Quoted from Enchantress:Vic, what is an optimal maintained flipper temp before power is diminished? What temp is maintained with your Tibetan breeze? Do you see that these test results are similar in all Stern's being that they generally use same/similar coils? Or like you noted with ramp height/length, the entire play field layout truly effects temps as well. You're really taking this to a whole other scientific level!!
You want to keep the flippers under 130F (I forgot to but an "onset of fade" line on the graph to show this...). The Tibetan Breeze kit keeps temps around 110F-120F, sometimes a bit lower. Basically it takes care of any fade/mushiness no matter how long you play or what your play style is. The chart on the product page lists the kind of coils in Elvira (and all the other pins listed) and the uncooled stock flipper temps, plus how long they were tested straight.
There are a lot of variables that affect coil heat. Software modes, number of multiballs, short/open playfield, etc. Play style will most affect how fast your temps go up and how high they get, although on Sterns it's much better for trap players (than JJP, Spooky, CGC, etc) because hold temps are stable due to their ultra fast microsecond duty cycles no one else has (everyone else is limited to 1ms duty cycles, minimum). So for a Stern really only a defensive flip player (flipping when the ball isn't close in anticipation of what the ball might do) will raise the naked coil temps faster/higher, otherwise it will be a slower more linear progression to 140-150F range and pretty much stay there.