I can't see it acting like a true turbine and increasing crankcase pressure. For one, the crank doesn't spin fast enough to have a turbine effect. You would need some REALLY big fins to get any useful pressure difference at the crank speeds.
However, it may increase the turbulence inside the crankcase, which would be a good thing to atomize the fuel. Depending on the shape of the groves in relation to the intake ports and path, it may direct the airflow through the intake better. Just theory, I don't know for sure. I'll check it out...
Duncan Racing 340PV, +2 A-arms, +4 LSR axle, and a host of other goodies.