I see that the Generac and other V-Twin industrial engines are starting to show up on ultralight aircraft and powered paragliders. The great thing about these engines is the low cost, newer technology, and easy service/repair. They come with alternator, starter, and electronic ignition built in. On the other hand, the 1/2 VW can be built with a magneto so no battery or alternator is needed so the weight can be kept down to 85lbs or so. Also the 1/2VW should be built with high performance parts like Mahle pistons, Scat Crank and Rods, etc. Everything in life is a trade-off. The cost for these engines will be about the same until you start putting extras on the 1/2VW like starter, alternator, etc. These parts can be very pricey. A nice 37hp 1/2VW with a magneto is $3400 without extras at Hummel Engines. However, I will build and sell a 37hp 1/2 VW for $2900 including prophub, magneto, exhaust, intake, and carb ready to go. A stock 32hp Generac V-Twin is about $1700 without prop hub (including alternator and starter!:gig. Both the industrial V-Twins and the 1/2 VW are rated at 3600rpm. Since the industrial engine and the 1/2VW are so similar in performance, the direct drive prophub should work as well on the industrial engine as it does on the 1/2VW. Props will be limited to about 54in in both cases. It is relatively easy to design a belt reduction drive for the industrial engines so a longer prop can be used and more thrust will result. Now if I just had a low-cost redrive for the 1/2VW. What do ultralight builders think of these engines?