GregBBRD

From what I've seen, most of these cars seem to be using "pre 1957" technology and are venting the crankcase to the atmosphere....got to love that!

Seems like as soon as the manifold was to see pressure, my stuff would blow up like a balloon.

hacker-pschorr

That's why boosted production cars have check valves to prevent the boost from entering the crankcase breather system.

Unless you route the output from your separator to the inlet of the compressor (turbo or supercharger). But if your compressor intake sees any significant amount of vacuum, that might not be good either.

What did the 944 Turbo race cars that you worked on do with the breather system?

GregBBRD

The 944 GTR vehicles were all dry sumped, so the tank was the vent. Hot rod951 vehicles (and stock ones) always used the stock ventilation stuff....and filled the entire intercooler and intake full of oil. The 911 engines always vented the dry sump tank to the intake system. And if there wasn't oil dripping out of the intake system when the car was shut off, you probably didn't have enough oil in the tank....

That's probably why I never really "freaked out" about all the oil in the 928 intake system. Seemed normal.

Hell, if the glorified lawnmower engines and the fastback Audi's all had oil in the intake, why wouldn't the 928 engines?

hacker-pschorr

Same here. I took the intake off my mothers Jaguar last week....pool of oil at the bottom. 185,000 on the clock and still going.
Same for my SAAB, the Audi's........

mickster

The oil in the intake increases the speed of air entering the intake and results in 30HP increase. That and I have a bridge for sale in Brooklyn!

Seriously though, this is one of those things that amazes me about some of the core members of the 928 community-continually improving a car that hasn't been in production for 17 years-almost the same amount of time as its lifespan. Incredible.

17prospective buyer

What's so bad about improving it? The investment into improvement of these cars, lists/forums, and events is what keeps these cars going. Just look at how little it takes to write these cars off cause they're technically worth about the same as a Corolla. If it weren't for the stuff i mentioned, these cars would be rare, and ironically probably worth alot more too. Funny how that works out eh?

hacker-pschorr

Who said it was a bad thing? Just an observation comparing the 928 to other cars.

I'm actually looking into an improved air / oil seperator system for the Jaguar and SAAB.

034 Motorsports sells such a kit for the 1.8 turbo VW / Audi crowd.

The Corvettes I prep / work on at the track all have improved breather / seperator systems since the stock cannot handle track use without blowing oil smoke out the tail pipe. Well, except for the factory dry sumped models.

Vilhuer

Thats not only difference between '92 and '93 GTS engines.

pcar928fan

Tell me more Erkka! Seriously I thought they ('92 and at least early '93) were the same...

Vilhuer

'92 ROW = early '93 US. '92 has block halfs mounted together with studs and nuts while '93-95 use bolts. Also pistons are different between them IIRR. Difference isn't large and they are interchangeable.

fbarnhill

Greg, this thing looks awsome. Why leave out the earlier 85/86 32v cars. I am already seeing an inssue with just 1300 miles on rebuilt engine. Puff of smoke when you nail it and small (maybe 2tbs) of oil in the valley.

Rob Edwards

My late 93 U.S. GTS engine (85P00656) had girdle bolts, but it had the 'early GTS' breather set up. No idea about which elbow subtypes were where on the driver's side valve cover, but the engine sure consumed a lot of oil before I killed it.

There are at least 2 iterations of the breather setup on GTS's. The OP's '92 and my '93 had an '08 filler neck, and the 928 107 312 00 hose running from the cam cover to filler neck as well:



'08 neck:




Note the bolt/plug/thingee molded into the nipple on the base, to block off one of the outlets:



Pretty sure that both the -08 filler neck and 312 hose are NLA.

I ended up using the -08 filler neck on my stroker, as it was a convenient way to re-route the breathers as Greg intended.



Just for completeness/crossreferencing, Ed Scherer made a nice post about valve cover breather elbows here:

https://rennlist.com/forums/928-foru...-variants.html

GregBBRD

Didn't leave them out. I'll get to them. Time and money to invest in products is the limiting factor.

GregBBRD

Thanks Rob! That's exactly what I was looking for!

So that is the 1992 and "early" 1993 version of the breather system. Note that the filler neck has an unrestricted "upper" hose fitting and there is a hose that runs directly from there to the valve cover. They were venting the crankcase directly into the valve cover!!!! (This is very significant, as you study what is happening). There was a single hose hooked to the intake that ran from a restricted valve cover elbow.

Talk about building crankcase/head pressure! A V-8 engine with all the breathing through a single 6mm hole!

Got to love that bolt blocking off the lower port!

Mid 1993 added the other breather elbow on the driver's front, superceeded the passenger rear breather elbow to the non-restricted version, changed the filler neck to a restricted version (and plugged the lower port with plastic, instead of a bolt), added the cross-over hose, and added the hose that runs from the oil filler back to the "Y" connector.

Truthfully, I thought that I had a pretty good idea of what Porsche had done and why they had done it, right up to the point where I ran Andy's engine at WOT above 5,000 rpms and saw what happened after 30 seconds of running.

I literally then brought Andy's engine back here and just stared at it, trying to figure this all out, for about 2 months. While I knew that the only solution, for his engine, was to "remove" the oil from the heads, I figured out how to ventilate the "street engines" at the same time.

That is this new Ventilation Kit.

jthwan22

Too bad my supercharger sit at the space for Pro vent