Of course yes, in order for teh fan to draw air through the rad, it must be sealed tight against it.

Either the fan itself as you have it, or on a cowling/duct of some sort as per OE

I see your's is a dual pass core. Perhaps a big single pass might work better ?

And fan positioning can play a part. Mount one at any corner, and a smaller fat at the opposite corner.

Of course all car fans are quite big...but motorbike fans are quite small.

Ive a 16" puller on mine and a smaller 6" motorbike fan. That little fan really does make a difference ! Check egay for such fans