DR

Hi John,

Thanks!

Concerning air Pump hookup, check Page 1, post #3

Alan

For an NA car is there any reason not to still use the throttle body vac port for partial vacuum scavenging on the provent outlet rather than just venting it via a direct filter? assuming the outlet gasses are pretty clean this seems reasonable (except for SC/TC) unless vacuum here will make seperation less effective (seems it was designed/limited for it though...)

If a goal is also to avoid going to negative crankcase pressures then would additionally venting into the the head covers via a check valve from a filter be a good solution to balancing this and possibly increasing the minimum flow volume through the Provent...

Just trying to understand all the rationale here...

I have what I consider excessive oil consumption & I will soon need to get my intake & head/cam covers refinished and I'd like to consider options for additional porting on these now for a Provent system (great to see it packaged up Dave). Beyond installing the dual ports is there any obvious place where an additional in only (no seperator) port could be fitted nicely - say in the middle somewhere near the cam chain?

...or is this all just a horribly bad idea?

Alan

GlenL

I vented my home-made separator to the air box. There were spare fitting and it tidied up the hole thing.

heinrich

SWEET Dave I bought a Provent from you but I would love the additional goodies ...

ROG100

Dave,
Awesome product and as always great service.
My GTS is no longer smoking thanks to Dave.
I highly recommend this product. Dave thanks for putting the kit together for us.
Roger

Alan

Roger - did you go with the standard install on the GTS? - did it reduce oil consumption noticeably (obviously less smoke would suggest so...) - any guestimate on % change?

Glen when you say airbox do you mean before the filter/MAF or into the existing throttle body connection?

Anyone any thoughts on more venting for the cam covers (e.g. air in only via check valve/filter)?

Seems to me this would avoid the risk of vacuum build up in the crank for a 'closed' system AND provide a continued minimum flow to the provent when there is little blowby - e.g. decel

Alan

heinrich

Alan,

I strongly believe after years of thought on the topic, that American 928's are at a disadvantage because tracks go anti-clockwise here, forcing oil to the passenger's side.

Also, I strongly believe that the windage sloshes oil up to the passenger's side.

And, where did Porsche put the little holes that allow oil to be sucked out? The Driver's side.

GlenL

I meant into the air box just underneath the filter. When I think about this more, I'd advise against that for MAF (S4+) cars. You just don't need oil vapor on the hot wire. For my CIS system it's fine. Flapping door people? Fine, too.

Road courses generally run clockwise. There are exceptions. And they all have turns in both directions. Who is running a 928 on a (boring) oval?

hacker-pschorr

Oil + Combustion chamber = increased chance of detonation

Detonation = increased blowby

It's a very vicious cycle - I would never vent crankcase vapors into the intake on a track car.


Road America is clockwise, 14 turns (9 of them right including the long sweeping Carousel).

How does this compare to other popular US tracks?

Alan

Erik - Yes - but I already have a bunch of oil/vapor getting sucked into the intake with the stock system - so with the Provent this should be hugely reduced... I would not plumb it ahead of the MAF - even though it should be much cleaner - why take any risks with any oil on the wire - and the Vac port is right there with a hose already on it...

For me its a GTS road car with significant oil ingestion to be fixed - not a track scenario. I'd also assume the California smog ****'s would not like the directly vented solution...

Alan

DR

Heinrich,

Not a problem, just give Jeannie or a I a call and we will hook you up!

DR

Hi Roger,

Wow, thank you for the feedback and you are very welcome!

I am so happy to hear your GTS is no longer smoking.. VERY COOL!!!!

Alan

I recalled reading a good article on oil starvation and indirectly oil ingestion... had to think where it was...

Well it came to me - it was Louie who has some ideas as implemented on his car and a link to a document by Mike Schmidt on the stock system operation (great)

I'm still re-reading Mikes doc and trying to get my head around it all... great stuff. I knew there was more to it that I couldn't remember...

Louie's full implementation is interesting (though no air/oil seperator) - I have no plans to extend to his sump mods any time soon.

So after reading that I'm thinking to feed air via check valves into both rear cam cover ports fed from below the filter in the airbox (easy routing). Vent the 2 front ports to the Provent but with restricted port sizes to force most flow down to the crankcase and use the big vent system for the crank at the filler. Then figure out the appropriate vacuum control for the Provent... still not sure on that after reading Mikes article...

Alan

DR

You can plumb the air out from the Provent back into the intake if you really want to. It will greatly reduce the oil going back into the intake, but not completely elimnate it. However the amount going back in would be very small and probably not noticable.

The only real down side I can think of is there still might be enough oil vapor to still cause the Idle stabilzer to starting sticking as it gets gummed up from oil vapors over time. That is one fo the unsung beauties of he SharkVent, as it elimates the oil vapors from passing thru the idle stabilizer at idle which IMHO leads to it getting gummed up and failing prematurely.

If you look at the Crankcase vapor fitting "Y" on the rubber elbow you will see the "Y" fitting for the air in of the idle stabilizer is directly across from it. This is partly why the old WD-40 trick can sometimes get the idle stabilizer working again as it cleans out the oil that is gumming it up.

Here are a few other easier solutions to do what I think you want to accomplish, without really going back into the throttle body..

Please check out Post # 3 (page 1) and #36 (page 3) if that doesn't answer your questions let me know.

Alan

OK - I've read through what Mike & Louie have said/proposed/done...

I'm thinking now that a better solution may actually be to port all 4 cam cover ports with air 'in-only' (from below the airbox filter) via check valves - basically similar to what Louie did. Then use Dave's Provent X style intake from the oil feeder only (basically equiv to Louie's cap) to get good feed volume to ensure the blowby venting is always direct from the crankcase and causing suction down the drain-back passages in the heads - avoiding any scenario where vapor wants to get pumped up those passages to exit...

Dave - you are quite right that the airpump path may make more sense and its certainly local & convenient there - however - I assume there won't be much actual suction there given the open filter is right above that area... whatever exhausts there will be sucked in by the airpump but isn't that about it?? can it actually generate high rpm suction when plumbed that way??

In cases of high blowby it seems the crankcase would pressurize, seperate through the provent & exit fine. But the rest of the time it seems the provent won't scavenge vapor much at lower load (without much blowby) unless there is a real vacuum source pulling it through... the stock system seems designed for continual suction into the intake at variable levels.

It seems there would be even more value in trying to actively separate the entrained oil rather than ingesting it - e.g. consider this: fuel cutoff on deceleration after a high load burst - crank pressure drops due to no combustion but there is still lots of entrained oil... there is no flow to the provent until you get back on the throttle...

A vacuum source directly related to rpm would be nice for the no fuel decel cases and also works for idle/partial throttle and then maybe a kind of blow off for the WOT self-pressurization.

So is there a way to restrict the airpump suction on its filter to get rpm related suction onto the provent (or am I missing something on how the airpump works...)

Does that make sense - anyone? It seems to make perfect sense to me right now...

Alan