Cooling issue on highway

Every modern car including the 6.4 Mopars have run nothing but electric fans for more than 30 years. Millions on the road with no problems.
Problems always start when homegrown engineers think they know more than the companies that have invested millions of dollars in engineering and testing the systems. They have to warranty the drivelines for up o 100,000 miles so they have a vested intertest in there being minimal problems.
Factory stuff works, why always trying to reinvent the wheel...

Exactly, G3 Hemis weren't designed to run with mechanical fans except in trucks and those fans are gigantic. Just like our old carbed engines weren't designed to run with electric fans. It takes some work and know-how to get that stuff right, thermal management is no joke.