The Cummins ARP 2000 and 625 are two different types of diesel engines, each with its own unique characteristics. The ARP 2000 is a turbocharged 6-cylinder engine that was developed in the early 1990s and has since been used in many heavy duty applications such as construction equipment, marine vessels, and over-the-road trucks. It has an impressive power output of up to 400 horsepower (hp) at 2200 rpm. On the other hand, the Cummins 625 is a non-turbocharged 4 cylinder engine that was released in 2001 and is commonly seen in agricultural machinery as well as recreational vehicles such as motor homes. Its maximum power output stands at 325 hp at 2400rpm which makes it slightly less powerful than its predecessor. Both models have similar bore/stroke ratios which result in comparable torque figures however; the main difference between them lies within their technology levels due to advancements made over time with regards to fuel delivery systems, cooling systems etc., resulting in higher efficiency ratings for newer models like the ARP 2000 compared to older ones like the Cummins 625.