bldn10

I have an '06 Cayman S w/ 3.8L X51 997 engine installed by FarnbacherLoles w/ 25000 miles on it.

At Barber last weekend I blew a huge cloud of smoke at the end of the straight after the 180 degree left-hand hairpin. Been there many times and this has never happened before. No oil leaking, no noises, no CEL, checked w/ PIWIS and NO codes or other evidence of trouble. Drove around a bit and it cleared up. When back out to check it and after a few laps it did the same thing twice in the same place and hen I parked it. Drove 250 miles home w/ no smoke.

Any ideas? AOS? Other oiling issues like scavenge pump?

utkinpol

yeah, most typical suspect would be AOS.
keep an eye on your oil level now and inspect exhaust tips to make sure driver side is not getting noticeably more soot than other side.

bldn10

I'd like for it to be the AOS but let me add that some nice guys at the track put a vacuum tester on the oil filler and it was w/i normal range. Apparently if the AOS diaphram is split there will be higher than normal vacuum - they say sometimes you can hardy get the cap off.

I'm not sure that the tips (Cayman, remember) relate to one side or the other.

BTW Paul, my car came your part of the country.

Macster

IIRC that setup results in a build up of oil under the right side camshaft cover. g-forces force the oil away from the scavenge pump and the oil really piles up.

Then out of the corner and on the gas the oil rushes past the whirling cams which whips the oil to a froth and on to the scavenge pump which adds to this.

Momentarily the engine crankcase has a huge load of oil vapor which overwhelms the AOS (which is in some cases is already
overwhelmed to begin with) and a big cloud of smoke is the result.

USMC_DS1

You my want to consider a deep oil pan with baffles. There are several out there. I have not tracked my car yet but I went with the FVD setup to prep it... https://rennlist.com/forums/997-foru...l#post10245275

bldn10

"You my want to consider a deep oil pan with baffles."

For the occasional DE driver like I think the X51 pan should be sufficient. I've not had this happen before so something has changed - the AOS, an oil pump, pan baffles, something.

alexb76

or you are faster...

Macster

Bingo.

bldn10

"or you are faster... "

Yea, that must be it! No, actually the contrary - I was out on street tires just to test my brakes, having just replaced the master cylinder, put on braided lines, and fresh SRF. I was going relatively slow. and when I went back out later in the day to check it out I intentionally slowed down, but it still did it.

Also, if it only happens in high-G LH turns, doesn't that weigh against an AOS failure?

chris.hanle

I assume the oil itself is fairly fresh and not the issue, and the ambient temps are not unusual. Keep us posted.

bldn10

New Mobil 1 and K&N w/ about 300 miles on it. It was in the mid 80s. This was after only 3-4 laps.

USMC_DS1

Was the engine "x51" from the factory? or was an "x51" kit added after the fact? Difference being that I don't recall the kit coming with an x51 pan + baffle. The baffles are key to address this type of symptom... it may be worth it to remove your oil pan to check if it has the x51 baffles.

Luxter

And I bet, your oil temps were high too easily bringing your oil into 30 grade range.
Low NOACK (and 50 grade) oil would at least help the cause.
ACEA A3/B4 require NOACK equal or less than 13. Redline, as an example only not a suggestion, offer NOACK = 6.
Indeed, AOS can be tested with accurate vacuum gauge.
Around 4" - 6" water column is about OK, 8" and above indicates AOS going South...
I agree with Macster's scenario.

bldn10

Crate X51 straight from Porsche.

cibergypsy

The X51 motor, either crate from the factory or having the kit retrofitted, doesn't have a different oil pan in the 997 version, only for the 996 version of the X51 kit. The oil pans for both the regular engine versus either the X51 from the factory or the kit retrofitted are the same.