Wondering which engine to power your Legal Eagle with? Half VW or Verner 3V or some other engine! Goes back to what your desired mission for the flying machine is.
1/2 VW is a great choice, with thousands of engines flying on eagles and all kinds of other aircraft. Parts are readily available and not that expensive and can be worked on by most mechanically inclined people. Horse power varies between 27 and 45 with weight in range where Legal Eagle is designed. My Scott Cassler 1/2VW has 450 hours on it and has taken me up to 11,000 feet above seal level starting at a density altitude above 8,000 foot. Fuel consumption of about 2.4 gallons per hour at cruise of 2800 rpm. Gets off ground with my fat ass in 150 feet on hard surface runway at 240 MSL. What more do you want. Huge base of users with all kinds of experiences and collectively a lot of engine run time.
Verner 3V has different radial appeal, more torque and lower RPM so larger diameter prop and more efficient. Fuel burn at cruise of 2050 ROM is 2.1 gallons per hour. Has electric start but it needs to be removed to stay part 103. Engine costs more, 2 of Scott Cassler 37 hp engines cost about same as one 3V. It does out climb and gets off ground a little faster than the 1/2VW. Engine mounts and long term effects on fuselages still in study mode and total number of 3V engines in operation is probably less than 50 at this time. They are a great engine, designed for aircraft in place of converted from automotive use.
Other choices, first question is to ask is how many of your favorite choices for other engine system do you see at Oshkosh each year and is there more there each year. If it is a great choice other people would’ve picking up on it and more would be seen in operation. If your flying goal is to tinker with the engine side of flying and experiment engine wise, have fun, just be aware there may not be much of a builder/user base to learn from/with.
For the Legal Eagle XL there is approximately 90 pounds available for firewall foward and to remain part 103. This varies by build and what builder has added, changed in building machine to firewall point. Examples of major weight items are wheels, tires, brakes and struts, round versus stream line. When i changed the 1/2 VW, 45 hp version with dual mikuni carbs to the Verner 3V i weighed everything very carefully and with the starter motor removed from Verner it came out, firewall and firewall forward 4 lbs lighter than the 1/2 VW. This included everything necessary to fly for both engines, i.e. throttle cables, mounting bolts, props, oil tanks, hoses etc.
In summation, the 1/2 VW is a great way to go and will do everything needed with the Legal Eagle.
My interest in the 3V is for a wood and fabric scale replica of a biplane from the early 1920s. To maintain an authentic historical look, the nose bowl should be shaped in a way that precludes use of a starter (and the starter ring). This will not be a Part 103 aircraft, so the decision does not relate to weight. How has your experience been hand-propping the 3V? Any special issues (apart from the safety issues that always apply when hand-propping)? Presumably, the long prop helps.
Thanks for your insight!