Herman K

Mods are:

Using the same (3) factory installed orifices to regulate the ventilating flow rates the way Porsche had designed it for these engines

A custom designed Provent supply pipe incorporating a check valve to control the reverse flow in and out of the rear cam cover elbow.

A Provent oil separator with mounting brackets and a check valve for separated oil returned from the Provent to the crank case.

Hose (2) connecting to the Provent

IcemanG17

I just don't like any of the stock-ish systems.......oil has no business being routed BACK into the intake....its only done for emissions reasons & only causes problems..... Yes the stock breather for all of the 32V sucks.....the 16V is better due to its better seperator at the filler design that the 32V didn't use....the 32V design is pretty horrible for the oil filler....pretty much unrestricted crankcase pressure go straight up the filler and pressurize oil into the intake....

Yet another example of Porsche un-engineering 928's during its life cycle....

Lizard928

for a stockish system, yours looks pretty good. I personally like the vacuum pump I'm running on my car.
Not even a hint of a vapour of oil out of it.....

17prospective buyer

Iceman; if there were alot of rednecks here that saw it was just for emissions purposes, they'd be like "well **** you don't need that crap in the country! gotta put a quick n dirty road draft tube from my ole' Ford 302 Windsor motor on my Porsh-ee!"

Herman; kudos to you for trying to improve the system, i will have to do something about mine when it comes time to put it all back together. Did you do those cam covers in wrinkle red?

Herman K

Porsche used the principals of the Bernoulli Effect to recirculate the 928 crank case vapors back to the TB via the oil filler neck base on the early cars and OFN top for the later (GTS) models vent located at the PS top of the OFN.

By adding the Provent oil separator to the factory designed crank case vent loop vent loop oil and oil vapors are returned to the crank case and cleaner air is returned to the TB.

To see an interactive demo and explanation of the Bernoulli Effect go here > http://mitchellscience.com/bernoulli...iple_animation

The powder coating was done by Ben Genovese (a RL regular ) and they are light textured.

Gary Knox

Herman,

Your schematic picture above, as well as the design, layout, and installation of the HKR3 are beautifully done. At OCIC, during our discussion of it, you indicated that it might become available through Roger as a "kit".

Could you tell all of us who are interested in adding this to our cars "when" the kit might become available???

Cheers, and congrats on a very nice modification.

Gary--

Herman K

Gary,

The kit will be available in 2-3 weeks - thanks for taking the time to learn about it -

Herman

mdkelly1

Herman,

Added your breather system to my "list" as well. Also, liked your interior console prototype mod at the OCIC. Great innovation!

Thanks,

Leon Speed

Herman, nice pictures. I have more or less the same, inspired by your schematics. Only thing I have to figure out is how to connect the provent vent to air port to the throttle body hose. It needs a reducer from 25 mm to 14 mm. Can't see it really well in your pics but it looks you found a solution.

GregBBRD

Herman:

Interesting. This looks like you may have "patched" one issue. It is realy unfortunate that you "started" with one of the "mistake" GTS engines (explaination, below).

As we talked about, when you were "waiting" for one of my kits to be done (sorry the development and testing took so long...but I can't "rush" this stuff....I've got to be sure) my goals went beyond just wanting to remove the oil from the intake. I saw the "bigger" problem as the inability for the crankcase to properly vent and thus "restrict" the oil return from the heads to the crankcase....which causes an entire "cascade" of other problems.

For 20 years, I thought that Porsche/Mahle had "screwed" up by not drilling the oil return holes into the pistons on the GTS engines. It was a real "ah ha" moment when I finally figured out that they did this, on purpose. Bernoulli effect, or not, there simply is not enough volume to vent the crankcase through a 5mm hole. Porsche obviously realized this and therefore knew that with crankcase pressure, the oil would be forced "backwards" through the oil "return" holes and would therefore put more oil onto the cylinder walls. Therefore, they intentionally deleated the drainback holes. Interesting "experiment". What is perhaps more interesting is that they didn't test far enough to know this wasn't going to work.

The "problem" really gets bad, when one is unfortunate enough to get a GTS that has the "wrong" breather elbows.....like your car was obviously equipped with....and you based your design on.

