Been doing some digging trying to understand the issues being discussed. Ran across this, here:
https://www.enginelabs.com/tech-stories ... orsepower/
"The concept was first introduced by Bill Million at Hedman Hedders and initially developed on the engine dynos at both Edelbrock and Traco Engineering. Traco-powered Penske Trans Am Camaros were among the first cars to run it in competition.
A Pan-Evac system connects the valve covers on both sides of the engine to the exhaust header collectors with one-way check valves and vent tubes that blend into the exhaust stream at approximately 45 degrees. Exiting exhaust gasses pull a vacuum on the tubes, thus drawing excess crankcase pressure from the sump and discharging it out the collector. This action relieves blow-by pressure under the rings, reducing windage and contamination. Although purely passive, the system proved remarkably efficient, and thousands of racers used them religiously until the emergence of modern external vacuum pumps."
All of what's discussed in that write up appears to relate only to hot street engines and racing engines.
?Why wouldn't you use this sort of set up on a mild to stock engine?
I'm guessing that theoretically there is not enough crank case pressure or cylinder pressure (and potential blow by) to warrant the
"upgrade" to having vacuum on the crank case.
?Even then, why not simply use the one way valve arrangement running from the valve covers to the exhaust collector?
?Could you also plumb the same arrangment to feed into the turbo collector, and thereby have "adjustable" (by way of the accelerator pedal) vacuum on the crank case? (I know it's a simplification of the possible effects and pressure differences, but in theory, would it work?)