Feed The Beast Wiki
Minecraft Joules

Minecraft Joules (MJ) are a type of energy unit introduced in BuildCraft. It is used to power BuildCraft machines as well as those from other mods (including Forestry and Railcraft).

Producing MJ

MJ are typically produced (as it is in BuildCraft and Railcraft) with Engines. Each Engine will produce a different amount of MJ and will require any variety of fuel and cooling sources if applicable. Some engines will explode if not provided with adequate cooling.

BuildCraft Engines

BuildCraft Engines are listed below. It can take a little while for these engines to warm up and produce their full output power.

Engine Production (MJ/t) Description

Redstone Engine
0.01MJ/t - 0.05MJ/t Requires a Redstone Signal to run.

Stirling Engine
1 MJ/t Requires fuel in the form of Saplings, Coal, Wood or Lava and a Redstone Signal to run. If this engine isn't powering anything while it is running, when it reaches 1000MJ it will explode.

Combustion Engine
1MJ/t - 6MJ/t Requires either Lava, Oil, Biofuel or Fuel as the fuel type, Water for cooling and a Redstone Signal to run. The engine will output different amounts of MJ based on the fuel type used. If not kept cool with water the engine will explode. Coolant can be used as well.

Forestry Engines

Engine MJ/t Description

Clockwork Engine
0.5MJ/t - 1.5MJ/t Requires the player to wind the engine. Stop when the engine turns red otherwise it will damage the player. Gradually reduces output as the engine unwinds.

Peat-fired Engine
1MJ/t - 2MJ/t Requires fuel in the form of Peat or Bituminous Peat with the latter producing the engines full output power when used.

Electrical Engine
2MJ/t This engine allows EU to be input and the engine will convert it to MJ.

Biogas Engine
1MJ/t - 5MJ/t This engine requires starting using Lava. Once it is up and running it may continue to use Lava depending upon which fuel type is used. Using Water and Milk as fuel will constantly use Lava. Using Liquid Honey, Seed Oil or Biomass only requires lava to start the engine.

Railcraft Engines

Engine MJ/t Description

Hobbyist's Steam Engine
1.6MJ/t - 2MJ/t Requires a redstone signal and Steam to operate

Commercial Steam Engine
4MJ/t Requires a redstone signal and Steam to operate

Industrial Steam Engine
8MJ/t Requires a redstone signal and Steam to operate. Requires something to output to, otherwise will explode.

Transporting MJ

In order to make use of MJ, the player will need to transport it where it is needed. Each mod has its own MJ transport system.

BuildCraft Kinesis Pipes

BuildCraft uses Kinesis Pipes to transport MJ. Each pipe type can transport only a certain amount. Only Wooden Kinesis Pipes can extract MJ from an Engine; after that other types of Kinesis Pipes will be required.