First of all, their are many types of engines in the world. However, this article briefly highlights the largest diesel engine in the world 2019-2020. The photo shows Wärtsilä-Sulzer RTA96-C – the largest diesel engine in the world. It is also the largest reciprocating engine, or piston engine, in the world (the common kind that is in cars etc.).
Furthermore, Wärtsilä-Sulzer RTA96-C is used to propel some of the largest container ships in the world. The biggest version is 13.5 m (44 ft) tall, 26.6 m (87 ft) wide, weighs 2,300 tonnes, has 14 cylinders and an effect of 108,920 hp.
You might wonder what kind of behemoth would need so much power. In 2006, the Wärtsilä RT-flex96C engine was installed and set sail on the Emma Mærsk. Emma is a cargo ship that can carry 11,000 20-foot shipping containers at a breakneck speed of 31 knots, whereas most other ships in its class typically cruise with 20 knots.