Just got the car broken in and am driving her hard to make sure everything is holding together well. I am getting oil blow by under high boost (14 psi) and high rpms (6-7k). I came to find that I am running a PCV valve (mechanic put it in), and that I am not venting the system to the level that I should be.

The two solutions that I am considering are just venting the oil filler neck straight to the atmosphere, or getting a catch can. If I go with the can, I do not really want to run one side of the can to the intake track. I don't care for this as hot oil/gas vapors will get into the intake track. So, either way I go I am leaning towards venting to the atmosphere.

After reading through many posts on the subject it seems that the downside to venting oil system pressure to the atmosphere is that the oil pan will no longer be under vacuum. What is the exact problem with this? Does vacuum somehow help oil flow better?

Thanks,

Matt

 

I think they are talking about the oil system being under vacuum to help extract blowby gasses. The only other problems with venting to atmosphere is oil can be spit out all over the engine bay and the gas and oil smell of blowby gasses. The oil puking can be stopped with a good catch can setup.

 

try venting to the atmosphere first and if you get a mess then try using a catch can

 

I'll probably just get a catch can regardless, they are cheap and I don't want a nasty mess in my engine bay . I will still vent it to the Atm though.

I'm mainly just wondering what the problem is with not keeping the oil pan under vacuum?

 

Many factory turbo cars pull a vacuum on the crankcase to help pull the oil from the oil drain tube of the turbo.

I was getting a little bit of blowby on my 4AN feed-10AN drain setup so I plan on running a vacuum line to my air filter from my engine.

justin

 

Mine does both. I have both lines from the oil filler neck going to a catch can that vents to atmosphere on top through a small K&N filter. I do not have any smell or oil spill/spray problems. My GT35R runs fine like this without any smoking.

In hot weather, there is very little condensation in the tank. In cool weather the condensation increases.

This setup keeps all that crud from going through the turbo and intake track where it messes it up.

 

you can also run the vent to the exhaust. . . there are even kits in summit to do so. the exhaust will help keep all that junk out of the enginebay and allow you not have to run a catch can and not have to run anything to the front side of the turbo.

mine is vented to the atmosphere. . . cause i got rid of my catch can. . . it filled up WAY too quickly. oil gets EVERYWHERE. at first i thought i had a major leak. . . then i realized i did. . . eheh, the vent is right above the area. i was planning on putting a filter on there, but may run it to the exhaust to keep all that out of the area.

paul

 

Your engine might be tired if you are making that much blowby.

I've made about 50 20+ psi pulls and have about 1 inch of blowby in my 'catch can' which is nothing more then a old waterbottle.

 

Got it, Thanks. Is this an issue with most single turbos? I don't know the size, but I have a pretty large drain tube on my turbo (maybe 1" diameter), this should be sufficient, right?

 

Yes this is the issue with almost all turbos. If venting the the atmosphere isnt enough and you are hell bent on not runing it to your intake you can get a vacume pump from Summitt racing, ect. It will draw a vacuum on your oil pan then you just run the other side of the pump to a catch can and atmosphere. Its belt driven...I THINK there are also electric ones but I dont know where you would find one.

Stephen

 

Hi Stephen, when you say "If venting to the Atm is not enough...", do you mean that it's not enough to alow for proper oil drainage from the turbo?
how do I know if venting to the atmosphere is not allowing my turbo to properly drain oil?

Thanks.

 

I think the way to go is to do the Crispy vent. The idea behind it is that if you vent both sides of the oil pan regardless of which way you are turning there shouldn't be any pressure build up. No pressure in the pan means better oil draining and no pushing of oil out anyplace even under sustained g loads.

Since you have a single there is a secondary turbo oil return line on the back iron that is blocked off. You take the block-off plate for that and thread in a 90 degree elbow/barbed hose fitting. Then run a oil safe hose (use some heat resistant wrap/tubing near the exhaust) to a catch can. Run a second hose from the oil filler neck barb to the catch can as well.

I used a Jaz catch from summit for a while which has 2 barbed inlets that worked nice for the two lines. I was getting excessive fluid with my old oil that was filling the can in a single track session, so I ran the outlet of the Jaz to a secondary 1 quart catch tank that I mounted to the side of the engine bay. Problem solved.

 

ALL cars pull vac from the crankcase to remove gases than can eventually break down/decrease oil life regardless of whether they're forced induction or not.

My $.02 says you're on a tired motor. After the first year of my single, I had no issues what so ever. This past spring I started to get a lot of blowby. Everytime I'd get on it and then let off it was like a smoke screen. I installed a catch can in the same fasion (sans turkey baster) as Triple-R. Worked like a champ. You won't have to worry about making a mess or anything. I didn't have the bottle fill up as much as I thought it would either.

As far as the drain line...I have a -10 coming off at 90 deg straight down. Most say that should be sufficient. I haven't had any issues since.

 

run a vented catch can, no point in pulling vacuum through the intake or exhaust. if you're getting blowby, it means that the crankcase is getting pressurized. since the vented can is atmoshperic pressure, you have a negative pressure differential anyway. you are in essence pulling a vacuum through the crankcase since the catch can is at a lower pressure than the crankcase.

 

can will prevent that?!?!

turbo sucks thru can to the oil filler neck...so the junk stays at the bottom of the can.

 

^nevermind, I see what you are saying now...I don't have any problems running it this way.

 

dubulup, I'm confused, are you venting to the Atm or not? Thanks for the pic, what can is that?

Matt

 

Filler neck ---> catch can ---> turbo intake


not atm.

 

but your still putting oil/gas vapors into your intake. Which could possibly mess with tuning?


Also there is no need to use both nipples on the filler neck right? Which one do you guys use?

 

break open your OLD black plastic one take out the charcoal filter inside and run the CAI return line behind the charcoal filter.. or get a breather mask filter for hydrocarbons and such, don't forget to run your gas tank breather to the snot can as well..

the filter will remove the HC's leaving you with much cleaner 'air' going back through the turbo

 

but is this necessary. Is pulling a vacuum on the crankcase needed or can it just as effectively just be "vented"

If the only downside is possible oil degradation from slightly more fumes remaining in the crankcase I'm not too concerned since I change my oil every 1000 miles.

 

^ I use the one that points down.

It could mess with tuning a little, but its cleaner than running the line straight to the turbo inlet...how stock is set-up. I did this for several thousand miles and I noticed a thin film of "yuck" on the inside of my intake pipe, adding the can helped that tremendously.

I also run fuel vapor recovery into the UIM...that is suppose to mess with tuning a bit too.

My concern isn't tuning however...it's passing emissions, and I wonder if I vent these things to ATM, if I'll get closer to passing?!?! worth a try, I guess. no more fuel vapor from the fuel tank and no more oil/gas vapor from the crankcase = better #'s thru the engine, but not better for environment, haha!

 

I friends car would smoke on boost when both nipples were capped...he vented one and problem solved.

I think vacuum on the crankcase helps but not needed...based on what I've seen.

 

I'm not venting either into my engine, both going to atm, yet I do it for simplicity and to keep a clean intake stream. I keep my car registered in one of the few areas that hasn't adopted full emissions testing yet. Just a visual check, and I have "a guy" that takes care of that .