PVC solution for Boosted Motors
Thread Starter
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From: Republic of Texas
PVC solution for Boosted Motors
PVC solution for Boosted Motors
This is my solution for crankcase ventilation on boosted motors (especially older/high mileage engines) So far, the new setup has presented no problems and I’m awaiting a 6-7psi pulley to take advantage of the new-found potential.
The Original setup:
The New setup
Note: Those of you with the OEM pop up headlights will need to find another location for the Catch can. There is a well vented area just in front of the driver’s side firewall that would work with about 2 additional feet of PCV tubing.
This is my solution for crankcase ventilation on boosted motors (especially older/high mileage engines) So far, the new setup has presented no problems and I’m awaiting a 6-7psi pulley to take advantage of the new-found potential.
The Original setup:
The New setup
Note: Those of you with the OEM pop up headlights will need to find another location for the Catch can. There is a well vented area just in front of the driver’s side firewall that would work with about 2 additional feet of PCV tubing.
Drifting
Joined: Sep 2008
Posts: 1,389
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From: somewhere shooting my assault rifles
I do not run any line going to filter side of blower. I do not like the idea of any vapors/mist going through the blower and IC while cruising coating the IC with crap resulting in less efficiency.
While in boost in above diagram there is going to some oily mist getting by the catch can (and no catch can will catch 100% of the mist) and going through whole system before it even gets to intake.
I have a hose off the oil cap with a filter on it going to the ground so when in boost crankcase funes/pressure exits.
I route the catch can in line off valley pan and out line to where the stock PCV hose goes behind the TB (not the nipple right behind TB that has a cap on it in boosted apps but the nipple PCV line goes to) with a brass one way check valve in place of the stock PCV valve so vapors/oily mist gets sucked directly to intake while not in boost/cruising.
Every has a different way of doing all this.
While in boost in above diagram there is going to some oily mist getting by the catch can (and no catch can will catch 100% of the mist) and going through whole system before it even gets to intake.
I have a hose off the oil cap with a filter on it going to the ground so when in boost crankcase funes/pressure exits.
I route the catch can in line off valley pan and out line to where the stock PCV hose goes behind the TB (not the nipple right behind TB that has a cap on it in boosted apps but the nipple PCV line goes to) with a brass one way check valve in place of the stock PCV valve so vapors/oily mist gets sucked directly to intake while not in boost/cruising.
Every has a different way of doing all this.
Last edited by Z06supercharged; Jan 26, 2011 at 06:03 PM.
Le Mans Master
Joined: Aug 2002
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From: Houston TX
St. Jude Donor '11
Mmmm....I don't like it George. I have two catch cans running in series and the second one still catches oil so I'm sure it's still letting some by. No catch can is going to catch all the oil. With your setup you are likely to get oil all throughout the blower and intercooler. 
Also there is no fresh air source so it will be pulling in a lot of oil. You basically had it right before but you just needed a check valve to keep from pressurizing the crank case when in boost.
Catch can routing is a somewhat hotly debated subject but here is how I think it should be:
Tracy, who designed the old RevXtreme catch cans has a new one out that has three nipplese on it and check valves so that when the port behind the throttle body closes it uses the hose in front of the blower for a vacuum source (while under boost).
Also there is no fresh air source so it will be pulling in a lot of oil. You basically had it right before but you just needed a check valve to keep from pressurizing the crank case when in boost.Catch can routing is a somewhat hotly debated subject but here is how I think it should be:
Tracy, who designed the old RevXtreme catch cans has a new one out that has three nipplese on it and check valves so that when the port behind the throttle body closes it uses the hose in front of the blower for a vacuum source (while under boost).
Melting Slicks
Joined: Jul 2007
Posts: 2,087
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From: Austin TX
I currently have a breather cap but I am about to 'T' the driver side and passenger side VC together and run one line to a catch can with a breather on top of it. That or Im going to get a catch can with a breather with 2 inlets and run a line from the driver side VC to the pass. side VC. Will cap everything else off.
edit: kinda like the above but I dont plan on running anything to the intake or to the blower
edit: kinda like the above but I dont plan on running anything to the intake or to the blower
Le Mans Master
Joined: Aug 2002
Posts: 8,472
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From: Houston TX
St. Jude Donor '11
So thats a PCV delete. I ran similar to that for a while but I got oil mist out of the breather cap on the valve cover and a pretty bad oil smell. I just had everything capped off and had a breather on the valve cover. Now if I used a catch can with a breather on it, that may not have happened. This provides no vacuum to the crankcase, just a way to keep from building pressure. I think having the crank case under vacuum is better but I'm not arguing either way is better than the other.
