The K&B .48 ABC (Screamin' .48) engine is a great engine as long as you let it do what it's name implies......scream. I is not an engine that will lug a big prop, so prop it so it will turn at 15000 rpm in flight, that's where it makes it's power. It will last a long,long time if you run fuel with castor as part of it's oil package. Learn how to change out bearings when it needs it and it will be a long time servant.