As stated. Engine rating divided by 25 (rounded down) up to a max of 10, then you are given slots on the engine to let you equip more.
Standard have a heat of 1 while double is 1.4 but takes up 3 slots instead of a standard's one slot. This is a fact that has no impact on the number of heat sinks that come with an engine nor does it have an impact on the number of engine slots used up by ones that you add to it. One engine slot is used per heat sink regardless if double or not.
From my understanding, mechs start with a heat rating of 30 + 10 needed for having an engine + any extra. Standard heat sinks also have a -.1 heat/sec value and double have a -.14 heat/sec value.
Weapons generate heat when fired. An example being the medium laser at 4 heat when fired. If you only have the base 30 and 10 Standard for the engine, this will register as 10% heat generated assuming a base of 0% (map dependent).
This next part I'm not sure of. I don't know if the 30 heat rating is just a static heat rating. If so then....
With 10 standard heat sinks, the rate of dissipation would be -1 heat / second so it would take 4 seconds for that 10% to drop down to 0% again.
On my Cat, I have the std 315 and double heat sinks. So I have the 10 from the engine plus 2 slots. I also have a heat sink in each side torso for a total of 14 dbl hs. 16.8 + 30 = 46.8 rating with -1.96 heat per second.
Now I forgot to factor something in. The heat generated by the laser is generated over it's shot duration. If it is 2 seconds then that is only 2 heat per second generated and so I don't even see the heat register for just one med laser (I've tested this in game). If I fire two, however, I will see heat generated. The two will generated 4 heat per second over 2 seconds (total of 8 heat) but I dissipate 2 heat per second so I get only 2 heat per second generated over the two seconds for a total of 4 heat. This works out to be about 8.5% heat generated from 0% and is reduced back down to 0% in two seconds. This is pretty much spot on so I would have to concur that the +30 heat rating is just a static heat rating that all mechs have. It's not impacted by the dbl hs upgrade in anyway.
Edited by Deamhan, 22 January 2013 - 02:57 PM.