[ Thanks to Jerry Howell for the following wonderful information! ]

Now this is an engine!

The Wartsila NSD (Sulzer) RTA96-C two-stroke diesel engine
is the most powerful and most efficient piston prime-mover in the world today.

Bore - just under 3'2" (965mm). Stroke - just over 8'2" (2489mm). Available in 6 through 12 cylinder versions (all inline). Engine weight exceeds 2000 tons in the 12 cylinder version (the crankshaft alone exceeds 300 tons). Point of maximum continuous power is 89,640 HP (66,844kW) at 100RPM with the 12 cylinder version. Point of maximum fuel economy is 53,244 HP(37,704kW)at 90 RPM.

The 12-cylinder engine exceeded 100,000 horsepower during overspeed testing (all of 101.5 RPM!) while under test at Japan's Diesel Union works (who built the first engines and from whmo these pictures are taken). Fuel consumption at maximum power is 0.278 lbs/HP/hour (BSFC). Fuel consumption at maximum economy is 0.260 lbs/HP/hour. At maximum economy the Sulzer engine exceeds 50% thermal efficiency: i.e. more than 50% of the fuel going into the engine is converted to power. For comparison, consider that automotive and small aircraft spark-ignition engines have British Standard Fuel Consumption figures in the 0.40-0.60 lbs/HP/hour range and 25-30% thermal efficiency. Even at its most efficient power setting, the Sulzer 12 cylinder consumes nearly 1,660 gallons of heavy fuel oil an hour.

These engines are being used in ships. More information (in PDF format) is available here:
14 cylinders and more cylinder power for the Sulzer RTA96C
6,690 TEU type Container Ship P&O NED LLOYD SOUTHAMPTON

10 cylinder engine crankshaft being installed

10 cylinder engine cylinders being installed

The 12 cylinder engine