Electric Engines are one of the primary components of the AI Robot Body in both Assembly Line games.
Assembly Line 1[]
Electric Engines are combined with Electric Generators and 400 Aluminum to craft AI Robot Bodies. While Electric Engines may seem better to sell than Electric Generators before AI Robots can be made, this is not the case. Electric Engines sell for $900k but require 3200 raw materials, putting their profit per raw at $276.25 each, which is quite low considering it's complex production chain and the fact that Plates sell for $245 per raw. Electric Generators sell for just under half ($470k) but use less than a quarter of the materials (640 raw) and are therefor far more profitable.
Electric Engines require 10 Engines and 40 Batteries to craft.
Assembly Line 2[]
Electric Engines are one of 4 components of the AI Robot (along with Solar Panels, AI Robot Arms, and Electric Boards). They are fairly straight forward to produce. Besides 2 Advanced Engines, their components can all be made in Crafter MK1 and below. In general, products on the path to AI Robot Heads are more profitable. Producing Electric Engines as an end product is not commonly advised.