79 turbo falls off boost

[fredmeister]

I just got back from my first DE at Watkins Glen in my 79 930 turbo....first DE in the turbo as I have driven many times before in my 911SC.
I had a question on several items that bothered me with the car that occurred at the track.
1) The car went thru several quarts of oil at the track yet it does not burn a drop in over 800 miles street driving. Every time I started the car at the beginning of a session it would smoke heavily from the exhaust for about 3 minutes before it would clear up. It would puff at every upshift on the track as well.
My question was is it possible that the oil was getting pulled thru the tank breather into the inlet side of the compressor causing the loss of oil and heavy smoking? I was told to keep the oil level slightly below the minimum mark on the stick to prevent this from happeneing, but I was skeptical to run the oil level below the min mark......OPINIONS on this?
2) I noticed after 3-4 laps once the car was hot, it would hesitate or stumble on acceleration at around 4500-5000rpm. It would then pick up and run again if I eased off a little, but it almost felt like a miss or momentary shut down. What could this be?
3) At the same time as all this was going on I noticed that the oil gage pressure would bounce occasionally, is it possible that I was experiencing the oil foaming issues that plagued early 911SC before they changed the venturi pick-up on the oil pump, DOES THE 79 930 TURBO HAVE THIS ISSUE? IS THERE AN UPGRADE KIT TO SOLVE THIS?

[dheinz]

Bump

Fred, sorry I don't have an answer, but this reply will get this topic back on the first page.
It was a great time at the Glen and a pleasure to meet your family.
Keep in touch.

[fredmeister]

Yeah Ed, it was fun as always........sorry we did not stick around after my family arrived but we wanted to spend time together as I only see them 2 times a year or so.
I figured they would want a nice meal in town so we wound up at Red Lobster.
See ya

[hobieboy]

With your smoke, I suspect your turbo is marginal hence oil is blowing thru the seals?

I typically keep my oil level half way between min/max. Not below min.

Did you check your mixture? How rich/lean are you running? Not sure if that has something do with your 4500-5000rpm stumbles.

[mmastro]

Have you removed your IC and checked how much oil your turbo is puking into your intake plenum? My guess is that you'll be able to "pour" out a decent amount of oil from your IC. That means your turbo's bearings/seals need a rebuild and/or your shaft may be toasted.

You shouldn't be consuming that much oil on a track day. I do as hobieboy does...half way between the max and min marks on the dipstick for track days (and pretty much the rest of the time, too).

What's the rebuild history on your motor? Any mods that you've done, also? Valve guides? Piston rings? Does your motor usually smoke upon startup (normal driving day)?

Hopefully, the turbo gurus will chime in soon.

[fredmeister]

The engine does not smoke but a puff on normal startup and does not use any oil while street driving. It only smoked badly after each track session.
The turbo was rebuilt (I have receipts) a few thousand miles ago....previous owner provided documentation....don;t know if engine was rebuilt though.
Is it possible to be coming from the oil tank breather for the turbo oil catch tank?

[rennsportman]

Hi Fred,
Glad to hear you found a 930. I would put money on a bad turbo causing the smoking.....most likely the IC is full of oil. I hope it's only this, otherwise be prepared to empty your wallet!