Dual E-fans & Shroud

Wired my dual spal fans through two seperate relay's. first comes on with a 190 degree sensor, the second through a simple adjustable controller with a a/c switch also. I do wish they where curved blades instead of straight blade, when both are on can be a little loud, but have never had a overheating issue, even in stop and go traffic with the a/c blowing cold in the hot south. Has anyone swapped blade on a spal unit before?