Running without a thermostat ok?

worked for a major truck researce lab this is what we found the shroud is very inporant why the fan only pull air from the area in front of it with out one now the air hit the hot motor and some is forced back to the cornors of the rad. thus a heat problem with the shroud the fan pulls air across the hole rad the was found in wind tunnel test with smoke tracer beleve it or not it dose happen we also test with and with out, big differene