The only experience I've had with different nitro content was with my early Saito 100 and 82. With both of those engines I was able to lean engine about 1/8 turn in from where I was at with 15% Nitro. In both engines that was the case. It seemed to make engine "crisper" in all regards and of course gave considerable more power. And while I haven't used a temp gun or anything so sophisicated, the "touch test" tells me they run cooler. One thing for sure is they didn't overheat and lose power in hover. It corrected that. Also, the first thing I did when I experienced overheating was to open the cowls per above pictures. I did that when I was using 15%. It helped a lot. And things just got better with the 30%. Also, my run times increased with the 30% fuel. All my other engines, (more Saitos and some YS) I haven't ever ran the 15%. I started and still use the 30%. These certainly are not sientific results. Just seat of the pants stuff. But nevertheless. I can feel the difference and so far I don't see any negatives to 30%. Well, except cost.
Thanks,
Barry