brendon_ak
Well-known member
- Joined
- Jun 7, 2011
- Location
- Hood River, OR
Isn't the engine an air pump? So if the case can vent then your vacuum on an NA engine should come from the intake side, no? Or am I not getting it?
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Yep, full exhaust.
Been thinking about the pcv. On my old domestic vehicles there was a filtered air intake routed to one valve cover and an “exhaust” (pcv) on the other. On the Volvo we exhaust the crankcase through the flametrap, but is there a crankcase “intake?” Or, assuming zero blow by, would it draw a vacuum on the sealed crankcase?
Isn't the engine an air pump? So if the case can vent then your vacuum on an NA engine should come from the intake side, no? Or am I not getting it?
Further thoughts: does the aftermarket catch can do the same thing as the factory oil separator (flame trap box)?
I was looking at the turbo PCV system in detail while putting my '85 B21FT back together. The "flame trap" or "flame arrestor" is the mesh screen that prevents fire (e.g. intake manifold backfire) from getting into the block. On high proof alcohol (everclear, 151 rum) there's a flame trap on the opening to prevent accidents:
In the non-turbo setups, the flame trap is a plastic mesh within the PCV lines. In the turbo setups, the mesh isn't needed (not quite sure why). The vent off the oil separator gets split into a bigger line to the pre-turbo intake hose, and a smaller line to manifold vacuum. Some posts say that the manifold vacuum line isn't needed.
The breather box drains directly back into the block. The catch can gets what's left over (or could replace the breather box if the catch can drains well to the block).
Funny how steel rimpz have come back to some extent. I recall Corvette rally's being the hot ticket in school. Still a nice looking set up. Nice that the aftermarket has brought out modern sizes on the old school stuff.