If you live in an area where the temps are high like I do, I would go the 1515 route. In my experience the smaller motors have a harder time keeping cool in hot weather. In Houston it is above 95 ambient 6-7 months out of the year.
I'm not looking for a ton of power, but I need enough to beat my buddy's e-maxx that has a velion. I am also looking for runtime. what #/y or d would be the best for 12 cell nimh/4S lipo.
So if I got a 1512 2D or something like that I should be able to beat it no problem. How long of run times am I looking at on 4S nue energy 5000mah lipo?
Judging by the results others have had, the 1512 2d is a great motor on 4s lipo- easily more power than a hvmaxx system, and geared correctly runs plenty cool, even in the erevo which is heavier than either new or old emaxx. That said, if your friend starts a game of one-up manship, you may quickly find yourself wanting the larger 1515 motor...