Cool! The most powerful diesel in the world...
 

Check out these cylinders...
http://people.bath.ac.uk/ccsshb/12cy...6c_cyldeck.jpg

Here's more...
http://people.bath.ac.uk/ccsshb/12cyl/

I don't understand the purpose of the whole crosshead/piston rod assembly.

Also, I've never understood why automotive diesel engines don't use a two-stroke design. They are more efficient than four-stroke diesels.

Torque? (Just throwing out a guess here...I have no clue).

...and emissions.

It sez - I assume this is done so the the sideways forces produced by the connecting rod are absorbed by the crosshead and not by the piston. Those sideways forces are what makes the cylinders in an auto engine get oval-shaped over time.

The very bottom photo in the link shows the Wartsila-Sulzer 12RT-A96.
That engine was built by Aioi Works of Japan’s Diesel United, Ltd, but the banners on the wall where the 10 cylinder is being produced (next-to-last photo in that link) look Korean to me. (not that I'm any kind of expert!!)

I guess the Fins are doing their fair share of outsourcing.

Our engines are nowhere near as big. We max out around 3000 hp.

Emissions couldn't be met years ago, lots of companies tried. Now? No chance of meeting current levels.

Maybe for Tata's $2,500 car in India. Not here.

A boat I used to run had triple Maybach V-12 turbo-supercharged compound diesels. Each bank of six cylinders had a turbocharger that drove a gearbox that spun a centrifical supercharger that nestled in the 'V'.... Velocity stacks open vertically, no filtration. Sounded like the inlet of a jet engine while running.

Little over 500 tons of yacht, 33 knots top speed. 8 tons of fuel a day at that speed. Engine room was always cool while spooled up, but you had to go thru an airlock door to get in there. Was several PSI below normal pressure when at speed. Cooling air was drawn down thru the dry stack exhausts, and dried while cooling the stacks. The doors had to be closed when running. The Greek engine room crew stood all around these things, and they were almost deaf (even with earplugs and protective headgear) for a week after we made port.

Was pretty imressive. Last time I fueled that beast was for $ .66 a gallon in Panama in 1980.

Not sure about these ones, but in the 80's I rebuilt three Hamilton man8 cylinder engines that were almost as big. They use a crosshead design because there is a combustion chamber above and below the piston. They fire twice per stroke with a bore of 36" and a 24" stroke.
The three piece piston is bolted together onto a round long piston rod that bolts into the crosshead. The lower head has a packer that the piston rod goes through and keeps the combustion gasses in the chamber. The packer is basically a series of captured segmental rings that act as pressure breakdown bushings, very similar to a large reciprocating compressor.

Two strokes are notoriously inefficient and dirty as fas as emissions go. The piston sucks in the air/fuel at the same time the exhaust is going out so to ensure complete combustion chamber filling some of the intake charge goes out the exhaust, unburned.
Direct port fuel injection addresses that to a point but not all the way. 4 stroke engines are more reliable, more efficient, and cleaner.