The surface speed on the outside of the LT500 crankshaft is about 175 feet per second at 8000 RPM.  The peak velocity of the mixture of fuel and air moving over the outside surface of the crankshaft where it enter the bottom of the transfer ports is in the range of 300 to 400 feet per second.  The actual velocity of the mixture depends upon how well the pipe and ports are working together.

The guys selling this snake oil claim that the turbo cranks blows or pushes air and fuel into the transfer openings.  Knowing the above information about the  outside speed of the crank where the grooves or paddles are located, makes it obvious that it is impossible to push or pull something that is already going twice as fast as the thing doing the pushing.  It is impossible to push or pull another vehicle that is going twice the speed of the tow vehicle.

I have seen the turbo crank fad come and go about 3 or 4 time during my career.  Early in my career I did a lot of testing on turbo cranks with a lot of different types of surfaces on the sides and OD of the crank webs.  I built one that was knurled like the handle on your ratchet.  I built ones that had shallow grooves, deep grooves, straight grooves, angled grooves, I even built one that looked like a sand tire with paddles. 

The power went down as the outside of the crank went from smooth to rough.  The "paddle crank" showed the greatest power loss.  The only advantage was the engine SEEMED to clean out a little faster after the lower end got loaded up from idling for long periods of time.