I have a Q42 sitting in my shop now for maybe 10 years. A very good engine but it's always too heavy or too underpowered to use in what I'm building ( my choice I know ). As a point of comparison I have a Brison 2.4 that weighs 3.5 lbs. all dressed and will spin an 18-10 at 8000 rpms. the Q42 weighs 4.5 lbs. all dressed and will spin the same prop at 7000 rpms, a huge difference. Someday I'll find a plane to put it in.