I ran a DE event last Tuesday at Laguna Seca. After 2 sessions totaling 45 minutes, both oil separator tanks filled and I ended up with a mess under the hood.

We know the GTS is prone for higher oil consumption, but pushing out over a quart in 45 minutes seems excessive. The engine is a fresh rebuild by DEVEK with the Vortech only running 5.5psi at redline.

Any comments would be appreciated. How can I catch the oil and return it to the sump while under WOT.

ps. I was running low 1:50's.

Thanks!
Joe

 

Im not sure what MY it changed but on my S4 there is a small metal plate on the top/front of the oil pan. I took it off drilled a hole in the plate and added 2-3" long 1/4" steel tube. Take the drain from your catch can and return it there?

Just an idea.

 

Joe I suspect you are just the only one admitting this. Tony is right, the pan hole is a good return. But ultimately GTS engines are often blowby-ers, and that's just how they are. It is CRUCIAL that you not allow that oil to hydrolock your engine as we've had one locally do. If you leave the stock system in-place that is what would happen.

 

Tony it changed in '87. Early vs late '87.

 

DR made a special dip-stick tube with a "Y" welded in the middle to allow any oil to drip back in. There's a little check valve just in case the oil wants to come the other way, but I think it would probably blow out my dip stick if that ever happened. Works so far.

Oh... I should note that I am using the Pro-Vent separator, and I do not track my car... yet.

 

All of my oil blowby, and I have lots of it at over 6000 RPM, is from the oil filler neck breather. None comes out the cam cover breathers.

Marc worked pretty hard to devise the breather system you have, as I recall. He must have some ideas about why it is not working very well, especially with the drip back system. I would guess the area it is draining into is also under pressure. I'd rather keep the oil internal while still venting the crank case pressure, avoiding external separators and drip-backs but no one has figured that out yet. I think even the elaborate scraper systems are not 100%.

What about dry sump?

 

i think that the problem will still exist while the crank case is pressurised by the blowby, any attempt to return oil there will be met by air/oil vapour coming the other way ie. any further hole added to the engine will just act like another vent?? joe, i cant remember if your car has 951 pistons in it with custom rods.. thats right its stock internaly but has had some head work, with headers too.

 

Joe
1 quart in 45 minutes at track pace for a supercharged GTS really doesn't seem that bad.....I'm sure marc thomas has some good ideas on how to reduce it! I think that is about how much oil George uses in his S/C ORR car!!!

 

This change was made when the 32V engine was intriduced. The '85 has a block off plate and the '83s have a tube.

 

Tony - I have the crankcase line, but only the Vortech's return line uses it.

Andrew - I'll research the the Pro-Vent.

Bill - Marc's tank drains back into both valve cover holes. Yep, under pressure.

Nick - I agree about the pressure. I may have to just live with draining the second tank after each session. I have stock pistons & rods now. I had to get a fresh factory short block due to the fire and cracked cylinder. I don't think Marc drilled the piston oil return holes either, but I could be wrong.

Brian - I'll probably get a larger 2nd tank or make sure I drain it all the time.

Thanks for all your comments!!

 

My GT used about one quart the last DE in Sebring in 8 track sessions totaling about 4 hours (pedal to the metal... )
Under "normal" street driving I use about a quart every 1k miles.
I still have no catch can, just goes straight out. I would really like to find a good solution in order to minimize polution.
Seems quite a bit more in your GTS, but then again, I have heard the GTS uses lots more oil from the get go.

 

I agree based on oil consuption I see on DE weekends with other 928's.

Reason why a few of us are looking into dry-sumping.

 

Joe, I've been through similar venting stuff in the past and may be able to offer some ideas. I went through several breather configurations on a pushrod V8 car that generated blowby on track. The 2 things that I believe helped greatly were large diameter/volume tubes and my secret baffling material. The baffling material I use is from a floor polishing pad, non abrasive of course, I can post pics and tell more later if you'd like, there are some things that may apply even though it was a different engine. Do you have any more pics and details of your breather system?

 

I was thinking dry sumping would only help part of the oil ejection - from the oil filler breather. But does oil cloud around the crank also get up into the valve train area and does dry sumping eliminate that?

 

I was thinking the same thing about my oil ejection issues. The breather tubes and orifices in my SC kit are so small the air velocity must be very high and occlusion much more likely leading to potentially huge loses at very high RPM. Same with the stock set up. So, I was planning on opening up some of the breather orifices and using larger diameter hoses as well as adding a baffle below the orifices to try to keep more oil in the engine. Reducing the speed of breather vapor and making it harder for the passageways to get occluded by oil seems like it should help a lot. I pumped a quart out of the narrow oil filler breather in 80 miles at 145MPH average (top 170) speed.