What is the smallest radius for the EM-1??
Did you read the directions, it may be there but at a guess, 22 inches. It won't look good on toy train curves of even 22 inches, let alone anything less.
I don't know why people want to run the biggest locomotive they can on a 4 by 8 layout. Running a 2-8-0 or small is far better. They look better, they run better. Two betters makes a much better.
I have have run mine on 22"R and 24R" with no issues so far. Be aware that the shape of the draw bar is critical to prevent derailments on these radii. the overhang (cab) is a bit wide. But, the loco will pull these radii.
Regards,
Jonathan