Generally for all
There are some factors that are more important to gas flow than this
Sorry Ian, I don't follow
Gas flow is very important and as such so is scavenging, its a fundimental part of how a performance engine works, thats not just the world accoring to Skiddy, thats a fact.
Lose scavenging and you have a polluted chamber prior to filling, polluted part burnt mix and fresh mix = loss in power.
As the piston come down, it has "resistance" to the air below it
One could counter "no it doesnt as its balanced out by the others going up, which are in turn are hindered by the compression cycle, which in turn are balanced out by the combustion cycle"....so on and so forth
By removing the "resistance" by creating a vacuum, piston ring better seal
you could argue that you could make ring seal worse by dragging combustion gases past them with your "Vacuum"
You could also argue that a crank case vacuum will induce a drag on an upward bound piston.
On a well built engine with a clean mesh (at the back of the crank vent), well machined and honed bores, quality rings and a good builder you will see few emisssions from the vent anyway, with regards to race regs, the reason its sometimes fed to a catch tank is that under certain conditions (such as an engine blow out) you can get a smog of oil pouring out and race officials dont want that all over their nice clean track, or indeed catching fire......be interesting to see that go through your exhaust system
On your photos it looks like your system is connected to the number six exhaust primary
Its worth mentioning that the L series isnt a closed crankcase system, the crank case and rocker cover are" connected" by the front cover and the rear oil way so any pressure differential applied to the sump will apply to the rocker cover cavity and where's your rocker cover vent connected to ???
Please don't take this as negative
I really want to understand this and on a big power V8, with and external vaccuum source there is some logic but more to do with reducing the turbulane than anything else much like a crank scraper does but were talking many hundred HP race engines here that have a very different layout so you can't automatically apply the same logic.