The SD45 required a 20-cylinder 645 prime mover to crank out 3600 hp. Later, EMD stumbled with the 50 series when it tried to squeeze 3500 or 3600 hp out of a 16-cylinder 645. There were problems with premature engine wear, among other things, which caused a number of roads to derate the 50 series locomotives. But MPI's MP36 series of passenger locomotives uses, I understand, a Czech-built version of the 16-cylinder 645 rated at 3600 hp, and I haven't heard of any complaints or problems with the engines. How did they achieve this?