It Must be the Look...Performance is Lacking
On the RV series of aircraft, people are getting over 200 mph with engines in the 190 to 200 hp range (4 cylinders Lycomings). Some folks are "stuffing" their RVs with 6 cylinder Lycomings and getting 225 mph, but there could be some safety issues if not properly engineered for that up grade.
Many attempts to use auto engines (Honda) in lieu of aircraft engines have been met with less than "wild" success and, in numerous cases, out right unsafe installations.
The plane will look and sound cool...I bet.