JB Comp:

If you do a little searching on Google, you should probably be able to find info on past four stroke conversions in cars. Just off the top of my head, from memory, there have been numerous T-Maxx trucks that have run OS four stroke engines. The OS26 four stroke was a factory mod to be used in Kyosho Super Ten cars and it used a cooling fan.

There is a fellow here on RCU who stuffed a Saito twin cylinder engine into his CEN monster truck. He also used a cooling fan.

The video you linked too, is an OS 120 supercharged four stroke. A monster sized engine stuffed into that truggy.

In Europe, it is wildly popular to put huge four stroke engines into sled pulling trucks. "Micropullers" they call them. (Well, two strokes also).