It would be easier to answer specific questions. I have flown a 4.2 quite a bit and owned a 2.4 for awhile. I would rate them as an expensive, dated engine by todays standards but they are well made and will last a long time. Modern engines of the same displacement will have more power and torque I would rate them as being very comparable to a Brison. I hated the small diameter, replaceable prop stud!