Catch-can vs. Oil Separator vs. Atmos Vent

[993Speedster]

Finishing up the very last bits of the turbo build and it's time to sort the PCV/crankcase vent setup so I'm not pumping boost into case and brake booster. As I see it, I've got 3 options (with the stock setup not being one; at least in its current configuration):

1.) Catch can introduced into crankcase vent tube and catch can outlet routed to turbocharger compressor inlet.

Pro's of this setup include: cheap, easy and readily available, largely keeps oil out of intake tract
Con's of this setup: tank has to be periodically emptied depending on tank size and blow-by amount, also even though oil is separated you're introducing "dead/oxygen-less" air into the intact tract + some grime. Blow-by gasses are hot also

2.) Oil Separator (looking at Mann & Hummel ProVent 200 as everyone raves about them) put in same location as catch can.

Pro's: Still readily available, keeps oil out of intake, doesn't have to be emptied and less loss of oil level in the sump as time goes by
Con's: More expensive than a usual catch-can and requires filter media replacements every so often, still introduces hot, oxygen-less blow by into the intake taking up space of precious cold-dense intake charge.

3.) Crank vent to atmosphere (w/ or w/o a tank to catch vapors)

Pro's: cheap, easy, keeps the turbocharger and intake tract the cleanest, ensures only fresh oxygen-rich cold air is going into turbo. From what I've been told, 3-5% alteration to tune for MAF based cars that switch to vent instead of re-circulation... so it's a sizeable increase in fresh air flow
Con's: very obviously not emissions compliant but the car doesn't have a cat anyways sooooo.....


I'm leaning towards 3 because.... well because racecar?


I'd love to hear all your thoughts and what you're personally running and why...

[jbrown]

I have a catch can and then it vents to atmosphere. I check it about ever 6 months and it is almost empty.

[T77911S]

I would think the 930 has some sort of check valve in line to the brake booster since the vacuum comes directly off the intake manifold that would block boost. could be wrong, never looked at it.
at the very least you should have a check valve that holds vacuum on the booster.

for the crank case vent, you should be able to just run a hose from the oil tank to a catch bottle. I have one from summit racing that I use since I don't have the stock air filter on. I would not vent to atmo.

[Bucketlist]

Had a drip tank for a while but the tank was still empty a year later so I replaced it with a filter. Works fine.

[Uwon]

If you are tracking, then this is the best way to avoid an oily motor and compartment at the end of the weekend!
M2CW
Johan

[flightlead404]

Originally Posted by Uwon

If you are tracking, then this is the best way to avoid an oily motor and compartment at the end of the weekend!
M2CW
Johan

Is that originally a paint spray can?

[T77911S]

no. looks like the one I have from summit racing.

I thought about doing that with mine but then if you just drain it to ground why spend the money on the can.
I would not think it a good idea to put oil on a track.

[stownsen914]

For two different NA 911 racecars, I’ve put the crankcase vent to the oil tank, and then vent the tank to a catch can (with a breather to atmosphere). I haven’t had to empty the catch cans after many years of driving on the track. If you go straight from crankcase to a catch can, try to run the hose as high as possible - it gives any oil a chance to deposit and drip back down to the crankcase instead of ending up in the catch can.

[Uwon]

Originally Posted by T77911S

no. looks like the one I have from summit racing.

I thought about doing that with mine but then if you just drain it to ground why spend the money on the can.
I would not think it a good idea to put oil on a track.

You are incorrect. There is a butterfly stop between the can and the hose at the bottom. It should be normally closed and you empty it periodically, usually in conjunction with oil changes.
Johan

[krasuskyp]

cheap easy catch can

don't vent to atm - bong-resiny oily mess ftl

[flightlead404]

On a related note, what about the oil sump for the turbo charger. I have one from Brian and it came with three fittings; a hose barb, a plug, and one with a sintered insert that is a vent.

I originally had the hose barb with a vent line running to my catch can as per original.

I later replaced that with the vented plug, but I don't like that because when I park on a left-leaning slope I sometimes get oil draining.

Is there a downside to just running a solid plug and not venting the turbocharger oil sump?

[pkabush]

Originally Posted by krasuskyp

cheap easy catch can

don't vent to atm - bong-resiny oily mess ftl

Exzacery.
And like many here have noted, it’ll be empty unless you track it.

[Rich76_911s]

Originally Posted by flightlead404

On a related note, what about the oil sump for the turbo charger. I have one from Brian and it came with three fittings; a hose barb, a plug, and one with a sintered insert that is a vent.

I originally had the hose barb with a vent line running to my catch can as per original.

I later replaced that with the vented plug, but I don't like that because when I park on a left-leaning slope I sometimes get oil draining.

Is there a downside to just running a solid plug and not venting the turbocharger oil sump?

My oil sump for the turbo (that goes to the scavenger pump) doesn’t have any ventilation at all. It came from Fabspeed that way. I’ve had no problems running it that way.

[T77911S]

Originally Posted by Uwon

You are incorrect. There is a butterfly stop between the can and the hose at the bottom. It should be normally closed and you empty it periodically, usually in conjunction with oil changes.
Johan

yes mine has the drain valve. I could not see It at first on your pic.
I though you had removed it and had it open all the time.
sorry.

[Uwon]

Originally Posted by T77911S

yes mine has the drain valve. I could not see It at first on your pic.
I though you had removed it and had it open all the time.
sorry.

No worries. It always manages to collect some water, more pronounced in cooler weather which encourages condensation. The can keeps the garage floor cleaner too.
Johan

[boosted79]

Plastic can off an '88. Just a plug in the drain tube with hose clamp. Works great.

[patkeefe]

Uwon, what size are the in and out connections on your Moroso can? I have one with AN-12 in and out, which I am going to try to use on my turbo SC. Mine is mounted in the same spot as yours. I am likely not going to track the car again.

[Capt Bob]

I put a fabsport breather on my 930. Works fine for me, however I don't race.

[Uwon]

Originally Posted by patkeefe

Uwon, what size are the in and out connections on your Moroso can? I have one with AN-12 in and out, which I am going to try to use on my turbo SC. Mine is mounted in the same spot as yours. I am likely not going to track the car again.

25.5mm

[OldSpool87]

Originally Posted by krasuskyp

cheap easy catch can

don't vent to atm - bong-resiny oily mess ftl

Friends don’t let friends vent to atmospere.