Why are these engines over heating?

[teser]

So I'm trying to figure out why my engines are building up energy inside them leading to over heating. Right now i'm using 2 Magmatic Engines and 2 Redstone Engines to power this pump (totaling 10mj/t) which is exactly what I was told is needed to fully power a pump. I also have an autarchic gate set to both emit a redstone signal and energy pulse when there's room in the tank, therefore the engines should shut off as soon as the tank is full. Here are some screenshots.

 

[LightKnight]

Use redstone energy conduits , because those engines adjust themselvs when they are connected into a REC they can be powered forever and not overheat because the engine will run at the speed of the loss rate of the conduit and not store any extra MJ in them , they are going to use only a tiny bit of lava.

 

[teser]

good idea, thanks

 

[Omicron]

The reason this happens is because of how Buildcraft-style engines work.

Industrialcraft generators for example output energy every tick. If something is rated for 10 EU/t, it will output 10 EU, every tick, 20 times a second. Buildcraft style engines however do not output every tick. An engine rated for 4 MJ/t, like the magmatic engine, will produce 4 MJ every tick, 20 times a second, and store it in an internal buffer. Then, everytime the piston animation of the engine hits to forwardmost point, the engine will output a single burst of energy. It will output as much as it can, trying to dump its entire internal buffer in a single tick (unless the engine's maximum burst output rating is capping it).

Unfortunately, most machines that accept Buildcraft power also have a maximum input per tick. For the Buildcraft pump, that's 10 MJ. So while you are correct that supplying 10 MJ/t to the pump is the maximum that it can take, you have the issue that the engines aren't outputting energy every tick. Let's say the magmatic engine strokes twice per second (I do not actually know how fast it is, so I'm just making up a number here). That means it will spend 10 ticks generating 4 MJ/t, for a total of 40 MJ, which it will then try to dump all in a single tick. But the Buildcraft pump can only accept 10 MJ at once. So 30 of the 40 MJ remain in the magmatic engine, and this happens every stroke. It all builds up there until the engine overheats.

If you use conductive pipes or conduits, however, the magmatic engine can dump all of its energy just fine, because the pipes/conduits buffer the burst. The pump will then "catch up" by consuming the buffered energy over the next couple of ticks.

Note that you also made a mistake in your build, by the way. Redstone engines do not generate 1 MJ/t, they generate 1 MJ/s - in other words, 0.05 MJ/t. If you want to supply 10 MJ/t, you'll need to use a different engine type. But honestly, 8 MJ/t from two magmatic engines is plenty if you actually use all the energy by employing conduits. You will be getting 15.2 buckets of lava per second. And in 1.5.1, TE's own engines will no longer incur loss when outputting into conduits, which means you'll be getting the full 16 buckets per second. I highly doubt that you consume anywhere near that much lava - for example, it is enough to keep 800 geothermal generators running without interruption.