Crankcase Ventilation Q..
Thread Starter
Melting Slicks
Joined: Feb 2002
Posts: 2,298
Likes: 1
From: Sodertalje/Sweden
Crankcase Ventilation Q..
How is your ventilation system set up? PCV and a breather?2 PCVs going to the manifold?PCVs to the airfilter? etc etc..
I was thinking of using one PCV connected to the bottom of my airfilter and a open breather..
Any suggestions? :cheers: :cheers:
I was thinking of using one PCV connected to the bottom of my airfilter and a open breather..
Any suggestions? :cheers: :cheers:
Safety Car
Joined: Feb 1999
Posts: 3,631
Likes: 14
From: Fountain Hills AZ
Re: Crankcase Ventilation Q.. (BB wowbagger)
PCV needs vacuum to function so it should be connected to the carb. A manifold fitting would also work but the carb is preferable because it distributes the fumes more evenly. The vent side can be to the air cleaner or a separate breather. The advantage of venting to the air cleaner is that fumes are reburnt instead of escaping to the atmosphere (and leaving an oily film in the engine compartment).
Race Director
Joined: May 2000
Posts: 12,712
Likes: 2,264
Re: Crankcase Ventilation Q.. (BB wowbagger)
The purpose of a PCV system is to prevent the release of blowby gas - most of which is unburned fuel and air - to the atmosphere and also to ensure that blowby gas is purged from the crankcase before it can condense. A properly designed and functioning PCV system is a benefit to any engine.
Most PCV systems have a valve that meters flow and the metered flow is usually greater than the expected or actual volume of blowby gas. This allows the system to have a fresh air inlet to draw fresh air into the crankcase to both dilute blowby gas and ensure the system flows one way.
PCV systems should have suitable liquid vapor separators to ensure liquid oil is not passed through the system, and on a carbureted engine they MUST HAVE suitable flame arresting features to prevent a backfire from propagating into the crankcase and EXPLODING the blowby gas. Such safety devices usually consist of an anti-backflow feature built into the metering valve and/or a flame arresting screen on the fresh air inlet if there is a chance that flow could reverse.
Duke
[Modified by SWCDuke, 3:50 PM 3/16/2004]
Most PCV systems have a valve that meters flow and the metered flow is usually greater than the expected or actual volume of blowby gas. This allows the system to have a fresh air inlet to draw fresh air into the crankcase to both dilute blowby gas and ensure the system flows one way.
PCV systems should have suitable liquid vapor separators to ensure liquid oil is not passed through the system, and on a carbureted engine they MUST HAVE suitable flame arresting features to prevent a backfire from propagating into the crankcase and EXPLODING the blowby gas. Such safety devices usually consist of an anti-backflow feature built into the metering valve and/or a flame arresting screen on the fresh air inlet if there is a chance that flow could reverse.
Duke
[Modified by SWCDuke, 3:50 PM 3/16/2004]
