I’m going to post 2 separate replies, one for Michael and one for Chris.
Michael this is for you.
In answer to your question about the distance from the fan to the radiator. That would be the leading edge of the fan blade nearest the radiator. When Tom and I did our cooling study, one of the things we tested for was just that. We found that the "sweet spot" was 1"-1 1/8" using our "air-buck" to do the tests (see the Tech Tips section of this Web Site). That was our test for the Sunbeam, but the fan manufactures make general across the board recommendations as well.
As for your question about the electric water pump, we didn"t test any of these, but I’m sure it would have been interesting. Most of the advantage here is in the area of conserving power I think, and not so much in the cooling itself, although sometimes results can be surprising. Andy’s Tiger is still set up to do more tests, but it would have to wait for summer’s hot temps. I don’t know if I’m up for more testing. I’ll keep it in mind for next summer.