I did the popular "ford/Lincoln mark-8" E-fan in my truck......... mixed results....
Good: it fit into the stock fan shroud. it cooled the engine VERY well, didn't even need to run it on the higher amp/speed wire. it was quiet. it freed up noticeable HP, MPG, and throttle response =)
Bad: it seized up and I had to throw it away.... it did give warning by screeching loudly, but... the mechanical one never failed....
so now im torn between something that functions SUPER dependable, but costs me some power... or.. something that could leave me stranded and overall, free up power.....
id say buy a light weight fan to replace the stock metal one.... I've even heard of electric fans shattering if you hit water hard/deep enough... also bad