The Combustion Engine is the third tier of engine. They use iron instead of wood or cobblestone, making them the most expensive engine, but Combustion Engines are also the most powerful engine type that requires a certain fuel. They run the fastest and do the most per stroke. They draw full stacks when used on a Wooden Pipe and move quarries without delays between each action.
Combustion Engines can waste oil or fuel if it is added when the engine is already full, so taking the time to create an "add on demand" system that supplies oil only when you flick a lever, can save a lot of oil. The downside is that you need to keep a close eye on the engines as they use the oil fairly quickly. It may also be possible to set up a Redstone repeater system to send out oil at the same rate the engines use it. Fuel lasts about 40 times as long as regular oil does in a combustion engine.
The engine also produces heat and needs a steady supply of water to the engine, or else it will explode. A single water Pump working at full speed can keep 3 combustion engines running 24/7 without fear of any of them exploding.Alternatively, the player can set up 'Dry-Cooling' Combustion Engines by connecting them to a 4/5 Redstone Repeater Clock, which intermittently shuts down the Combustion Engine(s) to cool, and then restarts a moment later. This eliminates the need for costly and space-consuming pumping equipment and plumbing, and reduces the hazards presented by laggy pipes.
A Combustion Engine's output is also dependent on its fuel. For example, it would take four combustion engines running on crude Oil to power a Refinery at maximum efficiency, but only two engines if they're burning Fuel instead. This may be the cause of some inadvertent explosions, as players put 4 Combustion Engines in place to power a machine at first, only to fill them with fuel at a later date.
Video Tutorial Edit