Let me explain:

Pre 1992 engines (I'm actually going to leave the "early" 1992 engines completely out of this discussion....what a mess they were!) were equipped with a breather elbow in the front of the passenger valve cover that had no restrictor and a breather elbow in the rear of the passenger valve cover that had a 6mm restrictor (928 107 733 00 and 928 107 733 02). Note that both of these breather elbows are attached to the intake system. These two together had "marginal" breather capacity.

With the introducton of the GTS models that had the additional breather elbow on the front of the driver's valve cover, they changed the rear breather elbow and the front driver's elbow to a breather without a restrictor, at all (928 107 733 01). The "restrictor" was supposed to be removed, because they obviously knew that a mere 6mm hole wasn't going to be enough to ventilate the entire engine.

Then "production" started and thing turned to absolute ****. Many of the engines were "equipped" with the breather elbow that had the 6mm restrictor.....major, major mistake. These engines simply do not have enough "breather volume" (regardless of any "effect") to vent the heads and the crankcase (the entire engine venting is limited to one 6mm hole). I've been quietly "fixing" these engines, with this "mistake", for years. These are the engines that "really" used oil. You obviously (looking at your design drawing) had one of these "mistake" engines....and unfortunately based your design on a "mistake" engine.

So, regardless of what you do to "filter" the oil from the crankcase air, you still have the terrible problem of excess crankcase pressure, which "keeps" oil on the cylinder walls and thus in the combustion chambers and restricts the return of oil from the heads into the crankcase....causing the oil pick-up to be easily "uncovered".

Simply removing the restictor (which I've been doing for years) helps, but doesn't "solve" all of the problems.

These engines really need a complete redesign of the entire system. The early models 1987 to 1992 "pushed oil into the intake and still had marginal crankcase ventiation. The GTS models were a complete 'step" in the wrong direction.....wrong breather elbow, or not.

RKD in OKC

Greg, exactly were is this restrictor elbow and how to I fix it, my 94 GTS uses oil horribly and NO OIL IN INTAKE.

GregBBRD

Depending on what condition your rings are in will determine what results you get. All of the GTS engines need the oil drainback holes drilled into the pistons, when they are rebuilt....but only if the crankcase pressure is reduced!

My new complete breather system addresses the crankcase ventilation problem, the oil in the intake problem, and the associated problems of those things....and it is a "must" for all the GTS style engines.....in my humble opinion. However, if the rings are really "gunked" up from years of oil clogging, you've got a tough road. Once you get the crankcase to breathe, you might try an aggressive oil cleaning/varnish remover (Swebco 502) and see if you can "free" up your oil control rings.

You can start by pulling the hose that goes to the passenger rear breather elbow. Look inside. If there is a restrictor in there, you have one of the "mistake" engines. I've found "mistake" breather elbows all the way through to late 1995 models. It is almost like they randomly selected breather elbows, with complete disregard if there was a restrictor there, or not. It seems that whatever they had, on the shelf, they used.

Worth noting is that non-resticted elbows are, by definition, going to decrease the crankcase pressure, but increase the amount of oil that gets forced into the intake.

Unfortunately, the problem is complex....hell, Porsche couldn't figure it out! There is no "magic wand" repair. Look closely at my new "Ventilation Kit". It's complex and there are a lot of pieces involved, it's a pain in the butt to install (remove valve covers and intake manifold), and because of all the pieces, it's expensive. Believe me, if I could have solved this problem with a Provent filter and a couple of hoses, I would have done that.

Ed Scherer

Here are the two elbows; see the thread "Cam cover breather adapter elbow variants" for more information. If you have one of the restricted ones, it'll likely be on the left side of a valve/cam cover.


A ".00" elbow with the restrictor (and keyed to fit in left side of valve cover):




A ".02" elbow without the restrictor (and keyed to fit in right side of valve cover):




A ".02" elbow re-keyed so that it can be fitted to either the left or right side of a valve cover:

17prospective buyer

Greg would you say the crankcase ventilation system has always been a limiting factor in HP for 928 engines?

GregBBRD

....Only from the standpoint that most of the engines which make more power generally have had a reduced life span, because of these issues.....

Seriously, oil in the intake system is going to reduce the effective octane of the fuel and reduce the amount of timing that individual engines will tolerate. Many GTS engines will "ping" because of this (along with the increased carbon build-up.)