Just read something in the current Diesel Era magazine I was not aware of. EMD, in their new SD70ACe-T4 locomotives, meeting the new Tier-4 standards, has abandoned their long time 2-cycle power plant standard (since the late 1930's - the 567, 645, 710, etc) in favor of a new 4-cycle design. Everybody else of significance uses 4-cycle power today. The new engine, known as the 12-1010J (1010 cubic inches per cylinder, wow!), a V-12, produces 4,600 HP of fuel efficient power. The new 1010J features a two-stage turbo system, consisting of three (yes, three!) turbochargers, one for primary high pressure output, and two for secondary low pressure output. This provides better power output over the engine's RPM range. Results - better fuel efficiency and lower emissions. Just what the EPA doctor ordered I guess! There is an EGR exhaust control system that also allows lower emissions. Folks - locomotives are no longer relatively simple machines! Ken ps - I cannot imagine the thought of EMD units chugging up a hill like the GE FDL units do/did!