BattleMechs require a constant supply of power for movement and combat. Located near the center torso area, a BattleMech's fusion plant is well protected, but it still can sustain damage in battle sufficient enough to cause it to overload, destroying the'mech and potentially killing the pilot.

The larger the enigne, the more powerful the 'mech is and the faster it runs. Enignes can be repaired and swapped in the 'Mech Lab. Engines come in the standard form or the "XL" (Extra Light) version, which weighs less, but takes up critical space in the left and right torso.