Fuel & Fuel Sources
The engine system has two completely separate fuel systems — the fluid combustion chamber uses pure datapack fuel, the steam power chamber uses pure vanilla fuel. They never mix.
| Fluid engine (combustion chamber) | Steam engine (power chamber) | |
|---|---|---|
| Fuel source | Datapack engine_fuel/*.json |
Pure vanilla — bucket items' furnace burn time + solid items' burnTime |
| How to add fuel | Write a datapack JSON, /reload |
Use vanilla furnace fuel rules (lava buckets, coal, etc.) |
| Source storage | Any fluid tank with the fluid (e.g. Quick-Fill Fluid Tank) | Water tank + fluid fuel tank and/or Quick-Fill Fuel Vault (solid) |
Fluid combustion chamber fuel (datapack)
Fluid chamber fuels live in data/<namespace>/engine_fuel/*.json and are hot-reloaded with /reload:
| Field | Meaning |
|---|---|
fluid |
Fluid id to burn |
consumption |
mb/s per chamber (default 1.0) |
heat |
Heat multiplier for the temperature model |
stress |
Stress multiplier on the 8192 SU base |
- No priority field — when several fuels are usable, the controller picks the first one in source scan order (the order the engine scans neighbouring tanks). Old datapacks with a
priorityfield are ignored. - No temperature fields — overheat (220°C), overcooling (100°C) and the economy target (155°C) are fixed engine constants.
- One fuel at a time per engine (single-fuel rule, chosen by source scan order, never mixed).
Steam engine fuel (pure vanilla)
No datapack needed — vanilla furnace rules apply:
- Fluid fuel: any bucket item with a vanilla furnace burn time > 0 (e.g. lava bucket = 20000 ticks). Add fuel the vanilla way (set the bucket item's furnace burn time — the engine shares the same fuel registry as the furnace).
- Solid fuel: any item with vanilla
burnTime > 0(coal = 1600 ticks, etc.), stored in a Quick-Fill Fuel Vault near the engine, auto-drawn by the controller. - Fluid fuel is preferred; solid fuel is only drawn when no fluid fuel is available.
Quick-Fill Fluid Tank

The Quick-Fill Fluid Tank (ccpe:quick_fill_fluid_tank) is a 6-sided attachable block with 4000 mb single-slot fluid storage:
- Right-click with a fluid container to pour the fluid into the tank.
- Right-click with an empty bucket to fill one bucket from the tank.
- Goggle tooltip like Create's fluid tank.
- Exposes a fluid capability, so the engine drains water / fluid fuel directly from it.
Quick-Fill Fuel Vault

The Quick-Fill Fuel Vault (ccpe:quick_fill_fuel_vault) is a 6-sided attachable step block with a single-item-type inventory (capacity 1024 = 16 stacks × 64), no GUI:
- Right-click with an item to store the whole stack (the vault accepts only one item type total).
- Sneak + right-click empty-handed to take out one stack (the item's max stack size, or all if fewer remain).
- A successful deposit/withdraw plays an open-lid animation (auto-closes after a short time).
- Breaking the block drops its contents.
- Exposes an item capability, so the steam engine draws solid fuel from it automatically (parallel burning,
N×Kper batch, switching vaults when one runs low).
Batch refills (how the engine draws)
The engine has zero internal fluid cache — it draws into a small reserve from source storages via capability on each batch refill:
- Batch size = chamber count × K, where K is the configurable batch multiplier (
engineSourceBatchMultiplier, default 1.0, range 0.25–64; cached once when entering a world). - The engine draws from the head of its source list; if the head tank/vault is empty, removed or holds the wrong content, it immediately advances to the next source (same tick, zero downtime).
- The reserve is refilled the same tick it runs out, so the stress network never flickers.