Some of them - especially 10/1 flavor, were simply 8/1 designs revved to 1000rpm. Not recommended! If they modified bore and stroke to achieve 12 hp at low rpm, that is a much better design. Our 18/1 units for instance are rated at 750rpm and extra hp achieved by both bore and stroke enhancements to get a lot more displacement. Personally, I have not dealt with anything described as a 12/1.
dieselgman