I've read glenn's article about the need for a Motorsports air/oil separator for track cars running race tires and generating high lateral g forces. I assumed this would not be relevant for me, as I still have my OEM Bridgestones. However, I had a LOT of oil smoke for a LONG TIME after my AX runs yesterday.

The circumstances: each AX session was 3 flying laps on the Redwood Region's (Zone 7) AX circuit at the Santa Rosa airport. This particular circuit is more like a short track than a conventional "cones in the parking lot" AX setup. Between each 3 lap run, I sat in the idling car awaiting my next run. After my 3rd run of 3 laps, I slowly motored over to the parking area and shut down the car. I probably ran the car for less than a minute after the final lap before I turned it off. Note that the final turn was a right-hand sweeper, with the lap ending in the middle of the turn.

When I restarted the car 5 minutes later, there was A LOT of white oil smoke. So much so that the other AX participants were alarmed. The smoke persisted for quite some time, and finally diminished as I drove away. Note : my oil level is exactly FULL.

Does anybody think this could be caused by the same problem glenn (and mooty) have experienced? What other explanation could there be? Should I let the car idle for 5 minutes after my last run? Do I need to do the air/oil separator mod? Maybe I should just drain some oil out to get to the middle of the range... Help!

Yes, there is some kind of issue with the oiling system on the Cayman when used in agressive driving. All sorts of claimed fixes from different oil separators to different oil scavanging pumps in the head to using an external oil catch system. While any one of those "might" fix the issue, the problem is that no one has really done a good engineering analysis of what is actually happening. Some claim the problem isn't serious and some claim that their engine failures are due in part to this problem so until Porsche either fixes the problem or releases the results of an engineering study on why it is happening and what the risks our I think the jury is still out and there may be some risk in running a Cayman hard at either autox or DE events.

In my experience you can almost always make it happen in the following combination:

Long straight followed by hard breaking, followed by sharp left hand turn followed by sharp right hand turn. If I do that and press it hard I will blow oil through the motor leaving a nice cloud behind me and then it will take time to slowly burn off through the motor.

I'm been told GT3 motors in Caymans don't do this.

__________________

To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts.
|
To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts.
|
To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts.
|
To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts.

K-Man S
To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts.

I'm sure this is the same problem we've seen before - was there a very tight left hand turn? Usually its tight left handers after very hard braking that make this happen - and it doesn't necessarily have to be the last turn you encounter before you turn the car off.

Idling the car for a few minutes after running seems to work for me. Last month at Thunderhill, (stock CS with Michelin sport cups) the only time in 4 days of very hard running that I had a problem was the one time I didn't let the car idle for a few minutes because I quickly shut down to jump into an instructor's car for the next session. The next time I started the car over an hour later for my next session caused a lot of oil smoke, which dissipated after a couple of minutes. I honestly don't think running the car lower on oil will fix this, and might make the motor more vulnerable to oil starvation in hard running.

brad

__________________
21-year PCA Member
PCA DE Instructor

Since you have the Mantis sump extension, it's clear that doesn't fix the problem. Have you noticed any correlation with oil level? It's hard to imagine this much oil getting past the rings, so the air/oil separator looks like a good suspect, as that would permit the oil to enter the cylinders through the intake manifold.

The end of the track I ran yesterday had a moderate straight, followed by hard braking to set up for a quick right/left combo around cones, then the RH sweeper to finish. Interestingly, I didn't notice anything after the 1st 2 runs when I sat idling.

Well, it was an AX circuit, so there had to be a hard left SOMEWHERE! LOL. I'll try your suggestion of idling for a bit next time, as the only time it happened was when I didn't idle after the run.

BTW - All Porsches do this occasionally. And, it is not always after running the car hard. I haven't seen anything concrete on why they do this, but it is most prevalent if you overfill the oil.

Every Porsche that I've owned has done this smoking on startup (1987 911, 1997 Turbo, 2000 Boxster S, 2004 996, 2006 Cayman S, 2006 Boxster S). It mostly happens at the track, regardless of whether or not I idled the car a while after a session. Sometimes it happens on the first startup in the morning.

Basically, they all do that!

Not filling the oil completely to the full mark seems to help.

I changed out my factory Plenum/Throttle body the other week for the Softronic version - and I was amazed by the amount of engine oil in the original assembly - oil is still dripping out on my workbench where the unit is currently residing.

It is quite beyond my comprehension that Porsche would make a system that encourages the ingestion of engine oil into the air intakes............ There must be a better way?

__________________
Cheers Karel
To view links or images in signatures your post count must be 5 or greater. You currently have 0 posts.


'Power is Nothing without Control..........'

I noticed the same thing when I did mine....

__________________
'07 Black/Black Cayman S
'07 White/Black Lexus IS 250
'08 White/Gray Jeep Compass

I too, have owned a lot of Porsches. This was not the usual smoke at startup. This was sustained, like oil was continuing to be pulled into the cylinders. The usual startup smoke is more like burning off oil that's gotten past the rings into the cylinders while the car was sitting.