Melting Slicks
Joined: Jul 2007
Posts: 2,087
Likes: 11
From: Austin TX
So thats a PCV delete. I ran similar to that for a while but I got oil mist out of the breather cap on the valve cover and a pretty bad oil smell. I just had everything capped off and had a breather on the valve cover. Now if I used a catch can with a breather on it, that may not have happened. This provides no vacuum to the crankcase, just a way to keep from building pressure. I think having the crank case under vacuum is better but I'm not arguing either way is better than the other.
I have a bad smell from my oil breather too when I have the recirculating air on so Im going to try to place this new catch can/breather under my radiator shroud so I wont get it as bad. Im getting my dip stick pushed out a bit so Im trying to let mine breathe more/relieve more pressure.
Thread Starter
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From: Republic of Texas
Mmmm....I don't like it George. I have two catch cans running in series and the second one still catches oil so I'm sure it's still letting some by. No catch can is going to catch all the oil. With your setup you are likely to get oil all throughout the blower and intercooler. Also there is no fresh air source so it will be pulling in a lot of oil. You basically had it right before but you just needed a check valve to keep from pressurizing the crank case when in boost.
Also there is no fresh air source so it will be pulling in a lot of oil. You basically had it right before but you just needed a check valve to keep from pressurizing the crank case when in boost.I'd like to do something like this: (note: the RevXtreme logos has been removed from this diagram so there will be no confusion if this image is referenced)
What do you think? My main concern is that under NA conditions the intake manifold won't have as much vacuum as the intake in front of the blower. Am I mistaken?
Also, can i get a 3/8" check valve at a local auto parts/hardware store or is this an online order type of thing?
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Le Mans Master
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From: Houston TX
St. Jude Donor '11
I didn't understand the need for a fresh air source either. This is a good but long read. The fresh air source is explained in post #6.
http://forums.corvetteforum.com/c6-t...cv-system.html
Any air in or out of the nipple behind the TB is unmetered air. Not enough to make it run funny but I did see a difference in idle air flow when I changed to a pcv delete.
Le Mans Master
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Le Mans Master
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Le Mans Master
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St. Jude Donor '08
I currently have a breather cap but I am about to 'T' the driver side and passenger side VC together and run one line to a catch can with a breather on top of it. That or Im going to get a catch can with a breather with 2 inlets and run a line from the driver side VC to the pass. side VC. Will cap everything else off.
edit: kinda like the above but I dont plan on running anything to the intake or to the blower
edit: kinda like the above but I dont plan on running anything to the intake or to the blower
Let me know when you do it and Ill get you some good pics. Mine is all AN and nylon braided hose
Tech Contributor
Joined: Apr 2007
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From: Forney Texas
I have been talking with Brian (aka GolfinZ) about this over the last few days and I am not a fan of putting a vacuum on the crancase and sucking oil into the intake. The time you would really benefit from a vacuum on the crankcase is under boost, yet the check valves are closed. I just don't want any crankcase pressure, so I too am an advocate of venting everything to atmosphere.
Drifting
Joined: Sep 2008
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From: somewhere shooting my assault rifles
On several of my other street cars ive owned I placed a header evac system with valves on the exhaust. Hoses off both valve covers ran directly to exhaust headers and scavenged crankase vapors/pressure under boost (the evac valves are not open while cruising). Of course you cant do it before the cats or on a muffler type system with sound packing but a glasspack type metal insides type like B&B bullets will work. Even 20+ psi there will be no crankcase pressure at all with exhaust scavenging it all out...
Last edited by Z06supercharged; Jan 26, 2011 at 06:45 PM.
Tech Contributor
Joined: Apr 2007
Posts: 10,924
Likes: 78
From: Forney Texas
On several of my other street cars ive owned I placed a header evac system with valves on the exhaust. Hoses off both valve covers ran directly to exhaust headers and scavenged crankase vapors/pressure under boost (the evac valves are not open while cruising). Of course you cant do it before the cats or on a muffler type system with sound packing but a glasspack type metal insides type like B&B bullets will work. Even 20+ psi there will be no crankcase pressure at all with exhaust scavenging it all out...
Drifting
Joined: Sep 2008
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From: somewhere shooting my assault rifles
Very few street cars can use it as it wont work correctly with a mufflered car unless its a straight through muffler type system with alot of hp but once WOT it works very well. We make enough HP it will work as exhaust velocity is very high BUT I'm not sure how efficiently it would work though if placed further back down the pipes past cats or o2's.
Last edited by Z06supercharged; Jan 26, 2011 at 07:00 PM.