The Jet Engine is a pair of red rocket engines that can be equipped on the feet of Dr. Eggman's Egg Walker. Once obtained, it allows the Egg Walker to use Hover, enabling it to hover across gaps. It is the equivalent to Tails' Booster.
The Jet Engine is located in Lost Colony. After passing the first Star Post, the player will enter a room that is completely covered in darkness, but can be illuminated by destroying enemies. The Jet Engine can then be found on the upper level in the room, which is found around the left corner upon entering the room. To get to this level the player can simply climb up the nearby Containers.