Quote:
Originally Posted by PoorMans180SX
Honestly, I'm impressed with the RB with no catch can. I edited my response above, but can you explain how you set crankcase pressure? Is there a way to do it without a restrictive air filter?
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Low pressure from venturi, vacuum pump, or air filter. The energy must overcome the blow-by gas, and the volume of the crankcase. Volume just like with intercoolers acts as a capacitor and buffers the differential of pressure as it is applied, in other words extra volume slows down and weakens the pressure signal. Keeping a crankcase volume small as possible is a key point when not using a vacuum pump or dry sump system. A venturi is more and more difficult as blow-by is increasing, you need more energy and the venturi is a pressure differential and orifice limited, you can't get "more" if you need it as the engine ages or when its cold and blow-by is much higher.
If you size a turbocharger correctly to account for the loss associated with air filter pressure drop it does not influence final power output of the engine. It doesn't matter if there is some 1.5" Hg pressure drop because that will raise pressure ratio and if you look at modern turbocharger compressor maps as the pressure ratio increases they also flow more total volumetric rate (the maps LEAN to the right as pressure ratio is increasing).