The Advanced Engine is an intermediary product used exclusively as part of the production chain to craft AI Robots. While they can be sold directly, they are not very profitable in comparison to the production chain required.
Assembly Line 1[]
Advanced Engines (along with Batteries) are used to craft Electric Engines. They are made from 50 Engines and 50 Circuits. Despite requiring a substantial quantity of resources and a large production line, their sale price is quite low at $70k. As they require 300 raw materials to craft, this makes their profit per raw $228.33.
On a scale from lowest to highest profit per raw, all 19 less profitable items require 9 or fewer raw materials to craft, which is significantly less resource intensive. An entire floor dedicated to Plates would be more profitable than crafting Advanced Engines for sale.
Assembly Line 2[]
Advanced Engines in AL2 require far fewer resources than in AL1, though they are close in theme as they require both Engines and Circuits. Their only use remains to construct Electric Engines. While they are more profitable than their AL1 counterparts, they still aren't ideal for direct sale compared to products on the AI Robot Head side of the technology tree.
The recipes for Advanced Engines are the same across both mobile and desktop, though they are still more expensive in desktop as their components cost more to make.