According to the University of Southern California (USC), as of 2010 the Wartsila-Sulzer RTA96-C two-stroke diesel engine is the world's largest engine. It has 14 cylinders, and weighs 2,300 tons. Its horsepower rating is 108,920 maximum horsepower at 102 revolutions per minute. According to USC, the engine is used to drive large container ships. It is so large a person can stand inside the crankcase. Its thermal efficiency is 52 percent, which is quite good for an engine.
The Queen Mary II is powered by four Wartsila 16V46C engines along with General Electric Turbines. Each Wartsila engine weighs 210 tons, and measures about 15 yards long and about 3 yards wide. The bore is about 18 inches, and the stroke is 23 inches. Each engine produces 16.8 megawatts of power, and spin at 514 RPM. According to Cyber Cruises, the 16V46C is an environmentally friendly design, which reduces exhaust pollution significantly from older style engines.
The Weichai CW16V is a V-16 engine. It produces 2,394 horsepower at 1000 RPM. It has a bore of 8 inches, and a stroke of about 10 inches. It has an 86 liter displacement. It is turbocharged, and intercooled. While this is nowhere near as large as the Wartsila engines, it has a very high horsepower-to-displacement ratio. Dividing 2,394 by 86 yields 28 horsepower per liter of power.