Ah.. the heat mechanics... one of most poorly understood and mysterious mechanics that only few can truly say they get it
Size of powerplant, affects total amount of MJ wich ship can run.
More MW is used, more "resting" heat is (since MW usages = heat), but that is ultimately affected by none other than heat efficent stat - wich affects resting stats, well as speed of heat disspation. This is most important viable to consider, if heat is concern.
Heat from distro, only affects weapons. There is weapon heat penalty mechanic, wich is universal for all ships, wich is relative to total procentage of WEP capacitor.
Smaller sized PD's, due of less overall MW in WEP capacitor, reaches those penalty faster, so they "feel" hotter to use, due of said mechanic.
It works as follows:
When WEP distro is bellow 75%(7 bars and bellow), it starts adds "extra" heat to weapons, linearly. Caps out at 25% of WEP, and at that point, the heat gained, from firing an weapon, even if there is enough of WEP juice to fire said weapon, the heat from such is
doubled to what is being listed on used weapon heat.
This is why firing some weapons, when WEP capacitor is not full, causes extra heat bulidup.
For Corsair, most of its heat issues comes from low heat capacity, but it does have better than average heat disspation. As for weapons heat, LE powerplant is best bet to tackle on heat.... it does make big diffrence.
When used on my Corsair, Armoured plant with monstered, wich has efficent stat at 0.35... ship was running quite hot, I could not fire my 5x rails(60 heat/salvo) more than twice, and not overheat. So I had about 120 units of heat to work with.
But when I used LE, grade 3, with efficent stat of 0.22... Now I can fire my 5x rails, 3 times, and heat disspation is notable faster. My ROF, went up almost double time.
Not only because I had more heat capacity to work with (about 30-40 heat units more), but also because it cools down faster, much faster.