Path to oil ingestion in the sump, on the track (m96/97)

Re: 996/986 997.1/987.1 engines - Does anyone know the path or entry point where oil is sucked up into the air oil separator - that some have issues with on the track or from simply over filling their engine oil? In other words, where is the hole or port(s) inside the sump that are connected to the intake side of the external air oil separator?

On bank 1 it's at the bottom tip of the AOS, which is directly on top of the bank 1 timing chain/rail. On bank 2 it's right above the intake cam sprocket. Both places have oil slung around pretty good when engine is running.

Hard right hand turns on the brakes. and hard left hand turns under acceleration is when the oil rushes toward the AOS ports. There is a high dollar Porsche Motorsport AOS that can help greatly with this also, but has to have a few modifications to fit some early cars. https://www.renntech.org/forums/appl...t.php?id=13340

Oh, I was surprised to hear the connection isn't made in the sump. ok. How would the hard cornering move oil into the timing chain area then?

Inertia and centrifugal (or centripetal ) force. The timing chains dip into the oil in the sump and act as conveyor belts flinging the oil around the crankcase. If the AOS is working properly, it maintains a slight vacuum enough to pick up the oil vapor but not strong enough to suck in the oil. I think more and longer oil exposure to these pick up ports will increase the likelihood of oil ingestion. ​​​​​​

Quotes source post: 14078203

Given the total amount of oil the oil pump can supply at any given engine speed, the valve train consumes a considerable amount of this oil so the amount of oil fed to the valve train hardware is considerable. As a result there is a lot of oil under the camshaft covers. This is courtesy of the oil that flows out around the lifter buckets and which is intended to splash lubricate the cam lobe/lifter bucket interfaces. The chains sling off considerable oil as they make the sharp turn around their sprockets located under the camshaft covers. The scavenge pumps -- one in each head under the camshaft cover -- can only do so much. Without air flow the oil that is under the camshaft covers won't flow to the scavenge pumps and under some operating condtions g-force works to force the oil to flow away from the scavenge pumps. The scavgenge pumps are located at the end of their respective head at opposite ends of the head. In the case of one head under acceleration g-forces tend to cause oil to flow backwards and this would be away from the scavenge pump. However, generally g-forces arising from acceleration are less than those generated by braking. Thus in the case of the other head with scavenge pump located at the opposite end under braking oil flows away from the scavenge pump. Since braking g-forces are most often higher and of a longer duration than those arising from acceleration and add g-forces arising from cornering to the equation the amount of oil that for a while escapes the scavenge pump is rather high. Then as the g-forces subside this oil then flows towards the scavenge pump but on its way there some of it gets whipped around by the cams and chains. This just adds to the considerable amount of oil vapor already present inside the crankcase. But the oil eventually reaches the scavenge pump which under these circumstances ingests more liquid oil than vapor and this can overwhelm the swirl pots which are there to help remove air from mainly oil vapor after it leaves the scavenge pumps. Because crankcase pressure can be high due to lack of low pressure in the intake under hard acceleration when low pressure does return there is a huge rush of air from the crankcase through the AOS and into the intake manifold. The AOS is overwhelmed by the amount of air and its very high oil vapor (or liquid droplet) content and the engine gets fed a rather large helping of oil. Then after the corner and upon the start of hard acceleration the oil that was delivered to the intake and which impacted the intake wall opposite the AOS hose connection to the intake is then pulled into the engine and burned and a big billowing cloud of oll smoke is the result. Under normal driving the amount of oil under the camshaft covers is pretty high (there is a YouTube video of the valve train of an overhead cam engine operating at high RPM and as RPMs climb the oil turns from liquid into a dense cloud of vapor whipped into vapor by the ferocious violent action of the whirling cams and the motion of the lifters and other valve hardware) and this oil vapor and oil vapor from the main and rod bearings, chains all add their share to the total oil vapor and as a result the crrankcase is full of oil vapor. Under track conditions an already bad situation is made much worse and the AOS and supporting hardware and plumbing are just not up to the task.

Thanks Macster