GPA951s

So on the Dyno my car was smoking on boost, ALL the intake/intercooler tubes are super clean no sign of oil. The plugs look perfect and the car made good HP.. However, when I got up on boost it smoked blue smoke like crazy... I took off the Turbonectics turbo and put on a freshly rebuilt factory kkk turbo. Took it for a shakedown on the street and no smoke.
Took it to the track, During my third stint I came into a Righthander uphill (toe of the boot WGI) and got a oil Wiff.... looked in the mirror and saw a cloud of mosquito killing blue smoke... pulled the car in.. The motor is tight, Fresh everything, pistons, rings, head, The only thing I can think of is that I Vented the AOS to a catch can and on boost I have oil in the return tube (motor mount to pan) backing up into the Ex turbine. Does anyone have any Experience with this scenario? I think the way that return line is plumbed into the pan the crankcase needs the venturi effect of being vented in front of the turbo. Thanks Guys..

Tom M'Guinn

You might pull off the drain hose and make sure it's clean and not gunked up, along with the mount. If you're not already, I'd vent the crank to atmosphere to see if that helps (pull the oil cap and cover with pantyhose or the like). A slight vacuum in the crankcase helps drain the turbo, but as long as there isn't a lot of pressure in the crank it shouldn't prevent two different turbos from draining. I get some pressure in my crankcase under heavy boost and have no smoke. Not to be a wet blanket, but I'd probably want to check the rings with a leak down test too....

cruise98

Sounds to me like the oil seal on the turbine shaft is leaking into the exhaust.

Tom M'Guinn

On two different turbo?

GPA951s

Yea that was my thinking.. Two different turbos? That are both pretty much new? Sounds like a systematic problem... When I switched the Turbos I did blow out the motor mount and the line to the pan... BTW Even after all of this, the Oil itself is so clear that it is hard to read on the dipstick. Tom, I DO have the AOS vented to atmosphere... THAT I think is my issue. The AOS Needs that little bit of vacuum to create negative pressure in the crankcase under boost Hence the factory has that AOS vent tube in front of the intake to the turbo. Im Boosting to about 14psi BTW.
Im going to have the Turbos checked out and re-do my AOS venting back to a more Factory type setup. I will do a leakdown just out of curiosity.

Noahs944

I'm sorry I can't help but it sounds like you are on the right track to finding the root cause of your problem. My research came up with 8 lbs of vacuum is ideal for a daily driver. The electric vacuum pumps can be adjusted to whatever you desire with the right electric switches. You just "t" into the brake booster hose is my understanding.

Off topic: May I ask you if your engine is 2.5litre & do you have any ideal how much torque and hp the 2.5 engine has at 14psi? I heard the factory head gasket is "approved" for 17 psi, is this true?

Tom M'Guinn

GPA951s

Its originally a 2.5 block but its at 4.100 now.. 14 psi boost made 305 ftlbs and 271 hp at the rear wheels. I have a Cometic gasket on it.. on the street for a couple of hits every once in a while Im sure a bit more boost would be fine but this is a track car and lives above 4500 all day long Any more boost for a track car will cost allot more money There is no longevity for these engines above that on the track, it can be done but with allot more money....And BTW I Torqued the head to 85 ft lbs with Raceware studs...

Dan Martinic

ealoken

Valvesteam seals?

Paulyy

It does help using metrics with a metric car, it does confuse people.
Could be valve stem seals. or stems

He means 104mm bore. or 4.1 inch bore.

bw993

When you vented the AOS to the catch can, was the catch can open to atmosphere or connected back to the J-boot or MAF?

Dan Martinic

Thanks. I was getting very interested in the 4 litre motor though

Paulyy

https://rennlist.com/forums/944-turb...a-thing-3.html

Scroll though that. It's been done, hopefully we get to see it run this October. It may or may not be running at the moment as it's all secretive at this point in time. I have very high hopes.

Dan Martinic