What is the most efficient 4-stroke engine?
Wärtsilä 31 – the world’s most efficient 4-stroke engine. The Wärtsilä 31 is an efficient medium-speed 4-stroke marine engine that provides the best fuel economy of any engine in its class. It is available in cylinder configurations from 8 to 16 and with a power output ranging from 4. MW at 720 and 750 rpm. Modern V24 engines have limited applications, one of which is the marine industry, where it is used for boats, like Detroit Diesel 24V-71, with its 1,550 horsepower output. Another is the Jenbacher J624 engine, which produces 4,459 kilowatts from its 4,400 horsepower rating.