Trivia Thursday: What’s the world’s largest 4-stroke, spark-ignited gas engine in the world?

It’s the 18-cylinder, 25,000-horsepower turbocharged beast from industrial manufacturer Wartsila. Designed for large power plants, the engine stretches over 61 feet long and weighs 396 tons. Not sure of the total displacement, but the cylinder bores are nearly 20 inches in diameter. Taking a cue from performance engines, the pistons have a forged-steel top, but the skirts are cast iron with hardened ring seats. There’s also a low-tension 3-ring design with two compression and a single oil ring.

According to company literature, the engine uses lean-burn technology to save fuel and reduce emissions. Taking a cue from diesels, there is a pre-chamber for the ignition. Designed primarily to run on natural gas, the engine also uses a sophisticated management system with sensors to monitor cylinder pressure in each hole and knock sensors in the block, giving the ECUs proper information to control fuel and spark timing. Wartsila also says simulation and CFD software were used in the engine’s design, and studies were as detailed as checking the turbulence around the spark plug. 

The engine is rated at 18,810 kW at 500 rpm, or 25,214 horsepower. Speed can be kicked up to 514 rpm, boosting the horsepower to 25,817. Doing the math reveals that’s equal to almost 258,000 lb-ft of torque.

Wartsila also makes a 2-stroke diesel that’s even larger at 14 cylinders and some 80,000 kW, or 107,000 horsepower!