Size of the engine alone doesn't have much to do with speed in these cases. One would think that doubling the horsepower of an engine would give you much more speed, but it rarely gives you as much as you wish. Look at Hoot Gibson. Set records in a O-200 Cassutt racer I believe. That has less power than most of your newer trainers, but it outstrips every piston at MBT. It was designed to go fast and climb fast.