Processing Unit to Engine Unit Chain

Lore & Background

In the sprawling industrial landscape of the alien world, the Processing Unit represents a small but critical leap in manufacturing sophistication. Where earlier components were simple combinations of metal and copper, the Processing Unit demands that a factory can simultaneously smelt, refine, and chemically synthesize. It is the first component that forces a player to think in terms of multi-stage pipelines rather than single-machine recipes. The Engine Unit, built atop the Processing Unit, carries a heavier symbolic weight. It is the mechanical heart of the Electric Locomotive, the machine that transforms a static factory into a mobile, interconnected network of production nodes. Without Engine Units, trains do not run; without trains, the factory is capped at whatever its immediate surroundings can supply. The chain thus represents the moment a player's operation shifts from a single-site workshop to a true industrial empire. Fans often recall the first time they successfully produced an Engine Unit as a small, quiet triumph. The assembly machine clicks, a small metallic unit slides out, and the factory feels, for the first time, like it is building toward something larger than itself. It is not the grandest component in the game, but it is the one that changes the shape of the map.

In Their Own Story

The night shift at Sector 7 was supposed to be routine. Kael watched the conveyor belts pulse with their steady rhythm—Iron Plates sliding into the Smelter, Copper Ore feeding the second line, the Oil Refinery belching its low, constant breath of heat into the humid air. The Chemical Plant sat between them, its pipes a tangle of yellow and grey, converting Petroleum and Water into the glossy Plastic Bars that would become the soul of every Processing Unit. He had tripled the Smelter output last week. The Steel was piling up in the buffer, a neat little mountain of grey rectangles. The Plastic Bars, though, were still trickling. One Chemical Plant. One Oil Refinery. The ratio was 1:2, and he had only one of each feeding the Assembly Machine. The Processing Units sat in the output slot, waiting, while the second input line for Steel idled empty. Kael pulled up the schematic, traced the flow with a grease-stained finger, and made a decision. Two more Smelters. A second Chemical Plant. A second Oil Refinery. He routed the pipes, placed the machines, and watched the belts finally sync. The first Engine Unit slid out of the Assembly Machine with a soft metallic clink. He picked it up, turned it over in his palm, and felt the weight of it—dense, solid, ready to be dropped into a locomotive and set rolling across the dark, waiting landscape.

Reader's Guide

The chain has two assembly steps. First, the Processing Unit: 1 Electronic Circuit + 2 Plastic Bars → 1 Processing Unit in an Assembly Machine. Second, the Engine Unit: 1 Processing Unit + 2 Steel → 1 Engine Unit in an Assembly Machine. Upstream dependencies: Electronic Circuit requires 1 Iron Plate + 1 Copper Plate (Assembly Machine). Plastic Bar requires 1 Petroleum + 1 Water (Chemical Plant), and Petroleum requires 1 Crude Oil (Oil Refinery). Steel requires 1 Iron Ore (Smelter). Iron Plate and Copper Plate each require 1 unit of their respective ore (Smelter). The optimal ratio for 1 Engine Unit is: 3 Iron Ore, 1 Copper Ore, 2 Crude Oil, 2 Water. The 1 PU : 2 Steel ratio at the final step is the most commonly miscalculated link. Expect to produce exactly twice as much Steel as Processing Units. The bottleneck is almost always the Plastic Bar pipeline. It is the longest chain in the system—Crude Oil → Petroleum → Plastic Bar—spanning three distinct machine types. Steel, by contrast, is a single Smelter step. In early-to-mid game, the Oil Refinery and Chemical Plant throughput will limit your EU output long before your Smelters do. As the factory scales, this chain feeds two major downstream consumers: the Electric Locomotive (5 Steel + 5 Engine Units) and the Rocket Part (10 Engine Units + 10 Electronic Circuits + 10 Plastic Bars). Processing Units also feed Advanced Circuits, so PU production serves dual purposes and should be over-produced slightly to avoid starving either line.

Did You Know?

• The Plastic Bar sub-chain (Crude Oil → Petroleum → Plastic Bar) spans three different machine types, making it the longest upstream dependency in the entire Engine Unit recipe tree.
• Processing Units are a shared input for both Engine Units and Advanced Circuits, meaning a single PU production line can serve two separate downstream consumers simultaneously.
• The 1:2 ratio of Processing Units to Steel in the Engine Unit recipe is the most frequently miscalculated ratio in the chain, often leading to one of the two inputs idling in the Assembly Machine.
• Engine Units are a required component for the Electric Locomotive, making this chain a hard prerequisite for any rail-based logistics network in the game.