Leon Speed

Inspired by the many breather threads I made some modifications to my breather system. It is a Shark Vent from 928 Specialists, I added a fresh air line and made it a closed system.

For the fresh air line I used the original rear passenger side breather hose. I added the largest check valve I could find (from Boomba Racing) and routed it around the air filter box towards the drivers side.












To close the system, I connected the Pro Vent air out to the breather hose from the oil filler neck to the MAF elbow, using a 1" to 5/8" reducer.



Anyway, here it is, hope it works. Just throwing this out there for others who might want to do this.

yardpro

wow... that is a super clean engine bay....

Ducman82

very VERY clean... almost ROB clean...

IcemanG17

my opinon on "breathers" is this:

VENT TO ATMOSPHERE......I have raced 928's for years and my answer is a simple answer is to vent the crankcase to atmosphere.....I have done it twice and it WORKS....sure its not "smog" friendly but my engines last and run for a very long time under racing conditions, which are significantly more harsh than street driving by quite a bit.... My answer is simple and this:

1: Vent crankcase to atmosphere through the 16V oil separator top vent..DO NOT allow any oil vapor back into the intake...it has no business there
2: Run an "OB" oil pan with 3/8th spacer....
3: Run quality oil for your purpose

that is all I do.....I have over 90 hours on track on well used engines.....all run perfect....

MGW-Fla

wow that looks like a new engine!

Cosmo Kramer

The hose on the passenger side that appears to go under the intake with the check valve, what is it connected to?

AO

Aryan,

I agree with Brian. It's better to vent to atmosphere - that what I do. Oil in the intake can cause knock. Although, with that separator (same one I have) I never have had any oil in the "air out" hose so maybe it's a moot point.

P.s. don't forget to hook up your coolant hose.

Lizard928

Brian,

You're sounding more and more like MK.

I run a vacuum pump on my car and it's WAY better than just venting to atmosphere which I still do. But the crankcase sees a pretty healthy vacuum which in turn seals the rings better.

IcemanG17

This is a good idea too...........of course the "poor mans" way of doing it is venting to the exhaust........I'd imagine that will pull plenty of vacuum...I think Carl tried it for a bit

Leon Speed

Yes a clean engine bay lot's of elbow grease during a top-end refresh and TB job. It will probably get dirty again when I drive it

Venting to air is illegal over here, think Carlifornia-rules. Although the chance getting caught is minimal, I'd like to avoid this illegal construction

Ted, the hose with the check valve is connected to the Y-piece that plugs into the MAF-elbow (as it is connected normally). The other hose at the Y is connected to the Pro Vent air outlet via the reducer connector.

This vacuum pump sounds interesting but how it would work with a oil separator?

Charley B

I thought any deviation from factory was illegal here in Cal., unless approved by CARB.

Lizard928

You require an oil separator to use the vacuum pump.

You would have to add the return line before the MAF or it would be too much unmetered air.

Leon Speed

Somebody asked me if my setup works. Just to leave some feedback here, I found that at higher rpms (5000) the provent is full of oil which indicates this setup works. At cruising rpms the provent is dry. I'm guessing my oil reduction has decreased by about one third.

Gary Knox

Aryan,

BOTH the engine bay AND the modifications look great. I'm in the process of modifying my '89 manual (track car) for use of the ProVent system, and appreciate your changes and posting these pictures as I finalize my approach.

Gary Knox

Alan

Interesting changes... I'd T in the small port on the OFN to the provent output also (tricky for spacing and size difference) - it sees a quite oily mixture so will still ingest some (small port though).

I imagine it works as well as the original sharkvent for typical street driving and it flushes with fresh air, and dumps nothing to atmosphere.

I'd be concerned that for high RMP/load/blow-by its worse than the stock set-up though - because you now only have one breather line into the TB ports vs 2 before - restricting Provent breathing.

Might be worth either:

1) Plumbing the Provent output to T with the other breather before your new check valve (via another out only check valve)

OR

2) Add an atmospheric "blow-off " valve (big check valve with 1-2 psi crack) on the provent OP so that any excess pressure will have a place to go.

You do have a built on OP BOV on the provent - but its in the cap so if it lets go you will have a very oily mess all over the Provent and probably dripping onto your belts

Nicely done though - and I agree with the idea of fresh air flushing and evac back to the intake. If the Provent is working well (and except overloaded or constrained - it seems they do) you should have very little oil remnant in the separated flow.

Alan