clutch fan

clutch fans slip and turn at as low as 80% of crank speed at idle and lo speeds...exactly where most engines need extra air.Try a proper mechanical fan but i'm betting it needs a 3 row or the newer 1 1/4" dual tube style rad.
A directly mounted fan to the W/P?
HP thief in a big way.
Better radiator? Probably so with the B.B.