Actually modern cars do have completely sealed systems with no fresh air
introduced into the system.
On the cars I service there may or may not be a valve, but in either case
there are two hoses from the crankcase. A small hose going to manifold
vacuum, and a larger hose going to the inlet upstream of the throttle plate.
the dipstick has an o-ring to seal it, and the oil cap is sealed.
At idle, the small vac hose pulls a small vacuum in the crankcase. Not
enough vacuum is pulled to draw air in past the crank/cam seals. At high
load, the blow by is sucked out the large hose.
Simple and works great. How it would adapt to a LBC I am not sure.
Rick
On Wed, Mar 17, 2010 at 2:00 PM, Bob Spidell <bspidell@comcast.net> wrote:
> Hi Michael,
>
> If you mean the non-vented approach pulls more vacuum on the crankcase I
> agree. But, you're pulling unfiltered air in through other gaps (like around
> the crankcase seal).
>
> The 'sealed' PCV system works good on our cars, but it's not a PCV 'system'
> per se. A proper PCV system circulates filtered air through the crankcase,
> mixes it with blowby and sends it back through the intake manifold.
>
>
> bs
>
> --------------------------------
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