it not hard to cool 500hp they never make 500 at idle i used both but still like the belt they work if the belt is on the pulley .if the electric fans die you may have more work and money to get back running .low speed may not be to bad with a open engine bay i sold a bbc 548 soild roller 14.8 cr that did make 700+hp EZ in 28 ford with a very small alum rad and one big electric fan never ran hot at idle and was driven on the street i had the same engine in my gto that did run a bit hot so alot has to do with air getting in and out of the engine bay water speed running thru the rad has alot to do with keeping something cool so do not over look it