electric fans are self shrouded, but its a good idea to make a cover for the area not covered by the fan. i always just used flat sheet metal attached to the rad frame with a hole cut in the middle for the elect fan. use the biggest fan that will fit the core and cover the rest to make sure the air is drawn thru the fan and not around. also test to be sure its drawing thru the core, sucks to find out the hard way you wired it backwards...lol...not that i have ever done it...lol