Overflow oil tank is puffing smoke

[JohnJL]

I am trying to diagnose and deal with a problem thats always been there but has gotten noticably worse recently. The motor has a season on it, and wasnt stessed hard, there no reason it should be acting differently so I wonder if I just didnt notice it so bad before or if anything has changed.

The motor is a 3.2l supercharged running ~12psi or .9 bar.

I have a 2+ litre overflow tank plumbed off the oil filler neck. It has a filter on the top, and it drains to the 4-5-6 upper valve cover. It does not fill up with oil, but it does puff smoke out the filter with each cylinder firing. I took the filter off the overflow tank vent and see it clearly puff. If I block that filter hole and open the oil filler neck, it puffs out there with each cylinder firing.

The smoke is prolofic. I need to do some better sealing of the firewall to the cabin, so I get lots of smoke in the cabin now, particularly shortly after I come off full throttle and get back into it after a corner. Even when the cabin is fully sealed, I cant have that smoke coming off the back. The filter on the overflow tank tends to cool/collect the oil vapor and it drips down in the engine compartment and on the headers. Very stinky and smokey.

Firstly, I am not sure why this is happening and if it indicates a problem. Right now I have the normal oil line coming off the oil filler neck to the engine case. I also have that same filler neck venting to the overflow tank, which is the one smoking like crazy. Should I be plumbing this differently?

I scanned a couple of alternatives, not sure if these would help. Both are variations on feeding that smoking bent back into the intake. The obvious downside being I would now be feeding my engine intake with oil vapor which cant be great.

Anyone help with diagnosis of whats happening, why, and what I should do?

If I do plumb it into the intake, seems it would need to feed in before the throttle body, right? Option 2 below would seem to bleed an unlimited leak after the throttle body, which would essentially be a major intake leak.

Thanks!

[Ronnie's.930]

One thing that what you describe can be a sign of (which you won't want to hear/read) is excessive blowby into the crankcase (as in broken rings). Of course, you would have to do a leakdown test to make sure.

Isn't .9 bar much too high boost pressure for a 3.2's static compression ratio? That would explanin the broken rings (provided that is your problem).

[M5guy]

A holed piston in a Porsche makes a lot of smoke under the circumstances you describe. No odd noises and no sudden loss of power.

[JohnJL]

The pistons are fairly new 8:1 JE coated pistons with dual plugs and knock control (though I've never had pinging register except when tapping the block with drift to check if its working). Its possible I have a broken ring as I havent checked leakdown recently.

[Ronnie's.930]

If the oil smoke/vapor is coming out of the crankcase in the manner you describe, then you have a blowby problem. Have you tried running the engine with the crankcase vent hose removed from the oil tank to check for smoke from there (isolate the source of the smoke)?