?v=KrrH5H5kWCw

go to 10:35 on the video and watch for a lap. see any smoke?? hear the revs?? these are 1:36-7 laps.