Electric - Pusher Fan ?

I'm currently running a stock, 6 blade, mechanical fan. On a hot day, in certain conditions, My, near stock, 318 gets, a little hot (210+). -- On the highway, it runs 190-195. -- If I install a electric, pusher, fan, will it block air, and impact the temperature, while it's off, on the highway ?

Some, but probably not enough to make much of a difference.
The only way to know for sure is to try it.