The Deltic engine is a type of high-speed diesel engine known for its unique design and efficiency. Developed in the 1950s by Napier & Son, it features a distinctive triangular arrangement of cylinders, which allows for a compact and lightweight structure. This design enables the engine to produce a high power output while maintaining fuel efficiency, making it suitable for various applications, including locomotives and marine vessels. One of the most famous uses of the Deltic engine was in the British Railways' Class 55 locomotives, which were known for their speed and performance. The engine's innovative design contributed to its reputation for reliability and power, influencing future diesel engine developments in the transportation industry.