By using the DA 100 you can accelerate straight up at half throttle. This keaps the prop from reaching an rpm wich would cause rip. With the smaller engine you need full throttle causing the prop to reach an rpm were it will rip. By the way I agree with y ou that the ZDZ is a great engine I had a 80 single it had unbelievable power. Due to a mid air I no longer own it. ™g