1100cc Cooper-JAPs regularly competed in Formula 2 races. So I suppose a reasonable description of Schell's car would be an "1100cc Formula 2 Cooper-JAP"

As Schell drove a Cooper-JAP in the Formula 3 support race, there will be pictures of this car around to confuse the issue. The Monaco organisers would not have allowed him to run the same car in both races so the car must have had an 1100cc engine.