Rift Engines are powerful, magical artifacts in Skylanders: SuperChargers. The SuperChargers notably stand on elemental Rift Engines in their toy forms and use them to power their vehicles, and a silver Rift Engine is embedded in the front of the new Portal of Power; their most significant ability is to create Rifts to other worlds.
In the past, before the existence of Portals, the Rift Engines were created by the benevolent Ancients to explore countless worlds of the universe in order for them to spread the light and magic of Skylands. The use of the Engines created networks that helped link other worlds to Skylands; however, during their haste, the Ancients created the Dark Rift Engine and inadvertantly released The Darkness, who proceeded to wreck havoc across Skylands with legions of evil.
During Rift into Overdrive, many more elemental Rift Engines were rediscovered, and used by the then-growing team of SuperChargers in their vehicles to outrun Rifts. In the prequel comic, more were discovered in the Whirlpool of Destiny, and when they came in contact with the nearby Skylanders, the engines analyzed their elemental signatures and evolved them into SuperChargers; however, as stated by Gill Grunt, not only do the Skylanders have to choose one, they also have to hope it chooses them in return.