It's usually a bunch of crap. The limiting factor is the rate of convection (related to air speed over the fins). Moving the hot fluid to the fins faster, then back away from it faster won't do anything if the convection rate isn't optimized equally. It does pull the hotter fluid away from the motor faster, that's all. Once the entire system is hot I doubt it does much. Probably just works a lot better than a worn out stock water pump..