My Custom Catch Can/PCV Setup

[bpestilence]

You can still maintain a single catch can if you use check valves to keep the direction of flow correct. With the surge tank under vacuum it can then pull vacuum through the PCV valve from the crankcase, and when the surge tank is under pressure the same check valve is held shut and any blowby gasses instead have to go through the other check valve into the intake.

What type you use depends on what you want, but a dual can is not THE ONLY WAY to get it done right.

And, FYI, a correctly operating PCV system isn't intended to remove blowby gasses, it is intended to prevent them by keeping the rings seated.

 

[lacroixdp]

And, FYI, a correctly operating PCV system isn't intended to remove blowby gasses, it is intended to prevent them by keeping the rings seated.

It is designed to remove blowby gases from the crankcase. No matter how well your rings are seated, you are going to have measurable amounts of blowby produced by your engine. It is a completely natural function of any internal combustion engine. Here is a quote from a Toyota technical paper explaining the functions of the PCV System in a vehicle:

During normal compression stroke, a small amount of gasses in the combustion chamber escapes past the piston. Approximately 70% of these "blowby" gases are unburned fuel (HC) that can dilute and contaminate the engine oil, cause corrosion to critical parts, and contribute to sludge build up. At higher engine speeds, blowby gases increase crankcase pressure that can cause oil leakage from sealed engine surfaces.

The purpose of the Positive Crankcase Ventilation (PCV) system is to remove these harmful gases from the crankcase before damage occurs and combine them with the engine's normal incoming air/fuel charge.

 

[habitatguy187]

Glad someone posted this thread, I fixed my pcv system btw, used two check valves, a T fitting, and a broke pcv valve on the valve cover to let more gases out, but the check valves are setup so that under vacuum air will still be sucked out of the crankcase. I seem to have a lot of blowby so this is just a bandaid until the engine blows, then it's rebuild time

 

[lacroixdp]

Glad someone posted this thread, I fixed my pcv system btw, used two check valves, a T fitting, and a broke pcv valve on the valve cover to let more gases out, but the check valves are setup so that under vacuum air will still be sucked out of the crankcase. I seem to have a lot of blowby so this is just a bandaid until the engine blows, then it's rebuild time

I'm at my parents house right now until Monday so I'm not really looking on here or my email. Bring it by next week and we can do a more permanent fix for your ventilation system if you want.

 

[gsxtasy]

There should be 5" H2O vacuum in the crankcase. At best you will have 0.

WTF Eh?

 

[redline6k]

OP looks good. What did you do for baffling on the inside.

 

[slowgsr]

no baffling.

I felt it wasn't needed. Normally on cans, that are closed loop use baffling to help catch oil from the vapor, and than the vapor returns to the engine, however mine is strictly just a vent, and any oil that accumulates just drains back anyways.

Im not really sure how much oil goes though this thing either, since i also removed the baffling in the valve cover as well, so there is probably a considerable amount of 'spray'. Its doing its job though. 25+ psi pulls on a S258 in 4th, track passes, everything.. dipstick never budges, last year on 20lbs it was common for it to pop out.


I change the oil ever 1000km. I don't drive the car often either.

Thanks for the interest.

 

[604CruisinCroat]

Hey I know the 2 catch can setup is ideal, but I wanted to know if this way (see diagram) is ok with an additional check valve inbetween the valve cover and intake pipe?

 

[badas93tsi]

I've always been tempted to use one of these kits modified to work with our cars. The exhaust creates the vaccum and gets rid of the oil/vapor. I dont see why it wouldnt work, but I could be wrong. Any insight?

Moroso 25900 - Moroso Crankcase Evacuation Systems – SummitRacing.com

 

[romeen]

Hey I know the 2 catch can setup is ideal, but I wanted to know if this way (see diagram) is ok with an additional check valve inbetween the valve cover and intake pipe?

No, that's not a good idea. The hose between VC and intake pipe needs to be able to flow air in both directions.

While under boost (when PCV is closed) the high velocity air rushing through the intake pipe is what removes the blow-by vapors from the crankcase.

When in vacuum the blow-by vapors are being sucked through the PCV valve and into the IM. The fresh air that is needed to replace this is provided through the VC/intake pipe hose.

 

[7"exhaust_tip]

What about a setup that utilizes the "krank vents" and a catch can? (or possibly two)

 

[bboyalan]

What about a setup that utilizes the "krank vents" and a catch can? (or possibly two)

That is what I stated using in post#24.

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I have two Krank Vents; one for each oil catch can.

 

[seminoles2005]

PCV improvements and testing for DSM - Car Videos on StreetFire

 

[turboglenn]

WTF Eh?

THats' what i was thinking

 

[AndrewD5418]

That is what I stated using in post#24.

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I have two Krank Vents; one for each oil catch can.

Do you know of a place that sells them at a good price?

 

[bboyalan]

Do you know of a place that sells them at a good price?

I purchased mine from a 3/S specialty shop, but they can be found almost anywhere. Dejon has them listed on their site here.

 

[AndrewD5418]

I purchased mine from a 3/S specialty shop, but they can be found almost anywhere. Dejon has them listed on their site here.

Damn that's expensive. I'm thinking the plastic "Check valves" will work just the same, just not look as nice?

 

[cburke23]

Are you guys removing the PCV valve when going to a catch can? Only asking because on a Honda, that is what we do. I will be fabricating my own catch can here soon and will either be doing like the first post and welding an AN fitting or running 2 hoses from the v-cover and one from the intake on the turbo.

As far as contaminating the oil, if you are not running a return to the motor and just using the catch can to hold the oil and emptying it, you should be fine.

Ill try to clear some things up.
I removed the baffling in the valvecover, however no oil will come out of the breather filters, I have a -8an drainback, so any oil that gets collected will drain back.

So eveything is so far so good with removeing the baffle? I alway put that back when doing a Honda v-cover, so just wonder how everything it going?

 

[cburke23]

Here is the set up I was thinking of building. If I can take the PCV away for DD use then I will not need to run another line to the catch can.

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Sorry so small

 

[Calan]

I just posted an article that may help someone out. Posting the link here for future reference.

http://www.dsmtuners.com/forums/articles-engine-fuel/366890-4g63t-pcv-system.html

 

[97gst_spyder]

Great write up!!!

 

[BeatupVR4]

Looks to me like there is no vacuum involved in this system. So basically it is just a vent. For maximum performance (and minimum emmissions) There should be 5" H2O vacuum in the crankcase. At best you will have 0.

Here is a pic of my system:

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Notice that I still use the vacuum port on the intake manifold. I just use 2 PCV valves (for more flow at the same vacuum) and ran a simple catch can.

VERY nice setup! I hope it's ok that I steal this design?

 

[Calan]

VERY nice setup! I hope it's ok that I steal this design?

I wouldn't, but maybe that's just me

 

[slowgsr]

PCV is just a check valve, since you aren't pressurizing the catchcan you don't need the check valve... Meaning you aren't using a vac source to help 'evacuate' fumes.

BTW, my catchcan pictured in this thread is now for sale.