Come on, you don't really hate to tell me what I already know about it being a Ford Racing part.........

Its one thing Dave actually got right in his write up.

I'm wasn't saying that it wouldn't work, only that its not as efficient as the standard rotation. The pump is a centrifugal design with a volute chamber (like a turbo) with the offtake in the direction of rotation. A simple centrifugal pump simply has an anular space and an offtake perpendicular to the driveshaft so the coolant turns up to 90 degrees to exit. With this impeller and reversed rotation it has to effectively turn 180 to exit the pump casing on its way to the block.

As I say, it doesn't mean it doesn't work, its just not as efficient on a pump that can be marginal anyway on some installations. Ever seen one that's suffered from cavitation? Its not nice.

Martin